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WORLD HEALTH ORGANIZATION

ORGANISATION MONDIALE DE LA SANTE

VII. TEE HOUSE-FLY - BIOLOGY AMD CONTROL

3 . Keiding Danish Pest Infestation Laboratory

Lyngby, Denmark

The issue of this document does not constitute

formal publication. It should not be reviewed,

abstracted, quoted or translated without the

agreement of the World Health Organization.

Authors alone are responsible for views expressed

in signed articles.

Ce document ne constitue pas une publication,

II ne doit faire I'objet d'aucun compte rendu ou

rdsume ni d'aucune citation ou traduction sans

l'autorisation de I'Organisation mondiale de la

SantB. Les opinions exprimhes dans les articles

signds n'engagent que leurs auteurs.

CONTENTS

I Introduction ................................................................... I1 Taxonomy. nomenclature and geographical distribution ........................... I11 Life history. biology and ecology ..............................................

111.1 Life history ............................................................. 111.1.1 The eggs ......................................................... 111.1.2 The larv~ae ....................................................... 111.1.3 The pupae ........................................................ 111.1.4 The adult fly ....................................................

111.2 Breeding sources ......................................................... 111.2.1 Dung ............................................................. 111.2.2 Garbage and wastes from food processing .......................... 111.2.3 Organic manure other than dung ................................... 111.2.4 Sewage ........................................................... 111.2.5 Accumulations of plant material ..................................

111.3 Seasonal fluctuations and overwintering .................................. 111.4 Biology and behaviour of adult flies .....................................

111.4.1 Feeding .......................................................... 111.4.2 Distribution by day and by night ................................. 111.4.3 Dispersion .......................................................

IV Public health importance of house-flies ........................................ IV.l Potential of flies for transmission of disease ........................... 1V.2 Important diseases that may be transmitted by non-biting flies under

certain conditions ....................................................... IV.3 Fly nuisance .............................................................

V Fly control .................................................................... V.l Environmental sanitation and hygiene .....................................

V.l.l Elimination or reduction of fly breeding ......................... V.1.2 Elimination of sources that attract flies from other areas ....... V.1.3 Exclusion of flies from contact with materials containing

pathogenic germs ................................................. V.1.4 Protection of food. utensils and man from contact with flies

(non-chemical methods) ........................................... V.1.5 Education and public cooperation in environmental sanitation

programmes ....................................................... V.2 Insecticidal control .....................................................

V.2.1 Larvicides ....................................................... V.2.2 Residual treatment of resting-sites .............................. V.2.3 Impregnated strips. cords. etc ................................... V.2.4 Toxic baits ...................................................... V.2.5 Space treatments and direct spraying of fly aggregations ........a

V.2.6 Fumigation .......................................................

Page

.................................... V.3 House-fly resistance to insecticides ........................................ V.3.1 Development of resistance V.3.2 Occurrence of resistance in various insecticides ................. V.3.3 Nature of resistance ............................................. V.3.4 Cross-resistance and multiple resistance ......................... V.3.5 Stability of resistance .......................................... V.3.6 Preventing or reducing the development of resistance ............. V.3.7 Significance of resistance for fly control .......................

V.4 Biological and other means of control .................................... V.4.1 Biological control and regulation of house-fly populations ....... ............................ V.4.2 Sterility methods and genetic control V.4.3 Trapping .........................................................

V1 Fly survey methods ............................................................. VI.l Counting flies on selected areas or attractants ..........................

VI.l.l The fly grill count .............................................. VI.1.2 Counts of flies landing on baits ................................. ........................ VI.1.3 Counts or estimates on available surfaces

VI.2 Trapping flies ........................................................... VI.2.1 Baited traps ..................................................... VI.2.2 Sticky traps ..................................................... VI.2.3 Light traps ......................................................

VI.3 Catching flies ........................................................... VI.3.1 Sweeps of net .................................................... VI.3.2 Movable suction device ........................................... VI.3.3 The fly cone .....................................................

VI.4 Counting fly specks ...................................................... c I Glossary ....................................................................... V111 Selected references ............................................................ IX Evaluation .....................................................................

A . Questionnaire for self-evaluation ........................................... ...... B . Questionnaire for return to the Division of Vector Biology and Control

The common h o u s e - f l y , k u s c a d o m e s t i c a L., h a s f o l l ~ w e d man and been a n u i s a n c e t o people a l l o v e r t h e wor ld whereve r l i v e s t o c k a r e k e p t o r ga rbage* a c c u m u l a t e s ( F i g . l ) . Musea d o m e s t i c a d e s e r v e s i t s name a s i t i s by f a r t h e most common f l y i n and around h o u s e s 2 v i l l a g e s and i n u r b a n a r e a s w i t h i n s u f f i c i e n t s a n i t a t i o n . The h o u s e - f l y i s of p u b l i c hea l th i m p o r t a n c e , b e c a u s e i t may t r a n s m i t i n f e c t i o n s t o food and p e o p l e , and because i t i s a plague a d d i n g t o t h e d a i l y burden o f p e o p l e l i v i n g u n d e r poor s a n i t a r y c o n d i t i o n s , and Unacceptable where l i v i n g c o n d i t i o n s and h y g i e n e a r e a t a h i g h e r l e v e l .

F i g . 1. Musca d o m e s t i c a d o m e s t i c a L. f ema le (Denmark)

M. d o m e s t i c a i s a t y p i c a l s y n a n t h r o p i c * f l y ( s y n - a n t h r o p i c means t o g e t h e r w i t h E) a s , w i t h few e x c e p t i o n s , i t is d e p e n d e n t on human s e t t l e m e n t s and a c t i v i t i e s , i nc lud i -ng t h e keeping o f domes t i c a n i m a l s , i t b r e e d s i n human w a s t e and manure o f a n i m a l s , i t f e e d s on man's food and g a r b a g e , and u s e s human b u i l d i n g s f o r s h e l t e r . The re a r e many o t h e r s y n a n t h r o p i c f l i e s of p u b l i c h e a l t h i m p o r t a n c e , which w i l l n o t be d e a l t w i t h i n t h i s b r o c h u r e ; however, M. domest ica i s t h e most common and w i d e s p r e a d s p e c i e s * .

The a r e a o f o r i g i n of M. d o m e s t i c a is no t known, b u t i t s b i o l o g y and d i s t r i b u t i o n p o i n t t* a s u b t r o p i c a l o r t r o p i c a l a r e a i n t h e Old World, pe rhaps E a s t A f r i c a , and i t seems t o have f o l l o w e d man from t h i s e a r l i e s t development .

* The t e rms marked w i t h an a s t e r i s k a r e d e f i n e d i n S e c t i o n V 1 1 - G l o s s a r y .

WFI0/VBC/86.937 page 5

11. TAXONOMY*, NOMENCUTUTIE* AND GEOGRAPHICAL DISTRIBUTION

Classification of the Diptera* y f public health impurtance:

arde r Diptera Flies

suborders 3emat?cera1 Brachbcera2 Cyclo?rhapha3 I i I

Families ~ulicidae ~sychddidae ~imul/idae ~eratodogonidae Tabanidae Huscidae Glossinidae Calliphoridae ~es?ridae 1

Hosquitos includes BlackfLtes Biting midges Horseflies House- Tsetse flies Blowflies, etc. Warble flies Sandf lies flies, etc.

1) Antennae* with many segments ( > 6 ) 2 ) Mainly large flies, antennae wirh three segments, the last being the largest 3) Antennae with three segments. The last bears a bristle called the arista*.

M. domestica belongs to the Class Insecta. In the Order Diptera* along with the majority of two-winged insects, they are members of the suborder Cyclorrhapha, as shown on the above chart illustrating the classification of Diptera of public health importance.

The genus Musca belongs to the family Muscidae which also contains other synanthropic flies, e.g. Stomoxys, Muscina and Fannia (West, 1951). The genus Musca consists of about 26 species most of which are "wild" and of no public health importance. The Musca species are generally medium-sized flies, with non-metallic black-and-grey striped thorax and a sharp angle in the fourth longitudinal vein of the wing.

The taxonomics of the domestic (and endophilic*) forms of Musca are still unclarified. .It is generally agreed that they all belong to one species, M. domestica, but for many years four different subspecies were distinguished: M. d. domestica Linnaeus found in temperate zones all over the world, extending into subarctic and subtropical areas, M. d. vicina Macqvart, found in subtropical and tropical zones in many regions, e.g. in the Mediterranean, Asia, Africa, South and Central America, Pacific and Australia, M. d. nebulo Fabricius, found only in tropical Asia, and M. d. curviforceps Saccil h Rivosecchi restricted to Africa, where it is the common house-fly south of the Sahara (Sacca, 1964) (Fig. Zb).

However, recent investigations suggest that all Musca domestica outside Africa should be regarded as one subspecies M. domestica domestica, including the three previous subspecies, domestica, vicina and nebulo. These were mainly distinguished by the size of the compound eyes (measured as the frons ratio, see Figs. 2, 3) in the males and the pigmentation of the

- abdomen. However, these characters show overlapping and vary, not only from north to south, but also according to climatic conditions within an area, e.g. due to altitude. In future investigations it will still be of interest to characterize house-fly populations morphologically in various geographical and climatic localities by recording f rons ratio in samples of males, but the former subspecific names should not be used.

The ecology and habits of house-fly populations (M. d. domestica) may vary in different parts of the world, adapted to local climate and other conditions (see section IV), but it is ulcertain which, if any, of these biological differences are connected with morphological characters.

domest~cd - nebulo curviforceps calteva

Fig . 2a. The range and d e t e r m i n a t i o n of f r o n s r a t i o F/H (wid th of f r o n s d i v i d e d by width o head) i n male h o u s e f l i e s (From Saccb, 1967) .

F ig . 2b. Some d i f f e r e n t i a l c h a r a c t e r s between male M. d . domes t i ca , M. d. c u r v i f o r c e p s and M.calleva. Below: heads , middle , d o r s o - c e n t r a l b r i s t l e s ; above: shape o pa ra lobus of t h e t e r m i a l i a (From Saccb, 1967).

Fig. 3. Pigmentat ion oE the d o r s a l abdomina and average f r o n s r a t i o i n s i x s t r a i n s of M. d. domest ica bred a t v a r i o u s t empera tu res (From Sacch, 1967) . -

I n A f r i c a two i d e n t i f i a b l e s u b s p e c i e s of M. d o m e s t i c a o c c u r : t h e d o m e s t i c e n d o p h i l i c M . d. c u r v i f o r c e p s , ment ioned a b o v e , and t h e e x o p h t l i c * M. d . c a l l e v a Walker ( = t.1. c u t h b e r t s o n i P a t t o n ) . These two common A f r i c a n s u b s p e c i e s r e g u l a r l y o c c u r i n t h e same l o c a l i t y , b r e e d i n g i n g a r b a g e i n h e a p s o f manure, b u t M. d . c a l l e v a d o e s no t a c t i v e l y e n t e r houses and i s p r o b a b l y o f l i t t l e p u b l i c h e a l t h i m p o r t a n c e . The two s u b s p e c i e s a r e i n t e r f e r t i l e * , b u t i n t e r b r e e d i n g i s r e s t r i c t e d due t o t h e d i f f e r e n c e i n h a b i t a t s e l e c t i o n .

Musca s o r b e n s Wiedemann is a d i s t i n c t s p e c i e s w i t h e x o p h i l i c h a b i t s i n most a r e a s , y e t i t i s of c o n s i d e r a b l e p u b l i c h e a l t h i n t e r e s t , because i t b r e e d s i n exc remen t o f man and d o m e s t i c a n i m a l s and l s s t r o n g l y a t t r a c t e d t o m o i s t human s k i n , e y e s , wounds, e t c . It is common i n A f r i c a , s u b t r o p i c a l and t r o p i c a l A s i a and i n t h e P a c i f i c . F u r t h e r , i t o c c u r s i n t h e ex t r eme s o u t h o f Europe and i n Ifawaii . M. v e t u s t i s s i m a Walker , t h e A u s t r a l i a n "bush - f ly" , i s c l o s e l y r e l a t e d t o M. s o r b e n s and h a s s i m i l a r h a b i t s . M. s o r b e n s and M. v e t u s t i s s i m a a r e e a s i l y d i s t i n g u i s h e d from t h e M. d o m e s t i c a fo rms by h a v i n g o n l y two broad d a r k s t r i p e s on t h e d o r s a l thorax*, whe reas t h e M. d o m e s t i c a fo rms have f o u r s t r i p e s ( F i g . 4 ) .

F i g . 4 Musca s o r b e n s (V ied . ) f e m a l e 5.5 mm (From c o l o u r p l a t e i n Greenbe rg , 1971) .

111, LIFE HISTORY, BIOLOGY AM) ECOLOGY

1 . L i f e h i s t o r y ( F i g . 5 )

111-1 .1 The e g g s

The banana-shaped e g g s a r e 1-1.2 mm l o n g , o p a l - w h i t e t o c ream c o l o u r e d . C l u s t e r s of e g g s a r c d e p o s i t e d by t h e f ema le f l y i n d e c a y i n g , f e r m e n t i n g o r p u t r e f y i n g o r g a n i c m a t t e r p rov ided i r !S m o i s t , but n o t l i q u i d . The e g g s r e q u i r e a h i g h h u m i d i t y , below 90% r e l a t i v e humid i ty* (RH) t h e m o r t a l i t y i s h igh . The t ime f o r development from o v i p o s i t i o n t o h a t c h i n g depends on t h e t e m p e r a t u r e ( T a b l e l ) , from a minimuin %L: s i x t o e i g h t h o u r s a t 3S°C. No development t a k e s

below 130C. The p e r c e n t a g e o f e g g s h a t c h i n g i s h i g h between l5OC and 400C, b u t below S " ~ a i d above 42% a l l e g g s d i e b e f o r e h a t c h i n g .

F i g . 5. The l i f e c y c l e o f t h e h o u s e f l y ( 7 X m a g n i f i c a t i o n ) a . Female b. Egg b a t c h from one o v i p o s i t i o n of one female . c. F u l l y grown t h i r d i n s t a r l a r v a , d o r s a l view above, s i d e view below. Head t o t h e l e f t . Note mout hooks i n f o r e end and s p i r a c l e s i n h ind end. d. Pupae. L e f t t h e puparium, th ba r re l - shaped hardened s k i n of t h i r d l a r v a l i n s t a r , r i g h t t h e pupa t a k e n o u t from th puparium.

TABLE l. BIONOMICS* OF THE HOUSE-FLY

Le tha l development temperature

above

M : Matu ra t ion of

( p r e o v i p o s i -

T o t a l l i f e c y c l e E+L+P+M ( days )

WHO/VBC/86.937 page 9

111-1 .2 The l a r v a e

As i n most o t h e r f l i e s t h e r e a r e t h r e e l a r v a l i n s t d r s ( I , 11, and 1 1 1 ) s e p a r a t e d by mou l t s . I n s t a r I grows from l t o 3 mm, i n s t a r 11 from 3 t o 5 mm and i n s t a r 111 from 5 t o 12- l 3 mm. The l a r v a h a s a s l e n d e r c y l i n d r i c a l body w i t h a c o n i c a l t a p e r i n g a n t e r i o r ("head") a n d a rounde r p o s t e r i o r , w i t h no appendages ( F i g . 5 ) . I n s t a r s I , I1 and t h e f i r s t p d r t of 111 a r e t r d r i s l u c e n t , bu t t owards p u p a t i o n t h e l a r v a e become w h i t e o r y e l l o w i s h . It i s ma in ly t h e s e l a t e t h i r d - i n s t a r maggots , t h e s o - c a l l e d p repupae , t h a t a r e seen when a f l y b r e e d i n g s i t e i s i n v e s t i g a t e d . The l a r v a e have one s t r o n g and one s m a l l i n t e r i o r mouth hook used f o r f e e d i n g and locomot ion ; t h e two s c l e r o t i z e d * p l a t e s i n t h e p o s t e r i o r end , l o o k i n g l i k e a p a i r of b l a c k e y e s when viewed w i t h a hand- l ens ( F i g . 5 c ) , a r e s p i r a c l e s * w i t h s l i t s f o r t h e f i n e a i r - t u b e s , t h e t r a c h e a , p r o v i d i n g t h e body w i t h oxygen.

The l a r v a e i n i n s t a r s I , I1 and t h e f i r s t p a r t o f I11 a r e i n t h e f e e d i n g s t a g e s , and i n n a t u r a l media most o f t h e f e e d i n g i s on b a c t e r i a o r y e a s t s and t h e i r d e c o m p o s i t i o n p r o d u c t s , which p r o v i d e t h e n e c e s s a r y p r o t e i n (amino a c i d s ) , v i t a m i n s ( o f t h e B g r o u p ) and s t e r o l s . The f e e d i n g s t a g e s a r e a t t r a c t e d t o o d o u r s connec t ed w i t h b r e e d i n g media; t h e y p r e f e r a t e m p e r a t u r e of 3soC, r e q u i r e a h i g h h u m i d i t y ( i n s t a r I above 97% RH) and s t r o n g l y a v o i d l i g h t . They u s u a l l y o c c u r i n a g g r e g a t i o n s .

When t h e t h i r d - i n s t a r l a r v a e s t o p f e e d i n g and become p repupae , t h e i r r e a c t i o n s c h a n g e , e x c e p t t h a t t h e y s t i l l a v o i d l i g h t ; t h e y become i n d i f f e r e n t t o o d o u r s , and t h e y p r e f e r a l o w e r t e m p e r a t u r e , less t h a n 15-20°C, and a l ower humid i ty . A s t h e y a r e v e r y a c t i v e t h e r e s u l t i s t h a t t h e y m i g r a t e t o c o o l e r and d r i e r p l a c e s , e .g . s u r f a c e o r s i d e s o f heaps o f dung o r g a r b a g e , o r i n t o t h e s u r r o u n d i n g s o i l , where t h e p u p a t i o n t a k e s p l a c e , o f t e n i n a g g r e g a t i o n s o f hundreds o r t housands .

The time r e q u i r e d f o r t h e deve lopmen t o f t h e l a r v a e from h a t c h i n g o f t h e egg t o p u p a t i o n depends on n u t r i t i o n , m o i s t u r e and t e m p e r a t u r e ( T a b l e l ) , w i t h a minimum o f 3-3.5 d a y s unde r t h e most f a v o u r a b l e c o n d i t i o n s , i .e . 350C ( F i g . 6) . La rvae and pupae d o riot t o l e r a t e t e m p e r a t u r e s above 450C f o r l o n g p e r i o d s , which means t h a t i n a c c u m u l a t i o n s o f dung, g a r b a g e o r o t h e r f e r m e n t i n g o r r o t t i n g b r e e d i n g media , i t is o f t e n o n l y a na r row o u t e r zone , e .g. 10- 1 5 cm, where t h e maggots and pupae c a n d e v e l o p .

5 . Diagram showing d u r a t i o n o f i ieveiopment of e g g s + l a r v a e and e g g s + l a r v a e + p u p a r i a i n r e l a t i o n t o t e m p e r a t u r e .

WHOIVBC186.937 page l 0

When t h e l a r k 3 i s re , idy f o r p u p a t r o n , i t + s k i n c o n t r a c t s and i t f o r m s a b a r r e l - s h pnpar ium.* T h i s i s s o f t .ind w h i t e o r y e l l o w f o r t h e f i r s t o n e t o two h o u r s , a n d t h e n g r a d u c h a i ~ g e s t l l r u ~ t g t i l i g h t brown t o d a r k brown o r a l m o s t b l a c k w h i l e t h e c u t i c l e h a r d e n s . p r o c e s s u s u a l l y t l k e s p l a c e w i t h i n t h e f i r s t 24 h o u r s . I n s i d e t h e pupar ium t h e r e i s a h i s h o r t f o u r t h l a r v d l i n s t a r , b e f o r e t h e t r u e pupa i s f o r m e d ,

The d u r a t i o n of t h e p u p a r i u m s t a g e u n t i l t h e f l y e m e r g e s d e p e n d s on h u m i d i t y p a r t i c u l a r l y on t e m p e r a t u r e ( T a b l e l ) . I t is r o u g h l y o f t h e same l e n g t h a s t h e l a d e v e l o p m e n t , w i t h a mii~imum o f t h r e e t o f o u r d a y s a t 35-40°C a n d 90X RH. The pupae tale l o w e r i i u m i d i t i e s thdn t h e l a r v a e , b u t b e l o w 75% RH some d i e and be low 40% f e w s u r v i v e . l e t h a l t e m p e r a t u r e i s a b o u t 45°C a s i n t h e l a r v a l s t a g e , a n d b e l o w lZ°C t h e d e v e l o p m e n t s t i The a b i l i t y o f p u p a e a n d l a r v a e t o t o l e r a t e l o w e r t e m p e r a t u r e s i s d i s c u s s e d u n d e r o v e r w i n t e ( s e c t i o n l I I . 3 ) .

111 .1 .4 The a d u l t f l y

( a ) The e m e r g e n c e f r o m t h e p u p a r i u m . When t h e a d u l t f l y h a s b e e n f o r m e d i n s i d e p u p a r i u m , i t b r e a k s t h e f o r e e n d o f t h e p u p a r i u m by i n f l a t i n g t b e f r o n t a l s a c * , p u s h i n g , two f l a p s , a n d e m e r g e s q u i c k l y . The n e w l y emerged f l y i s s o f t , p a l e g r e y and w i n g l e s s . u s i n g t h e f r o n t a l s a c , i t i s a b l e t o "pump" i t s way up t h r o u g h t h i c k l a y e r s o f l o o s e s o i : o t h e r m a t e r i a l t h a t is n o t t o o s o l i d .

When i n t h e o p e n i t h a s a n a c t i v e w i n g l e s s p h a s e l a s t i n g 1 5 min o r more d e p e n d i n g t e m p e r a t u r e a n d o t h e r c o n d i t i o n s , u n t i l i t f i n d s a s u i t a b l e p l a c e t o r e s t , w h i l e t h e W

s t r e t c h and t h e c u t i c l e h a r d e n s a n d becomes d a r k . T h i s i m m o b i l e p h a s e l a s t s 0.5 t o 1 . 5 t m o r e , and i t t a k e s o n e t o s e v e r a l h o u r s b e f o r e t h e f l y c a n s t a r t t o u s e i t s wings . l o c a t i o n o f t h e r e s t i n g p h a s e i s i m p o r t a n t f o r t h e c o n t r o l o f f l i e s . The a c t i v e newly emel w i n g l e s s f l i e s h a v e w e l l - d e f i n e d r e a c t i o n s t o g r a v i t y and l i g h t , w h i c h l e a d them upwards m a i n l y t o w a r d s d a r k p l a c e s , w h e r e t h e y p r e f e r t o rest u p s i d e down, i f p o s s i b l e . The yc f l i e s s t a r t f e e d i n g when t h e y h a v e become a c t i v e a f t e r t h e w i n g - s t r e t c h i n g , f r o m two t o 2 a f t e r e m e r g e n c e a t 27%.

( b ) M a t i n g . M a l e s a r e a b l e t o c o p u l a t e t h e d a y a f t e r e m e r g e n c e (minimum 18 h ) -- f e m a l e s a t a n a g e o f 3 0 h a t f a v o u r a b l e t e m p e r a t u r e s . V i s u a l a t t r a c t i o n s e e m s mos t import f o r t h e m a t i n g , b u t o l f a c t o r y * s t i m u l i , i n c l u d i n g a s e x pheromone*, are a l s o i n v o l v e d (Cols & S h o r e y , 1 9 7 7 ) . A pheromone , m u s c a l u r e , i s p r o d u c e d by t h e f e m a l e ( C a r l s o n & L e i b o l d , 191 I t a t t r a c t s m a l e s a n d , t o a l e s s e r d e g r e e , a l s o f e m a l e s . R e c e n t l y a pheromone p r o d u c e d by m a l e s h a s b e e n d i s c o v e r e d ( S c h l e i n & G a l u n , 1 9 8 4 ) . I t i n d u c e s a g g r e g a t i o n a n d r e c e p t i v i t y v i r g i n f e m a l e s , b u t h a s no e f f e c t on m a l e s o r m a t e d f e m a l e s .

Most n o r m a l l y mated h o u s e - f l y f e m a l e s a r e monogamous a n d [ lone w i l l mate more t h a n a t i m e s . The l o s s o f s e x u a l r e c e p t i v i t y i s c a u s e d by c o m p o n e n t s o f t h e s e m i n a l f l u i d a t f i r s t e f f e c t i v e sating, a n d t h i s s u b s t a n c e a l s o s t i m u l a t e s c t v i p o s i t i o n . The s p e r m i s s t( i n t h e f e m a l e s p e r m a t h e c a e * dnd c a n f e r t i l i z e e g g s f o r a p e r i o d of up t o t h r e e weeks o r morc

( c ) O v i p q s i t i o n . The a g e a t w h i e h t h e f e m a l c i s a b l e t o l a y t h e f i r s t b a t c h o f c v

d e p e n d s t e m p e r a t c l r e ( T a b l e L ) arid t i i i s j>rt2_ioviposition* p e r i i i d v a r i e s f r o m 1 . 8 d a y s a t t o aho i i t n i n e d a y s a t 13°C. A s a rt1l.e : , v i p o s i t i o n d o e s n o t t a k e p l a c e a t a i r t e m p e r a t r h e l o w 15°C. G r a v i d f e m ~ l i > s :Ire p r i m a r i l y a t t r a c t e d t o t h e h r e e d i n g med iim by i t s s m e l l , which c a r b o n d i o x i d e , arnrnor~isi, and v i i r i o i i s o t h e r i > d o u r s o f diing and r o t t i n g o r fe rment m a t e r i a l s a r e i n v o l v e d . ( D e t a i l ? 3b011t b r e e d i n g s o u r c e s atid sites a r e g i v e n i n S e c t i o n s 11 and V . l . 1 ) . The e g g s a r e L-lid b c i l e a t h t h e s u r f a c e , i n c r e v i c e s , e t c . , w h e r e t h e y a r e p r o t e c a g a i n s t d i i s i c c a t i o r l .

The n u ~ b e r {if egg.; jlcr v v i p o s i t i v n i z 71r~rmi;i1 l y abotlt 12'3, If i i n d i c ; t u r b e d , t h e fen u s i l a l i y i d y > i l ~ r t n i i i O I I ~ c i r ~ s i e r aiia titLe11 i r i l e r a l teinaieb i a v e g g s i i i Lrle same b p b t . l a b o r a t o r y c o l o n i e s a f e m l e h o u s e - f l y may p r o d u c e L 0 h a t c h e s o r more , b u t u n d e r natL f a v o u r a b l e c o n d i t i o n s i t may be o n l y o n e :)r two, a s t h e l n r l g e v i t y o f t h e f l i e s i s u s u a l l y n l e s s t h a n i n t h e l ~ b o r a t o r y .

WHO/VBC/86.937 page 11

( d ) Length o f l i f e . Expe r imen t s on Dan i sh f a rms have shown t h a t 50% of t h e f l i e s d i e d u r i n g t h e f i r s t 3-6 d a y s and v e r y f ew r e a c h a n a g e of 8-10 d a y s , e v e n i f no c h e m i c a l c o n t r o l i s a p p l i e d , whe reas i n t h e l a b o r a t o r y t h e mean l i f e s p a n o f a d u l t f l i e s was found t o be 1 7 d a y s f o r ma le s and 29 days f o r f e m a l e s ( a t 25% and 45% R H ) . Most p e o p l e conce rned w i t h house- f l y c o n t r o l have assumed t h a t t h e l o n g e v i t y found i n t h e l a b o r a t o r y (mean l i f e s p a n of 3-4 weeks o r more) a l s o a p p l i e d t o t h e f i e l d . The f i n d i n g of a much s h o r t e r l i f e - e x p e c t a n c y i n t h e f i e l d , which h a s been con f i rmed i n l a t e r i n v e s t i g a t i o n s i n Denmark and i n Eng land , i s o f impor t ance f o r c o n s i d e r a t i o n s o f t h e e f f e c t and s t r a t e g y o f h o u s e - f l y c o n t r o l . I t means t h a t a h i g h p r o p o r t i o n of f ema le f l i e s d i e b e f o r e t h e y have had a chance t o l a y e g g s and v e r y few f l i e s w i l l l a y two o r t h r e e b a t c h e s o f e g g s unde r t h e c o n d i t i o n s o n t h e Dan i sh f a rms . The c a u s e s o f t h e s h o r t e r l i f e a r e n o t known, b u t i n Denmark i n f e c t i o n w i t h t h e f l y f u n g u s Entomophthora muscae seems t o p l a y a n i m p o r t a n t r o l e , dependen t on t h e t y p e o f a n i m a l h o u s e s ( t e m p e r a t u r e , h u m i d i t y ) and t h e s e a s o n . A r e c e n t s t u d y o f h o u s e - f l i e s on a J a p a n e s e g a r b a g e dump showed a d a i l y s u r v i v a l r a t e of 0 .60 t o 0 .87 ( I m a i , 1984) .

( e ) R e p r o d u c t i v e p o t e n t i a l * . The number o f g e n e r a t i o n s p e r y e a r may v a r y from a b o u t 30 u n d e r t r o p i c a l c o n d i t i o n s t o a b o u t l 0 o r l e s s i n t e m p e r a t e c l i m a t e s . Even w i t h a c o n s e r v a t i v e a s s u m p t i o n of 100-200 o f f s p r i n g p e r f e m a l e , t h e t h e o r e t i c a l c a p a c i t y o f i n c r e a s e i s enormous , and when new f a v o u r a b l e b r e e d i n g o p p o r t u n i t i e s a r e c r e a t e d sudden o u t b u r s t s o f f l y i n f e s t a t i o n may o c c u r . Obv ious ly , a l i m i t f o r t h e i n c r e a s e i s t h e amount o f b r e e d i n g medium a v a i l a b l e , t hough 5000-10 000 h e a l t h y f l i e s may be produced p e r k i l o g r a m o r l i t r e o f f a v o u r a b l e medium. However, even i f t h e r e i s p l e n t y o f unused food f o r l a r v a e and a d u l t s , e .g. a f t e r c h e m i c a l o r c l i m a t i c s u p p r e s s i o n o f t h e f l i e s , o r a t t h e s t a r t o f t h e f l y s e a s o n , t h e r a t e of i n c r e a s e i n a f i e l d p o p u l a t i o n is s t r o n g l y r educed by n a t u r a l m o r t a l i t y f a c t o r s . Thus on f o u r s u b t r o p i c a l f a r m s i n F l o r i d a , U n i t e d S t a t e s o f Amer ica , t h e maximum i n c r e a s e p e r two weeks a t t h e s t a r t o f t h e f l y s e a s o n was found t o be 6-8 times, whereas on 25 t e m p e r a t e f a rms i n Denmark i t was 10-22 times on h a l f o f t h e f a rms and 3-9 times on t h e r e s t . I f t h e c o n d i t i o n s f o r b r e e d i n g are f a i r l y c o n s t a n t , a s t a b l e p o p u l a t i o n may b e e s t a b l i s h e d , h i g h o r low a c c o r d i n g t o t h e m o r t a l i t y f a c t o r s p r e s e n t - c l i m a t i c , b i o l o g i c a l and c h e m i c a l . T h i s was d e m o n s t r a t e d d u r i n g a two-year f i e l d s t u d y i n Grand Turks I s l a n d i n t h e C a r i b b e a n , where t h e p o t e n t i a l r a t e s o f i n c r e a s e o f h o u s e - f l i e s were low d e s p i t e t h e i r h i g h b i o t i c p o t e n t i a l (Weidhaas & LaBrecque , 1970) .

111.2. Breed ing s o u r c e s

House - f l i e s c a n b r e e d i n a v a r i e t y o f d e c a y i n g , f e r m e n t i n g o r r o t t i n g o r g a n i c m a t t e r , o f b o t h a n i m a l and v e g e t a b l e o r i g i n ( S c h o o f , e t a l . , 1954) . They r a r e l y i n f e s t meat o r c a r r i o n , which i s t h e p r o v i n c e o f b l o w - f l i e s and f l e s h - f l i e s .

111.2 .1 Dung

Accumula t ions o f dung c o n s t i t u t e a most i m p o r t a n t and p r o b a b l y t h e o r i g i n a l s o u r c e o f h o u s e - f l y b r e e d i n g ( H a i n e s , 1953 , 1955) . Whereas i s o l a t e d d r o p p i n g s a r e o f l i t t l e i m p o r t a n c e f o r Musca d o m e s t i c a , t h e y a r e t h e p r imary s o u r c e o f M. s o r b e n s (Mau, 1 9 7 8 ) and M. v e t u s t i s s i m a . H o u s e - f l i e s may b r e e d i n a c c u m u l a t i o n s of dung of most d o m e s t i c a n i m a l s and b i r d s , p rov ided i t h a s t h e r i g h t m o i s t u r e ( n o t t o o w e t ) and t e x t u r e ( n o t t o o s o l i d ) , b u t t h e u t i l i z a t i o n and s u i t a b i l i t y o f dung f o r f l y b r e e d i n g v a r y c o n s i d e r a b l y a c c o r d i n g t o wh ich a n i m a l produced i t , t h e f e e d o f t h e a n i m a l s , t h e d e p o s i t i o n , s t a c k i n g and mix ing o f t h e dung w i t h bedd ing m a t e r i a l , t h e c l i m a t e , e t c . B e s i d e s , h o u s e - f l i e s seem t o have d i f f e r e n t p r e f e r e n c e s f o r a d a p t a t i o n s t o dung i n v a r i o u s g e o g r a p h i c a l a r e a s . The most i m p o r t a n t example i s cow dung, which i s a v e r y i m p o r t a n t s o u r c e o f f l y b r e e d i n g i n many p a r t s o f t h e w o r l d , b u t i n n o r t h and wes t Europe dung o f a d u l t c a t t l e u s u a l l y d o e s n o t b r e e d h o u s e - f l i e s , and cow dung h a s been recommended a s a c o v e r on t o p o f p i g manure t o p r e v e n t f l y b r e e d i n g . However, dung o f c a l v e s , a s l o n g a s t h e y a r e f e d m i l k , i s a n e x c e l l e n t b r e e d i n g s o u r c e eve rywhere , and i n n c r t h Europe c a l f pens may be t h e most i m p o r t a n t b r e e d i n g s i t e s f o r h o u s e - f l i e s on f a rms .

I n many r e g i o n s human exc remen t i s a t t r a c t i v e t o h o u s e - f l i e s and open l a t r i n e s a r e i m p o r t a n t b r e e d i n g s o u r c e s , b u t i n some a r e a s (e .g . n o r t h e r n Europe ) human excrement d o e s n o t a t t r a c t house-f l i e s .

WHO/VBC/86.937 page l 2

Where a v a i l a b l e , p i g dung seems t o be t h e p r e f e r r e d and most f l y - p r o d u c t i v e t y p e o f d (Asche r , 1 9 5 8 ) ; h o r s e dung i s a l s o a n e x c e l l e n t f l y b r e e d i n g s o u r c e , b u t o n l y f o r a s h o r t t due t o i t s r a p i d compos t ing p r o c e s s . F l y b r e e d i n g i n a c c u m u l a t i o n s o f p o u l t r y exc remen t become a g r e a t problem i n modern egg and c h i c k e n i n d u s t r y , i n v o l v i n g b o t h M. d o m e s t i c a and lesser h o u s e - f l i e s ( F a n n i a s p e c i e s ) . O t h e r k i n d s of dung t h a c may p l a y a r o l e f o r b r e e d i n g l o c a l l y i n c l u d e donkey, r a b b i t , g o a t , s h e e p , b u f f a l o , and camel . Dung is o s u i t a b l e f o r f l y b r e e d i n g i n t h e f i r s t few d a y s t o a week a f t e r d e p o s i t e d . A s a r u l e hou f l i e s do n o t b r e e d much i n composted dung.

111.2.2 Garbage and w a s t e s from food p r o c e s s i z

Garbage i n c l u d e s w a s t e s from t h e p r e p a r a t i o n , c o o k i n g and s e r v i n g of f o o d , and mar w a s t e s from t h e h a n d l i n g , s t o r a g e and s a l e o f food. I t is a v e r y i m p o r t a n t s o u r c e o f b r e e d i n g , and i n u r b a n a r e a s i t i s t h e predominant s o u r c e f o r b o t h h o u s e - f l i e s and o t s y n a n t h r o p i c f l i e s , p a r t i c u l a r l y b l o w - f l i e s , r a n g i n g from i n d i v i d u a l househo ld g a r b a g e t h r o r e f u s e a t food s h o p s and m a r k e t s t o g a r b a g e dumps ( S c h o o f , e t a l . , 1954) . T h i s i s f u r t d i s c u s s e d i n s e c t i o n V . 1 . F l y b r e e d i n g is n o t c o n f i n e d t c a c c u m u l a t i o n s of g a r b a g e , b u t a l s o t a k e p l a c e i n s o i l mixed w i t h g a r b a g e o r impregna ted w i t h s eepage .

Var ious w a s t e s f rom food p r o c e s s i n g and i n d u s t r y may a l s o be a s o u r c e o f s e r i o u s house- b r e e d i n g , e .g. i n connex ion w i t h c a n n i n g o f v e g e t a b l e s and f r u i t , b r e w e r i e s and d i s t i l l e r i s u g a r p l a n t s , e tc . ( I m a i , 1984) .

P r o c e s s i n g o f f i s h and mea t , a s w e l l a s t r e a t m e n t o f v e g e t a b l e s , o f t e n g i v e rise s e r i o u s f l y problems. Al though b l o w - f l i e s a r e u s u a l l y dominan t where a n i m a l p r o t e i n i s s o u r c e , h o u s e f l i e s somet imes b r e e d i n g r e a t numbers; f o r i n s t a n c e i n s o i l h e a v i l y contamina w i t h b lood , f i s h o r s l a u g h t e r o f f a l .

I n a g r i c u l t u r e , w a s t e from growing f r u i t o r v e g e t a b l e s , e .g . d i s c a r d e d t o m a t o e s o r me10 may be a b r e e d i n g s o u r c e o f many h o u s e - f l i e s .

111.2.3 Organ ic manure o t h e r t h a n dung

I n some a r e a s , where f i e l d s a r e h e a v i l y manured w i t h o r g a n i c m a t t e r , h o u s e - f l i e s may brg i n g r e a t numbers i n t h e f i e l d s , p a r t i c u l a r l y i f t h e manure i s a p p l i e d i n lumps. B e s i d e s du such manure may i n c l u d e exc remen t , g a r b a g e , f i sh -mea l , b lood- and bone-meal, o i l - s e e d cakg prawn d u s t , e t c .

111.2.4 Sewage

Under s u i t a b l e c o n d i t i o n s h o u s e - f l i e s may b r e e d i n sewage s l u d g e and s o l i d o r g a n i c wa: i n open sewage d r a i n s , c e s s p o o l s , s e e p a g e p i t s , e t c . , o r i n sewage beds . Moreover, f l i e s I

b r e e d i n s o i l w e t t e d by househo ld d i s h w a t e r , where a sewage s y s t e m i s l a c k i n g .

111.2.5 Accumula t ions o f p l a n t m a t e r i a l

P i l e s of d e c a y i n g g r a s s c l i p p i n g s o r g a r d e n compost h e a p s have been found a s impor t . s o u r c e s of h o u s e - f l i e s i n some u r b a n aqd s u b u r b a n a r e a s ( S i l v e r l y 5 Schoof , 19551, and i n r u a r e a s f l i e s may b r e e d i n s i l a g e (Meyer & P e t e r s e n , 1 9 8 3 ) and i n heaps o f o t h e r r o t t v e g e t a b l e m a t t e r . Heaps of s e a g r a s s o r seaweed s n b e a c h e s may b reed Stomoxys, t h e b i t s t a b l e f l y and c e r t a i n o t h e r f l i e s , b u t r a r e l y h o u s e - f l i e s .

111.3. S e a s o n a l f l u c t u a t i o n s and o v e r w i n t e r i n g

I f no c o n t r o l measu re s a r e u s e d , t h e f l y d e n q i t y i n a g i v e n locality w i l l g ene ra f l u c t u a t e w i t h t h e c o n d t t i o n s f o r b r e e d i n g and r e p r o d u c t i o n ; i n p a r t i c u l a r t h e a i r t empera t ' i n f l u e n c e s t h e r a t e o f m a t i n g , t h e p r e o v i p o s i t i o n p e r i o d , o v i p o s i t i o n and f e e d i n g o f adul l The temperalure of ~ l l e hreei i i t lg ueJ i i . -a .11t,i, a f , - t ~ t o r , L r * t ; , F L ~ i l t ir~g heaps of dui ga rbage , e t c . , a n o p t i m a l t e m p e r a t u r e w i l l o f t e n be r e a c h e d , even i f t h e a i r t e m p e r a t u r e low. I n such s i t e s l e t h a l h i g h t e m p e r a t t l r e s i n h o t p e r i o d s may l i m i t b r e e d i n g . I n t r o p i c

W~O/VBc/86.937 page l 3

and s u b t r o p i c a l a r e a s d e s i c c a t i o n o f b r e e d i n g media i n h o t and d r y p e r i o d s may a l s o r e s t r i c t f l y b r e e d i n g . I n s u b t r o p i c a l a r e a s ( e .g . Egyp t ) w i t h a v e r y h o t and d r y summer and c o o l w i n t e r , t h e r e w i l l o f t e n be a s p r i n g and autumn maximum a t mehn t e m p e r a t u r e s of 20-250C, a summer d e p r e s s i o n and low d e n s i t y i n t h e w i n t e r (Madwar & Zahar , 19531.

Even i n some a r e a s w i t h a t e m p e r a t e c l i m a t e i n v o l v i n g h o t summers, t h e summer d e p r e s s i o n may o c c u r . However, i n most t e m p e r a t e and s u b t r o p i c a l r e g i o n s t h e u s u a l p a t t e r n i s t h a t o f a w i n t e r p e r i o d w i t h few t o v e r y few f l i e s , a g r a d u a l o r sudden i n c r e a s e i n s p r i n g , a summer f l y s e a s o n o f t h r e e t o e i g h t months and a d e c l i n e i n t h e autumn. i n a r e a s w i t h a c o a s t a l t e m p e r a t e c l i m a t e ( e . g . n o r t h w e s t E u r o p e ) t i le f l r i n c i d e n c e i s c i , r r r l & t e d w i t h t h e h o u r s tf s u n s h i n e and i s d e p r e s s e d i n wet p e r i o d s ,

O v e r w i n t e r i n g . The q u e s t i o n of how house - f ly p o p u l a t i o n s o v e r w i n t e r , e s p e c i a l l y i n p l a c e s w i t h a c o l d w i n t e r , i s s t i l l b e i n g d i s c u s s e d . M. d o m e s t i c a h a s n:, : rue d i a p a u s e , a n d must i n v e s t i g a t o r s a g r e e t h a t , whenever p o s s i b l e , t h e house - f ly w i i l o v e r w i n t e r by s l o w b r e e d i n g i n b u i l d i n g s , p a r t i c u l a r l y cow s h e d s and t r t he r s t a b l e s , where t ' le t e m p e r a t u r e , a t l e a s t a t t i m e s , i s above 16°C. Such w i n t e r b r e e d i n g p l a c e s become t h e i m p o r t a n t f o c i f o r F l y i n f e s t a t i o n s t h e f o l l o w i n g s p r i n g . Even on some Swedish f a rms n o r t h o f t h e p o l a r c i r c L e p r o l i f i c f l y b r e e d i n g and i n c i d e n c e o c c u r a l l t h r o u g h t h e s e v e r e win:r-P i n w e l l i n s u l a t e d s t a b l e s .

O v e r w i n t e r i n g o f a d u l t f l i e s i s n o t l i k e l y t o be o f i m p o r t a n c e . A t t h e most f a v o u r a b l e c o n d i t i o n s f o r l o n g e v i t y , t e m p e r a t u r e s f l u c t u a t i n g between 5OC and 1S0C, f e m a l e s r a r e l y l i v e l o n g e r t h a n t h r e e t o f o u r months . However, S o v i e t i n v e s t i g a t o r s have fcund t h a t M. d o m e s t i c a can h i b e r n a t e i n a n i n a c t i v e s t a t e a s a d u l t s , and a s p repupae and pupae i n f r o z e n o r c o l d dung and s o i l . T h i s i s p r o b a b l y a s p e c i a l a d a p t a t i o n o f t h e house- f f :es i l t h e s e a r e a s . I n t e m p e r a t e China i t was a l s o b e l i e v e d t h a t o v e r w i n t e r l n g a s pupae p l a y e d a r o b e For t h e house- f l y i n f e s t a t i o n s and f l y pupae were c o l l e c t e d i n t h e autumn. Recen t i n v e s t i a g a t i o n s i n Ch ina have shown t h a t most ( i f n o t a l l ) o f t h e o v e r w l n t e r i n g pupae a r e of 7 t t re r f l y s p e c i e s , e . g + b l o w - f l i e s and f l e s h - f l i e s , which a r e known t o have a d i a p a u s e . T n i s IS a i s r Cound i n t h e l e s s e r h o u s e - f l y , Fann ia c a n i c u l a r i s , i n Europe.

111.4. B i o l o g y and b e h a v i o u r o f a d u l t f l i e s

The r e a c t i o n s and b e h a v i o u r o f t h e newly emerged f l i e s and a t matLrg a n d o v l p d s i t i o n have been d i s c u s s e d unde r S e c t i o n 111.1 .4 .

111.4.1 Feed ing

House-f ly ma le s and f e m a l e s c a n s u r v i v e w e l l on w a t e r p l u s s u g a r o r f ~ t h e r a s s i m i l a b l e c a r b o h y d r a t e s ; i n a d d i t i o n , f e m a l e s r e q u i r e p r o t e i n o r p r o t e i c c n m p o n e n t s <!amino a c i d s ) f o r t h e development o f e g g s , b u t n o t f a t and o t h e r i i p o i d s ( S p i l l e r , 1464). H o u s e - f l i e s f e e d on a l l k i n d s o f human food and g a r b a g e , on e x c r e t a i n c l u d i n g s w e a t , and on an ima l dung . They a r e p o o r l y equ ipped w i t h smell r e c e p t o r s on t h e a n t e n n a e ( e .g . compared t a b l o w - f l i e s ) and a t t r a c t i o n by odour t o food a t a d i s t a n c e p l a y s a minor r o l e . The food is m a i n l y found by e x t e r ~ s i v e random e x p l o r a t o r y movements of t h e f l i e s combined w i t h v i s u a l ac r r a c ~ t o n ( e . g . rc, d a r k s p o t s ) and r e a c t i o n t o h u m i d i t y and smell a t s h o r t r a n g e , a t which Eany o d o u r s show r f f 6 : c t ( b i d i n g , 1 9 6 5 ) . The h o u s e - f l y r e a c t s t o smells of f e r m e n t i n g artd p i r t r e fy i t i g m a t e r i a l s , t o a l c o h o l s , l ower a l i p h a t i c a c i d s ( e . g . a c e t i c a c i d ) , a l d e h y d e s and e s t e r s ( w h i c h %ay o r nay not be Lncluded i n "sweet s m e l l " , (Yamamoto & J e n s e n , 19679, b u t a l s o t o t o x i c s u b s t a n c e s s u c h as c h l o r o f o r m , fo rma ldehyde , and some o rganophosphorus i n s e c t i c i d e s ( M u l l a , e t a l . , 1 9 7 7 ) .

When i n c o n t a c t w i t h p o t e n t i a l food t h e h o u s e - f l y t a s t e s i t w i t h t h e c h c m o t a c t i c r e c e p r c r s on t h e f e e t and t h e p r o b o s c i s . These r e c e p t o r s a r e e s p e c t a l i y s e n s i t i : i e r i sc . . lu t ions s u g a r . I f t h e t a s t e i s good t h e f l y s t o p s , e x t e n d s t h e p r o b o s c i s and mar: start feedi r .g . L iqu id food is sucked up, b u t s o l u b l e food i n s o l i d form ( e . g . s u g a r ) must f i r s t b e w e t t e d an2 d i s s o l v e d by l i q u i d from t h e f l y ' s c r o p and s a l i v a . Orhe r s o l i d m a t e r i a l s may be s c r a p e d with t i n y t e e t h on t h e p r o b o s c i s . Sone c ~ m p o u n d < , e .g . amino a c i d s and guanoi ; ine miinophospirate, a c t a s f e e d i n g s t i m u l a n t s , i . e . i n c r e a s e t h e f e e d i n g , i n f ema le h o u s e - f l i e s .

WHO/VBC/86.937 page 1 2

Where a v a i l a b l e , p i g dung seems t o be t h e p r e f e r r e d and most f l y - p r o d u c t i v e t y p e of dung ( A s c h e r , 1958) ; h o r s e dung i s a l s o a n e x c e l l e n t f l y b r e e d i n g s o u r c e , b u t o n l y f o r a s h o r t t ime due t o i t s r a p i d compos t i n g p r o c e s s . F l y b r e e d i n g i n a c c u m u l a t i o n s o f p o u l t r y excrement has become a g r e a t problem i n modern e g g and c h i c k e n i n d u s t r y , i n v o l v i n g b o t h M. d o m e s t i c a and the l e s s e r h o u s e - f l i e s ( F a n n i a s p e c i e s ) . O t h e r k i n d s o f dung t h a ~ may p l a y a r o l e f o r f ly b r e e d i n g l o c a l l y i n c l u d e donkey, r a b b i t , g o a t , s h e e p , b u f f a l o , and camel . Dung i s o n l y s u i t a b l e f o r f l y b r e e d i n g i n t h e f i r s t few d a y s t o a week a f t e r d e p o s i t e d . AS a r u l e house- f l i e s do no t b r e e d much i n composted dung.

111.2.2 Garbage and w a s t e s from food p r o c e s s i n g

Garbage i n c l u d e s w a s t e s from t h e p r e p a r a t i o n , c o o k i n g and s e r v i n g o f f o o d , and market w a s t e s from t h e h a n d l i n g , s t o r a g e and s a l e o f food . I t i s a v e r y i m p o r t a n t s o u r c e of f l y b r e e d i n g , and i n u r b a n a r e a s i t i s t h e p redominan t s o u r c e f o r b o t h h o u s e - f l i e s and o t h e r s y n a n t h r o p i c f l i e s , p a r t i c u l a r l y b l o w - f l i e s , r a n g i n g from i n d i v i d u a l househo ld g a r b a g e through r e f u s e a t food s h o p s and m a r k e t s t o g a r b a g e dumps ( S c h o o f , e t a l . , 1954) . T h i s i s f u r t h e r d i s c u s s e d i n s e c t i o n V . 1 . F l y b r e e d i n g is n o t c o n f i n e d t o a c c u m u l a t i o n s of g a r b a g e , b u t can a l s o t a k e p l a c e i n s o i l mixed w i t h g a r b a g e o r impregna ted w i t h s eepage .

Var ious w a s t e s f rom food p r o c e s s i n g and i n d u s t r y may a l s o be a s o u r c e o f s e r i o u s house - f ly b r e e d i n g , e .g . i n connex ion w i t h c a n n i n g o f v e g e t a b l e s and f r u i t , b r e w e r i e s and d i s t i l l e r i e s , s u g a r p l a n t s , e t c . ( I m a i , 1984) .

P r o c e s s i n g o f f i s h and m e a t , a s w e l l a s t r e a t m e n t o f v e g e t a b l e s , o f t e n g i v e r ise t o s e r i o u s f l y problems. A l though b l o w - f l i e s a r e u s u a l l y dominant where a n i m a l p r o t e i n i s t h e s o u r c e , h o u s e f l i e s somet imes b r e e d i n g r e a t numbers; f o r i n s t a n c e i n s o i l h e a v i l y con tamina ted w i t h b lood , f i s h o r s l a u g h t e r o f f a l .

I n a g r i c u l t u r e , w a s t e from growing f r u i t o r v e g e t a b l e s , e .g. d i s c a r d e d t o m a t o e s o r melons, may be a b r e e d i n g s o u r c e of many h o u s e - f l i e s .

111.2.3 Organ ic manure o t h e r t h a n dung

I n some a r e a s , where f i e l d s a r e h e a v i l y manured w i t h o r g a n i c m a t t e r , h o u s e - f l i e s may breed i n g r e a t numbers i n t h e f i e l d s , p a r t i c u l a r l y i f t h e manure i s a p p l i e d i n lumps. Bes ides dung, s u c h manure may i n c l u d e exc remen t , g a r b a g e , f i s h - m e a l , b lood- and bone-meal, o i l - s e e d cakes , prawn d u s t , e t c .

111.2.4 Sewage

Under s u i t a b l e c o n d i t i o n s h o u s e - f l i e s may b r e e d i n sewage s l u d g e and s o l i d o r g a n i c was te i n open sewage d r a i n s , c e s s p o o l s , s e e p a g e p i t s , e t c . , o r i n sewage beds . Moreover , f l i e s can b r e e d i n s o i l w e t t e d by househo ld d i s h w a t e r , where a sewage sys t em i s l a c k i n g .

111.2.5 Accumula t ions of p l a n t m a t e r i a l

P i l e s o f d e c a y i n g g r a s s c l i p p i n g s o r g a r d e n compost heaps have been found a s impor t an t s o u r c e s of h o u s e - f l i e s i n some u r b a n and suburban a r e a s [ S i f v e r l y & Schoof , 19551, and i n r u r a l a r e a s f l i e s may b r e e d i n s i l a g e (Meyer & P e t e r s e n , 1 9 8 3 ) arid i n heaps o f o t h e r r o t t i n g v e g e t a b l e m a t t e r . Heaps of s e a g r a s s o r seaweed on b e a c h e s may b r e e d Stomoxys, t h e b i t i n g s t a b l e f l y and c e r t a i n o t h e r f l i e s , b u t r a r e l y h o u s e - f l i e s .

111.3. S e a s o n a l f l u c t u a t i o n s and o v e r w i n t e r i n g

I f no c o n t r o l measu re s a r e ucied, t h e f l y d e n q i t y i n a g r v e n l o c a l i t y w i l l g e n e r a l l y f l u c t u a t e w i t h t h e c o n d i t i o n s f o r b r e e d i n g and r e p r o d u c t i o n ; i n p a r t i c u l a r t h e a i r t empera tu re i n f l u e n c e s t h e r a t e of m a t i n g , t h e p r e o v i p o s i t i o n p e r i o d , o v i p o s i t i o n and f e e d i n g of a d u l t s . The tempera t t l re ot: t n e b r e e d l n g m<-dl8l-n i s ' i l so f d ~ t i i r , b u t i fetiiieili:i~E; hc;aps of dung* g a r b a g e , e t c . , a n o p t i m a l t e m p e r a t u r e w i l l o f t e n be r e a c h e d , even i f t h e a i r t e m p e r a t u r e is low. I n such s i t e s l e t h a l h i g h t e m p e r a t u r e s i n h o t p e r i o d s may l i m i t b r e e d i n g . I n t r o p i c a l

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and s u b t r o p i c a l a r e a s d e s i c c a t i o n o f b r e e d i n g media i n h o t and d r y p e r i o d s may a l s o r e s t r i c t f l y b reed ing . I n s u b t r o p i c a l a r e a s (e .g . Egypt) w i t h a v e r y h o t and d r y summer and c o o l w i n t e r , t h e r e w i l l o f t e n be a s p r i n g and autumn maximum a t mean t e m p e r a t u r e s of 20-25oC, a summer d e p r e s s i o n and low d e n s i t y i n t h e w i n t e r (Madwar & Zahar , 1953).

Even i n some a r e a s w i t h a t e m p e r a t e c l i m a t e i n v o l v i n g h o t summers, t h e summer d e p r e s s i o n may occur . However, i n most t empera te and s u b t r o p i c a l r e g i o n s t h e u s u a l p a t t e r n i s t h a t of a w i n t e r p e r i o d w i t h few t o v e r y few f l i e s , a g r a d u a l o r sudden i n c r e a s e i n s p r i n g , a summer f l y season o f t h r e e t o e i g h t months and a d e c l i n e I n t h e autumn. I n a r e a s w i t h a c o a s t a l t empera te c l i m a t e (e .g . nor thwes t Europe) t h e f l y i n c i d e n c e is c o r r e l a t e d w i t h t h e hours of sunsh ine and is depressed i n wet p e r i o d s .

Overwin te r ing . The q u e s t i o n of how house-f ly p o p u l a t i o n s o v e r w i n i e r , e s p e c i a l l y i n p l a c e s w i t h a c o l d w i n t e r , i s s t i l l be ing d i s c u s s e d . M. domest ica has no t r u e d i a p a u s e , and most i n v e s t i g a t o r s a g r e e t h a t , whenever p o s s i b l e , t h e house-f ly w i l l o v e r w i n t e r by s low breed ing i n b u i l d i n g s , p a r t i c u l a r l y cow s h e d s and o t h e r s t a b l e s , where *he t empera tu re , a t l e a s t a t t i m e s , i s above 16OC. Such w i n t e r b reed ing p l a c e s become t h e i m p o r t a n t f o c i f o r f l y i n f e s t a t i o n s t h e fo l lowing s p r i n g . Even on some Swedish farms n o r t h o f t h e p o l a r c i r c l e p r o l i f i c f l y b reed ing and i n c i d e n c e o c c u r a l l through t h e s e v e r e w i n t e r i n w e l l i n s u l a t e d s t a b l e s .

Overwin te r ing of a d u l t f l i e s i s n o t l i k e l y t o be o f importance. A t t h e most f a v o u r a b l e c o n d i t i o n s f o r l ~ n g e v i t y , t e m p e r a t u r e s f l u c t u a t i n g between 5% and 1 5 O 6 , f emales r a r e l y l i v e l o n g e r t h a n t h r e e t o f o u r months. However, S o v i e t i n v e s t i g a t o r s have found t h a t M. domes t i ca can h i b e r n a t e i n an i n a c t i v e s t a t e a s a d u l t s , and a s prepupae and pupae i n f r o z e n o r c o l d dung and s o i l . T h i s i s p robab ly a s p e c i a l a d a p t a t i o n of t h e h o u s e - f l i e s i n t h e s e a r e a s . I n temperate China i t was a l s o b e l i e v e d t h a t o v e r w i n t e r i n g a s pupae played a r o l e f o r t h e house- f l y i n f e s t a t i o n s and f l y pupae were c o l l e c t e d i n t h e autumn. Recent i n v e s t i a g a t i o n s i n China have shown t h a t most ( i f no t a l l ) o f t h e o v e r w i n t e r l n g pupae a r e o f o t h e r f l y s p e c i e s , e.g. b low-f l i e s and f l e s h - f l i e s , which a r e known t o have a d i a p a u s e , T h i s i s a l s o found i n t h e l e s s e r house-f ly , Fannia c a n i c u l a r i s , i n Europe.

111.4. Biology and behav iour o f a d u l t f l i e s

The r e a c t i o n s and behav iour of t h e newly emerged f l i e s and a t ma t i cg and o v i p o s i t i o n have been d i s c u s s e d under S e c t i o n 111.1.4.

111.4.1 Feeding

House-fly males and females can s u r v i v e w e l l on w a t e r p l u s s u g a r o r o t h e r a s s i m i l a b l e c a r b o h y d r a t e s ; i n a d d i t i o n , f emales r e q u i r e p r o t e i n o r p r o t e i n components (amino a c i d s ) f o r the development of e g g s , bu t n o t f a t and o t h e r l i p o i d s ( S p i l l e r , 1964) . House - f l i e s feed on a l l k i n d s o f human food and g a r b a g e , on e x c r e t a i n c l u d i n g swea t , and on animal dung. They a r e poor ly equipped w i t h s m e l l r e c e p t o r s on t h e an tennae (e .g . compared t o b l o w - f l i e s ) and a t t r a c t i o n by odour t o food a t a d i s t a n c e p l a y s a minor r o l e . The food i s mainly found by e x t e n s i v e random e x p l o r a t o r y movements o f t h e f l i e s combined w i t h v i s u a l a t t r a c t i o n (e .g . t o da rk s p o t s ) and r e a c t i o n t o humid i ty and smell a t s h o r t r a n g e , a t which many odours show e f f e c t (Ke id ing , 1965) . The house-f ly r e a c t s t o s m e l l s of f e r m e n t i n g and p u t r e f y i n g m a t e r i a l s , t o a l c o h o l s , lower a l i p h a t i c a c i d s (e .g . a c e t i c a c i d ) , a l d e h y d e s and e s t e r s (which %ay o r may qo t be inc luded i n "sweet s m e l l " , (Yamamoto & J e n s e n , 1967) , bu t a l s o t o t o x i c s u b s t a n c e s such a s chloroform, formaldehyde, and some organophosphorus i n s e c t i c i d e s (Mulla , e t a l . , 1977) .

When i n c o n t a c t w i t h p o t e n t i a l food t h e house-f ly t a s t e s i t w i t h t h e c h e m o t a c t i c r e e e p t o r s on t h e f e e t and t h e p r o b o s c i s . These r e c e p t o r s a r e e s p e c i a l l y s e n s i t i v e r o s ~ l u t i o n s i.f sugar . I f t h e t a s t e i s good t h e f l y s t o p s , e x t e n d s t h e p r o b o s c i s and may s t a r t Feedlcg- L iqu id food i s sucked up, but s o l u b l e food i n s o l i d form ( e . g . s u g a r ) must f i r s t be wet ted and d i s s o l v e d by l i q u i d from t h e f l y ' s c r o p and s a l i v a . Other s o l i d m a t e r i a l s may be sc raped w i t h t i n y t e e t h on t h e p r o b o s c i s . Some compounds, e .g . amino a c i d s and guanos lne monophosp%ate, a c t a s f e e d i n g s t i m u l a n t s , i . e . i n c r e a s e t h e f e e d i n g , i n female h o u s e - f l i e s .

1~ i ; a crtmmstrl e x l e < r i e ~ ~ c r t h , i t f - t , > d c . ) * l t a i : t i r ? g s u g a r o r s t a r c h becomes more a t t r a c t i , . . . + - i ..; wt..,? . . , t i ler f i i , s i; : v \ , 'ed 32 i t . The e ~ p l ; ? r ~ ~ a t i ~ > ~ - t i s t h a t t h e s a l i v a ; I € t h e F i rs t j

1s aoi i t i :it*d ;I:><: p,;rt ! v ? t i c )mp:>scd t h e f~t- i i ! t o i3rtdi11.t. ; r h a t a r e more t a s t y ( e . g . m a l t ;-tir.:si. a!?d f r6l;-..,\si.) i r ~ d .:., s p e e i F f c " l l y f a c t o r " seems t o b e i r ~ v o l v e d . I n a d d i t i o n .i:i~t !jf a g r - ~ u i , ,?F f l i e . . ~ t c r . i c t . ; . ~ t i ; e r t l ic . : ( t i l t . "herd i i l s t i r i c t " ) . Hungry f l i e s 1::1ve a t r:indom, b:lt w$e;=:? t i i cy have t a s t e d a s . n a l l amount of f o o d ( e . g . a d r o p o f I , l > r ? > t+*y : qt:, ., - ' - -, ~ i i e i r rcnrl.'; by n o c i : ~ g i:: c i r c l e s o r s p i r a l s . R e c e n t e x p e r t r

% :ls,re ; ~ ~ s . ) ~ ~ t!%.3: ! I G & ~ S % ~ --f: i a . s c' I:? l e a r . ? t ~ ) : i ~ s r > c i : i ~ d d i f f c r e i ~ t o d o u r s o r 1 i g h t s t i m u l i f l ed .

The d i s t r l b t i t i . , : ~ -5 ,rllll.tr f l i e s i i i t h ~ - > i r ! t a b i t a t is d e c i s i v e f o r t h e i r u n h y g i e n i c role fr j r t h e i r co: l t r t t ! . A"!': f L i ~ s a r e : n l v a c t i v e i n l i g h t , i n d a y l i g h t o r i n a r t i f i c i a l l 1.1 J , i r k , i e s s t ' l r y r . . ' r Y cr- iwl 41:1wl:;.

(a ) Dayt imp d i s : r t b u t i e n . F l i e s a r e m a i n l y g a t h e r e d on o r a r o u n d f e e d i n g a n d brec ------p -P

s*,urct..; whel-t. ~ , " i - z 3 ' 3 0 t a k e s p l a c e . A c t i v e p e r i o d s o f random a n d d i r e c t e d rnovem, I e + J t g , qa"_irig - ! * ; i t i t i n ' ire i t e r s p e r > e d w i t h r e s t i n g p e r i o d s .

The di.;lt S - i h i j r l I:: f l i e s b o t h when a c t i v e and r e s t i n g a r e much i n f l u e n c e d by r e : i t t i o r ? t o s u c h f a . - t , i ~ ~ 3 - 3 t ceap i? rq t i j re , h u m i d i t y , wind and l i g h t a n d t o c o l o u r a n d t e x t u t h e surf- icc+. A s :a r i : 7 r 2 t i t * ctayt ime r e s t i n g p l a c e s w i l l be c l o s e t o r h e f e e d i n g ( a n d bree t s'tii.ces, :h:' a ? ! - t - . i . : t i c v r !c wl;ich was d i s c u s s e d a b o v e . I n d r y w e a t h e r , w a t e r a n d m o i s t u r 6 srr ~ 1 ~ r - r i c tent ; l ?l?it .ins.*:li; fo .>d siil.rr::i?.; m i l k r's e s p t i c i a l l y a t t r a c t i v e i n most p l a c e s .

Yx!),-i.,nar?*- i,.i .l!l-!u-; -.he prtcterrt:d tempt.r : i t , r re f,rr r e s t i n g f l i e s t o b e 35-4006 ( a U°C fi :r r3cvly er,it>r i?ed f l i z .~s ) , Lettia:! e f f e c t ( h e a t p a r a l y s i s ) o c c u r s a t 45-47OC. Belorr 25!)C t h e rn<.\vernerlc s ?!id :>;i;i~r : ~ c t i v i t i e s g r a d u a l l y d e c r e ; ~ s e . O v i p o s i t i o n , m a t i n g , f e e d i n g "!i.ing i-iic3::.. : ~ r 1 Z - - ' ''.: :-*! crqwl :q:,vemp::t..; a t 7.-4!?6. The r e a c t i o n t o t e m p e r a t u r e may , : c : i : : 1 , 1 W 4 : S j .e i~d t : ~ r e a c t 3 h i g h e r t e m p e r a t u r e s v 3 , % , - . , ~ ! t I :; telti3er?:..i ~ r e i i s ) , I s-::.;~!:~iL 1 ; i s 3i.i:i;rding t o p r e v i n u s c o n d i t i o n i n ; h . P,.... . -,. L . ~ - a t , l r t : ~ . , 2t;? ' , : i c I ; - .~ : ! ' : ! (~r~: i"~ e - g . , ; i i " x - i t i ~ r i , s e x , a g e , m a t u r i t y , a s w e l l a s c e i::~:.iti,- i f - ,..g.. i l r ! n f 7 ~ t y a n d w i i l d , nay i i ? t l : ~ e n c e it. Althn , lgh t h i r s t y f l i e s

a t t r a c t i - c ' tc r n : i i s ? i i r : , ~-c-!nsr~-iLLi:c; o u i t e r a l l y p r e f e r n low a i r h u m i d i t y , a t w h i c h t h e y a r e lnnsr a ~ t i i ; . ~ ' r : c i " y ! f ; w i i t h a r F!ousc~-f l i e s ; rvnid e x p o s u r e t o wind a n d a i r d r a f t ,

i ~ r l e i s :t-:ln~,. IF^ ;.:A . . i t > t i c s ? a i r v e ? o c ! r j e ~ .

The r e a . - t - i r ? . . c* t ; ~ ~ t i ~ - ; . - f l i e s c o ?ig!lt- a r e ~ . o i n p l e x , much d e p e n d i n g on o t h e r f a c p h ; s s i c a l , 1 m c , ;tb:~.;i 1 1 - ~ g i i ; * L , e t ( :. A s I a e n t i o n e d a b o v e , t h e newly emerged f l i e s upwards (neg3ti .v .e g e o t a x i s ) , b u t g e n e r ~ r l l y t o t h e d a r k e s t p l a c e ( n e g a t i v e p h o t o t a x i s ) . 1

f i i e s <how no g e n e r a l a v o i d a n c e o r a t t r a c t i o n t o l i g h t . I n some s i t ~ ~ a t i o n s t h e y a r e a t t r . t o d a r k a r e a s o r rile b ~ ~ r d e r l . i i l e b e t w e e n l i g h t a n d d a r k , i n o t h e r s t o l i g h t a r e a s . Dist, or crowded E ? i + > r a l w a y s move 1-owards l i g h t . 4 t r e ! n p r r a t u r e s be low 270C f l i e s move t o S.

a r e a s b e c a u s e of t h e h i g h e r t e m p e r : l t u r e .

T'hc' r e a c t i o c s ( i f F i i e s t o d i f f e r e n t : cci:orirs h a v e b e e n s l ~ b j e c t e d t o num - . i .-ivesti;ra:io~1.;, w h i c h % ~ v e gi.x:c?n diver;. . r c c t l l t s ( f i e c h t , 1 9 7 0 ) . E x p e r i m e n t s w i t h c o l

.;?lrf.iees h a v e c,liown t h a t f l Le'; gecer : t l l i v c j i ~ i g l ' ) ~ , ; y l i g h t - r e f l e c t i n g s u r f a c e s . I n t i v h t - r e 211 t r n - v i o l e t l i g l ? t i s 3 :? rge iy r x t - l t l d e d j t h e y n s u a l l y p r e f e r d a r k s u r f a c e s , h l a r ti.rr-!C r-._!i, a n t i a.; 51 ~ " : i l ~ b l u e i s i i ld ' i t : ~ t t r a c t i v e , whert:;zs o u t d o o r s h o u s e - f l i e s may p . : - . : ] , W .p;;d i "-Id :L.'.' . ,.id 1 T!,i.c:ci r r e q2.t i t r o n g l y i n f l u e n c e , t e m , p e r n t : ~ r e . R c t h i ; > d i i o r r and o . : t d o ~ r s ti:e c . ~ i l t r ? s t b + c w ~ e t i t h e h;.,-kgrtt*lnd and t h e co l01 i c p > r t a i l t fsr i t s - t r t r - ic t ,3nc- . , T h i l+-ci- i-r ion c i f f i : ~ . s tc: Lsj:c):ired l i g ' r t i s a r i o t h e r ma I n g e n e r a l ?tot~.te-- i : ies : i r - i ~ o l . - i r ~ r i g l y at:.3-wt~:+iJ t a ) Iar~i; ( < l i ) ? r t fr,.!o t h e hea t attractant l i g h t - t r a p s , v d h e t i ~ e r wi-th ' ~ i s i b l e o r i t ? t r a - - l i o l i . t 1 igi-:t; c : j n t r a r y t o blow-f l i e s a n d many F l ic3s, and thr; ;it:r:icr i v e n e s s !)f i-he c ~ o i tsur i s in fL; :enc i~ i ! hy t l ' r a i r t-etnpera tcit-e. Thus g a n d r e d 1 igii t j r i t ~ i ; i ? s t i n g s o u r c e .>i h c > : ~ t ) nay he w j r e rittr-ic:tl:,c. a t r e l a t i v e l y low t e m p e r a ( 1 9°C) and Mt~il? i-jr 111. t ra-vial t ; t l igi:t m c r r ; i t t r a r . t i ; * c ; a t i > i g I i e v t e m p e r a t u r e s ( e . g . 28OC).

WHO/VBC/86.937 page 1 5

The t e x t u r e o f t h e s u r f a c e i s o f impor t ance f o r t h e c h o i c e o f r e s t i n g p l a c e . H o u s e - f l i e s t o s e t t l e on rough s u r f a c e s and a v o i d smooth o n e s , and t h e y h a v e a s p e c i a l p r e f e r e n c e

f o r e d g e s .

The g e n e r a l d a y t i m e d i s t r i b u t i o n of h o u s e - f l i e s d i f f e r s a c c o r d i n g t o c l i m a t e and h a b i t a t ( K e i d i n g , 1965) , c o n c e n t r a t i n g a r o u n d b r e e d i n g and f e e d i n g s i t e s .

I n wara c l i m a t e s o r s e a s o n s much o f t h e h o u s e - f l y p o p u l a r i o n s p e n d s t h e day r ime o u t d o o r s o r i n cove red a r e a s n e a r t h e open a i r , such as marke t p l a c e s , b a z a a r s , s h e d s and v e r a n d a s , and ~ h ~ p s , r e s t a u r a n t s and rooms w i t h a n open f a c a d e . When n o t on food o r b r e e d i n g s i t e s most f L e s a r e found or, t h e g round i n Low v e g e t a t i o n , on f l o o r s , t a b l e s and o t h e r h o r i z o n t a l s u r f a c e s . However, a t t r a c t i v e i n d o o r p l a c e s , p a r t i c u l a r l y k i t c h e n s , p r i v i e s and an ima l s h e d s may a l s o have a h l g h day i n c i d e n c e o f f l i e s i n warm c l i m a t e s . Moreover , on h o t , sunny d a y s f l ~ e s may aove i n t ~ t h e - o u l e r h o u s e s , e . g* when s h a d e retaperat lure r i s e s above 30°C ir, t h e middle o f t h e dav.

A t t h e o t h e r end of t h e s c a l e i n t e m p e r a t e summers o r c o o l s e a s o n s most o f t h e h o u s e - f l i e s mav remain i q d o z r s , e s p e z i a t l y on wet and windy d a y s , and o ~ l y l e a v e b u i l d i n g s f o r s h o r t p e r i o d s , the dmount and 1ota:ion o f s u n s h i n e o e i n g o f g r e a t i m p o r t a n c e . I n r u r a l a r e a s f l i e s c o n c e n r r a t e i n s h e d s and s t a b l e s of domes t i c aanimals, p a r t i c u l a r l y c a t t l e and p i g , and t h e y speqd most o f t h e day on t h e warm s k i n o f t h e a n i m a l s o r on p a r t i t i o n s , e t c . n e a r b y ( F i g . 7 1 , bu: n o t u s d a l l y on t h e f l o o r and n o t Ir, t h e uppe r h a l f o f :be room.

F . D i s t r ~ . b u t : ~ ~ -E h o u s e f l i e s i n a Danish p i g g e r y by J a y ( t o p ) and by n i g h t . Each d o t r e p r e s t i q t s 1 7 -f t h e f l i e s and t h e d i a g r a m shou.s t h e a v e r a g e c o u n t s o v e r s e v e r a l summer d ~ v s . Such c o u n t s h a v e been t h e b a s i s of s t r a t e g i c f l y c o n t r o l .

WHO!VBC/80.937 p a g e L6

( b ) N i g h t - r e s t i n g h ~ b i t s . Towards d u s k t ~ ~ ) t ~ s t . - f l i ? s l e - ~ v t . t h e i r d a y t i m e p l a c e s <, a c t i v i t y o r r e s t anit m,,ve r : s p e c i a l night-rrS:c: :g sitis (:1.:;? b y . 1-r 9;ir-i : l in ;a t t . i !?

.;c.as;-. , 2 .g . w i t h 1:ig" :e;z;.cr+::iri=s ,it;-vi. l""t', .X . - ~ ; : ; i d e r ~ l . : ~ i ;:c ' . L : ., .>f : ~ i l i l ~ p - f l r e r e s t s :;u;daors o n t w i g s -i:~d l ~ . i v e s of t r e e s , i k ~ t i h ; vnd h e r b s , 0.1 wire.;, + + n c e s a n 3 o;b+ i l a r r o i j o b j e c t s a n d e d g e s , c f t i i r : twi ; 2r mare c c t r i ? ; ah.:e t h e gr:.17J ,112 : r t , t e iczLi f r a n w i n d

( Y n i r r , 5: a l . , 1 9 5 2 ) . ii+;wex;sr, even 3:i * i r ~ : : icbts T ; Z : I ~ hoi:sr?-f!it>; r e s t s q d e r ~ o * : e r L . , , l , c ~ . ~ ~ ~ ,, , 3 , : , e - j , r I , iw? :ng i . - s ~ c - . . S ) - : > I ~ ; e t 3 - - I- ,.,-:a ., r - X odi!ji,- . ..

5 . ; , 7 . , 5.1 - 7 - I : ;rfi n*:ar. ;::e cei!ii; ~r a ; l e - 1 s t w e l l a b o v e t h e fL.:or, a n d t h e f l i e s s i , w s t r , :ng preferc?::.?: 5:i.r w : r e s , c o r d s jn ,,:theer nsrrjw i ~ b j e c t s , espc'c i ? ; l y ~ ~ e r r i l i l a l <ir:is, i r3 f . i r e d g e s , ;?ra.~zl-;.~~,- ai?d i r r e g u l a r i t i e s . * * T'I* f a ~ ! : ~ : + J q i g h t - r e ; t i n g ?la:fis i r e recc,gn;z..a oy t i n e i r t h i c k cci*:r~ >K-LY e x c r e m e n t . 3 c,?\c71er n i g i r t s w i t h m ' r - t i m : i r ~ t t i ? l ~ . ; r a t d r e s 5e:uee- 15-2L7J6 p i r t of :'-e ;(l;l,il.i"iion mn;r s t i l l . ) i i t d c o r s , b u t more f l i e s W-.;. i ;?.3oors. T h e r e i s ?o s k a r p kmpperat:rre : i a i t ft3r i n d o o r 3

o i x t d w r r e s t l q g , a n d t h e r-iActi8;-? :c t e z p e r a t i i r e a a y v a r y from o n e ciizatic: z o n e t~ t h e o t h e r , . ic t h e t e m p e r a r e summer <iII f l i + s r e s t i n d o a r s .*L n i g h t , ? . g . i n C ~ W ; C + J - 'r p i g g e r i e s , p s r t l

i n t h e c e i l i n g a r e a , b i ~ t RI.;$) st l i v e r p o . ; i t i o n s In p a r t i t i o n s , ere- i F l g , 7 ) .

X details-4 k n o w l e d g e . , f l,>;?! . ~ i g h r - r e s t i : - , g -1.-:es I s " ;port<int f - i r - i t i < , ~ a 2 f l y c o n t r o l .

!12 ,4 .3 D i s p e r s i o n * -

H o u s e - f l i e s a r e good f l y e r s and c a n move F . r w i r d 3t 2 r a t e ,:C c - ? k m p e r h o u r , b u t t h e ar* n o t m l g r a t s r y b y n a t u r e a n d d o n o t n o r m a l l y embark upon 10-g ". i , g t t s . They move a r o u n d g r e a t J e a l t ? e x p l o r e tbt?:? ; . : v i r ~ i : i n r n r , b u t a s :;-?g a; :>.:v fi:?:! : i - : ; f ~ k ' i ' ~ i l d s u f f i c i e n t food b r e e d i n g s i t e s a n d s h e l t e r t hey :e:id t o rtiinaiq u k h i i n a r : ld ius :)f :?r:--5;"" m f r ~ ~ a t t re b r e e d i n s i t e . However , i n f a v i ~ ! i r . i h l r -xz.rt):er soz;. ,)I_ ~ 5 e r, ,u.;e-f1ies " 7 - . r -1 "or~lls m,3y d i s p e r s +-., I , s p e c i a l l y i n c.;se . j f ; ~ e r p ~ j p ~ n i a t T . ; ~ ~ ,>Q :i,e b r i - e d i n g $5- . be f ,.:::L ~n s i t e s 3 a t t r a c t i o n 1-5 km o r n o r 2 a v i 7 r i - i -:!;.?age .>I. C W R , o c L=; neij;i-Sc>.:rlv-< i L ? a g i ? s :- f ? r m s .

\?I.I*:~ 3 F ghe inf : j r : r? ,~t l*,v- :n F:.: ~ ~ s ~ L ~ ~ s L . ) ~ :i; ha^--(: :I i , r a ~ ; - : ;F -*:;C& houqe--C3 A L Z ~ S ' 5 . -

; .ari(lus d i s t a n c e s F r o 2 t h i i ~ r p~iz: ?f r r r lbea . ;e , a ~ c i ii; .= 2;;; .*:<per: B-.-r.: s:me - I !CS w e r e foui:d u t o 10-20 km away ( S c h o o f , 1 9 5 9 ) . Tlresr r e c o r d s shtiw t l ; a t som.2 'r.:lr3;.-fYii?s qay t r a v e l g r e a d i s t a n c e s , b u t t h e y a r e e x i e p t l o n ~ , a n d i r i s not c l e a r :: what 2u-tz-.r :hey flew by t h e m s e l v e :)r t r a v e l l e d by c a r , h o r s e , c a m e l o r o t h e r v e h i c l e . T a s s i v e t r . ?ysp . - r t ob" L l o i ~ s e - f Z i e s o v e h i c l e s , f rom t h e g a r b a g e t r u c k ta b u s z s a n d p r i v a t e c a r s , e t c . , Jce; ;>lay a n i m p o r t a n t r o l i n t h e i r d i s p e r s i o n ( W h a r t o n , e t a l . , L962). :-towever, I i 2 u s e - f l i e s a r + > a:i .rtalrikji a b l e t o f l c o n s i d e r a b l e d i s t a n c e s , p a r t i c u l a r l y i f l ~ f t i n o p e n conn:ry wi"_~o;: t ;i t e s o f a r t r a c t i o n (an d l 5 ~ r a c t i u n ) p r o v i d i n g f o o d a n d s h e l t e r . Some i n v e s t i g a t i o n s h a ~ ? ;':..-A-: a t e n d e n c y o f house f l i e s t o f l y a g a i n q t a moderat ;? w i n d , 2-12 krr;/h, c a r r y i n g 3 t t r a c t i v i . -.'.>urs, e . g , f r o m a d i r t f q rm , b u t i n o t h e r r a s e s f l i e s ?loved w i t h o r a c r o s s t h e d i r e c t i o i i of the wind ( P i c k e n s , 5 a l . , 1967) . --

IV. PUBLIC HEALTH IMPORTANCE OF HOUSE-FLIES

IV.1. P o t e n t i a l of f l i e s f:>r t r a r ~ s w i i ; s i t ; n o f d i s e a s e --pp-----.---- -

S i n c e t h e b?ginni!:g !?f t h i s c e n t ~ i r y Y. domez; t i ca h a s betan regar-l<.ti is ~:,:;.:;t-ial an -P

o f t ~ 1 7 impor tdr l t ager i t for r r a r r s m i s s i o n of s e v e r a l e n t e r i c * i n f e c r ; o r , s s:~:-i; +i: J:;t.:lterieS i n f a n t i l e d i a r r h o e a , t y p h o i d , f o o d p o i s o n i n g , c h o l e r a a n d h e l n i n t h s * 2 n d : he f l i p s have bee a c c i t s i ~ d o f t r a n s m i t ? - i n g l e p r o s y , p o l i o m y e l i t i s a n d c e r t a i n s k i n j;sc:l.;e.: c!;[:'rr as yaws* ; ~ h I l e M N. s o r b e n s has b e e n r e g a r d e d as i m p , , r t a n t fcir r h e s p r e a d O F I-a i r f * i : t l i _ ) i : ~ . Recr .nt l l i s y n a n t h r o p i e f l i e s o t h e r t h a n Musca s p e c i e s , e . g . many s ; t e c i r :-if h l r i w - f l i e ~ , F : ? . J ~ r - c c e i ~ e a t t e n t i o n %c; p f 3 t e n t i a l t r a n s m i t t e r < ; o f e n t e r i t i n f e c t i o n s (Grect~bur- , , I l i T i ) , Ti?-:*t. c i - ~ ~ i r g e a g a i n s t f l i e s o f s p r e a d i n g d i s e a s e s r e s t on rile f ~ : ! L ~ w i ~ ~ p t rb ' i e rc? t ig r : s :

f 1 ) i i ~ i i s e - f l i e s and o t h e r s y n a : ~ t h r i . p i c i - ' l i e s ctjme i n t o c a n t i i c t b o t h j ; i r [ l <!jh.ic-ratt2 (q;icit a f a e c e s and (it}-$er e x c r e t a , c a r c ; & 3 s e s , g a r h d g e 3113 o t h e r filthy -n-ttr:-;r) t ! ~ a r may c o n t a i p a t h o g e n s * and then w i t h hltman b r i n g s , t h e i r food and ~ ~ t e n s i i s * , e t c . ( F i g , H ) .

FJHO/VBC/86.937 page 1 7

( 2 ) F l i e s have been shown t o p i c k up and c a r r y many pa thogens ( v i r u s e s , b a c t e r i a , p r o t o z o a , eggs and c y s t s o f h e l m i n t h s , e t c . ) b o t h e x t e r n a l l y , on t h e i r n rou thpa r t s , t h e body and l e g ! l a i r s , and s t i c k y pads ( p u l v i l l i ) o f t h e f e e t , and i n t e r n a l l y i n t h e i r c r o p and i n t e s t i n a l t r a c t .

As a r u l e pa thogens p i cked up by t h e l a r v a e a r e n o t t r a n s f e r r e d t o t h e a d u l t , and most p a t h o g e n s p i cked up by a d u l t f l i e s d o n o t m u l t i p l y i n them. The germs on t h e s u r f a c e of t h e E l y o f t e n s u r v i v e o n l y f o r a few h o u r s , e s p e c i a l l y i f exposed t o s u n , whe reas pa thogens c a n Live f o r s e v e r a l d a y s i n t h e c r o p and g u t o f t h e f l y and be t r a n s m i t t e d when t h e f l y vomi t s o r d e f e c a t e s ( d e p o s i t s f l y s p e c k s ) .

( 3 ) Expe r imen t s have shown t h a t p a t h o g e n s c a r r i e d by f l i e s unde r c e r t a i n c o n d i t i o n s c a n i n f e c t f o o d , a n i m a l s and man.

( 4 ) I n many c a s e s t h e i n c i d e n c e o f e n t e r i c and e y e i n f e c t i o n s i s a s s o c i a t e d w i t h t h e l o c a l o r s e a s o n a l abundance of f l i e s .

Fig. 8. H o u s e - f l i e s a n d o t h e r s y i t a n t l ~ r o p i c f l i e s rorne i i r t o c a n t a c t with s u h s t r - t t ~ that inay c o n t a i n pathogeric;, and t h e n w i t h human i;c.i.lgr ti-rroligh food , ~tensils e t c .

(5) -;\?me ;di;es 2 f r s c t i v e f l y c i ) i l t r ~ l has ?a i i s r t i n :?ir.ct- r e d u c t i o n i n t h e i i l c i d e n c e o f t!

dise;rc;i?.

-, !hert. ,i-i> n:ii-y i - . > ~ s ~ ~ b i ~ i ~ i e s ftrr f:irs to tra11::port ,*rid i i?ei .h-tni; . . t l i) . t Y i l i ~ l I l i t ~ < ~ t . i > ' 3 g ~ ~ ~

1;F,i,31iV b.c;;:ciJ!~te: w i t ! ? a l o w q(- , r l?dar t l 31 i;ygici12. !!o~ev;..:, i n clicir s i t t ~ a t i l ) : i t h e q u e s r i o n , , f r ';h.? i s fitr s;;ireatii:~;~; i !ifti:t ~ J I I S i t r i-o~npar~.i! t o o t h e r ways l

rr ; i i iain~~si l i ; i , r . , ge riire:;t:y by food, w z t e r , a i r irr d i r t y f i n g e r 5 ;itid o t l i e r d i r e c r c :on tac t e r i person to perd.ji t , ; ~ h i g t o dilr)r!?rr i j i i t j s t i . ) i ~ : w ! ~ t f ~ ~ t o r s i n f l u e n c e t h e t r a n s m i s s i o n dise; iSe i)y f j i t ? s ? For e:ltc.rii. d i s e a s e s :!ie folLowing f a c t o r s ~ony be aerr t i , i r led:

( 3 ) 'Tlir ilu,nber o f f l i e s t h a t come i : l t u contac t b o t h w i t h r e s e r v o i r s o f p a t h o g e n s (e.g o p e n l a t r i n e s :,r s e w a g e ) a n d w i t h f o o d , u t ~ ~ n s i l s , i;ti:.

( b ) Tile a v e r a g e iiu~nber o f p a t h o g e n s c a r r i e d by e a c h

( C ) The o p p a r t i ~ n i t y o f p a t h o g e n s t o m u l t i p l y i n Food i n f e r r e d b y f l i e s .

( d ) Ttie number o f p a t h o g e n s r e q u i r e d r o d e v r r o p i n f e c ~ i o n i n man.

F a c t o r ( a ) is d e p e n d e n t o n a c s . r i b i n , i t i o n o f r e v e r a l f a c t o r s , e .g . :

) The ahtin,lance o f f l i e s , d e p e n d e n t on p o s s i b i l i t i e s f o r f l y b r e e d i n g , a t t r a c t i o n f r c o t t w r ireas, t h e c l i m a t e , seaso t1 , e t c .

( f ) T i l t h i h i t s of t h e f l i e s irn a p a r t i c u l a r . ; i t u a t i o n a r e d e c i s i v e f u r t h e i r a b i l i t y t t r a n s r n i t i n f e c t i o n s . P o p u l a t i o n - ; t h a t a r e a t t r a c t e d b o t h t o e x c r e m e n t a n d otht- f i l t h ( e s p e c i a l l y i f t h e y f e e d on i t ) and t o food a r e most d a n g e r o u s .

The a t t r a c t i o n o f h o u s e - f l i e s : t o human f i e c e s inay b e s t r o n g i n t r o p i c a l a r s u b t x o p i c s l r e g i o n s , b u t i s much l e s s i n many t e m p e r a t e a r e a s . The c h a n g e s C

- l i w t e 3 ? c o p l a y ail i i n p o r t a n t r o l e f o r t h e p o t e n t i a l 9 f F l i e s t o s p r e a d d i s e a s e , nc o n i y as i t a f f e c t s t h e s e a s ? o a l p r e v a l e n c e o f t h e f l i e s , b u t a l s o a s i t may a f f e c t t 2 L r ) i ? b i i t s . N o e l s e - f l i e s may f r e q r i e r i t t i o u s e s i n c o l d w e a t h e r , b u t t o a g r e a e x t e n t I-tiinrtin o u t - o f -door5 i n w a r m p e r i o d s o r lLr:ates.

( g ) Thib ? r w i r n t ?E . i r r f e s t e d m a t e r i a l ( e x c r e m e n t , s e w a g e , o f f a l , e c c + ) e x p v s e d a r :rv::itnfile t t ~ tilt? f l y . T h i s i s o b v i o u s l y a v P r y i r n p c ~ r t ~ t n t . f w t o r .

( 1 ) The i.a;to;Lt'e O F f o o d , k i t c l t en 3 . 1 t e n s i l s , e t c . , t o t h e f l i e s *

t r i i p d j c;tfr?<.e l ; ~ t ~ ~ ; ~ l j - i t h e j n f e s t e i i materi.11. ( g ) a n d ki t .c*herts , r ~ s t , : u r : i n t s , 5tlop" Ft; xi--:n;irker_s, e t # ' .

(3) Tile rsi:Jl;ii; i;f .ii.tit:its nrld d i ~ p e r s i t ! o f the, f i i e s ( b o t h b y a c t r i v e f l i g h t a n d p a s s i v triir!st?ii~ t h y c n r s , e t c . (see s e c t i o n I l T , h . ? , thove) .

Most g?: t h e co::rli t i c t i ~ s f;rvorrriilg f l y ibi~ilii.?rtri* ,311d t:ransmissi.:,n o f d i s e a s e by f l i e s a r the r e w : r .?I $ ; ' W ;-ail.";ird o f h y g i c n e arid e n v i r a ~ : ~ i i l e n t , i l s a ~ ~ i . t a t i : > n , w h i c h , hi twevry, Fi-,,*ir:~ ':t!?er i:snn; ? f t c : , ~ ? s : n t t L i n g e n t e r i c : disi":xsci;. Thr;s i : shii:ics r ) f n z i ' l i i i ciiarr!loea 4 i se<-i.;i-r a d ? ; i q ( ? r y g i n V e n e z u e l a n villages (bJ.>if C , e t -- a l . , - !.969), t h e mai conc l :is i-:?ns w e r e :

wao/vac/s6 .937 page l 9

( i i ) Of t h e s a n i t a r y m e a s u r e s t h a t can be t a k e n , t h e p r o v i s i o n o f u n l i m i t e d amounts o f good w a t e r seems t o be c o r r e l a t e d w i t h t t ie most i m p o r t a n t r e d u c t i o n o f d i a r r h o e a i n c i d e n c e .

( i i i ) Pa thogens s u c h a s S h i g e l l a * and Sa lmone l l a* c i r c u l a t e i n t h e community p a r t l y because o f t h e i r t r a n s m i s s i o n by El. ies .

( L v ) Foodborne d i a r r h o e a c a u s e d by S h i g e l l a o r S a l ~ n t r n e l l a may b e a r e s u l t of t h e t r a n s m i s s i o n of pa thogen t o food by f l i e s , and t h e s u b s e q u e n t m u l t i p l i c a t i o n o f t h e pa thogens i n t h e food b e f o r e i t i s consumed.

I V . 2. Impor t an t d i s e a s e s t h a t may be t r a i ~ s m i t t e d by nan-bit in& f l i e s u n d e r c e r t a i n c o n d i t i o n s

F o r none o f t h e s e d i s e a s e s a r e f l i e s n e c e s s a r y and t h e y a r e r a r e l y t h e most i m p o r t a n t a g e n t f o r t r a n s m i s s i o n .

D i s e a s e s o f t h e i n t e s t i n e

B a c t e r i a l i n f e c t i o n s

S h i g e l l o s i s - b a c i l l a r y d y s e n t e r y and o t h e r d i a r r h o e a 1 d i s e a s e s . Under u n s a n i t a r y c o n d i t i o n s f l i e s inay be i m p o r t a n t ( s e c above ) . A s f e w a s l00 S h i g e l l a - b a c t e r i a may c a u s e i n f e c t i o n i n man (Bidawid , e t a l . , 1978) .

S a l m o n e l l o s i s - typholid, p a r a t y p h o i d , e n t e r i t i s , food p o i s o n i n g , e t c . F l i e s may p l a y a r o l e i n i n o c u l a t i n g f o o d , b u t Ln g e n e r a l t h e y a r e l e s s i m p o r t a n t t h a n i n S h i g e l l o s i s . The i n f e c t i v e d o s e n f S a L m o n ~ i l a - b a c t e r i a i s u s u a l l y much h i g h e r t h a n i n S h i g e l l a .

C h o l e r a - t r a n s m i s s i o n by f i i e s i s p o s s i b l e , b u t : ~ s u a i l y u f Ii t t l e p r a c t i c a l s i g n i f i c a n c e ( E c h e v e r r i a , e t a l . , 1 9 8 3 ) -

* C a m p y l o b a c t e r i o s i s - i t h a s " n e ~ shown ;In Norway t h a t Musca d n m e s t i c a may p l a y a -W-=--

l i n k i n g r o l e i n t h e epidemicj logy o f Campylohacter f e t u s j e j u n i - (Rosiif & Kapperud, 1983).

P r o t o z o a n i n f e c t i o n s -

Amoebic d y s e n t a r y - f l i e s may t r a q s m l t c y s t s , b u t see3 usua1;y t o he o f r e l a t i v e l y l i t t l e impor t ance .

H e i m i n t h i c i n f e c t i o n s

F l i e s do c a r r y e g g s and c y s t s of many i n t e s t i n a l . worms: piaworms ( E n t e r o b i t ~ s ) , roundworms ( A s c a r i s ) , whipworms ( T r i c k i i i r l s ) , ---- hocrkworrrs (Ar,cy7-osr~?ma W a n d N e c a t o r ) , s t r o r r g y l o i b e s , tapeworms (TaenLa, D i p y i i d i u n , e t c , ) and may i n s tme c a s e s c o n t r i b u t e t o t h e s p r e a d of h e l m i n t h s t o man and a n i m a l s ( D i p e o l u , 1 9 7 7 ) -

V i r u s i n f e c t i o n s - F o l i o m y e l i t i s and r e l a t e d v i r u s ( e , g . Gocksack ie and ECHO v i r u s e s ) d i s e a s e s - f l i e s a r e a b l e t o t r a n s m i t v i r u s t o human f o o d s i n q u a n t i t i e s h i g h enough t o c a u s e i n f e c t i o n i n some s i ~ s c e p t i b l e p e r s o n s , b u t g e n e r a l l y f l i e s a r e n o t c o n s i d e r e d i m p o r t a n t f o r t h e s p r e a d r s f p o l i o m y e l i t i s .

L ikewise , L t i s u n c e r t a i n w h e t h e r h o u s e - f l i e s a t h i g h d e n s i t i e s and i n u n s a n i t a r y c o n d i t i o n s may c o n t r i b u t e t o t h e s p r e a d o f i n f e c t i o u s h e p a t i t i s .

R ; . - k e t t s i a l i n f e c t i o n s

Expe r imen t s have shown t h a t C o x i e l l a b n r n e t t i i , t h e r i c k e t t s i a c a t i s i n g Q-fever , c a n remain i n f e c t i v e f o r t h e l i f e t i m e of h o u s e - f l i e s t h a t have been i n c o n t a c t w i t h t h e pa thogeq ortce (Hufko , i 984) .

WHO/VBC/8b.93? page 20

Tractlt;ma ( v i r a l 1 ar:il epi i i e l a i ~ . ~ . ~ ) ' L ill! ' L I v ~ l. is l! at*;?) - ?fusc.i s o r b e r ~ s i s s t t,,r,i - . - - - - . - - ~ ~ - - " - " - ~ - - _ _ - ~ " . - _ I . . ~ . . --.A&-.' '- .I-.-xI -..- -- ----. -W--- -- -* --- - -.- a r t r a t . e r i t r o i r t ie i . t r .d v ::es ,i:td i t 3 ; i ~ i s ,ii! ~ I r e sec r ~~c i i,i:s. ; t i 3 . o : ; s i i i e r ~ 4 ; i ~ ! p ~ ! i ~ t ~ , ~ t f

tile tzficlsmist;~.:)i :)t ~i;,biie eye i ~ ) F b - _ : i ~ j - ~ + ' i l l ? t i l e < r s l r ~i f l i e s : i t l .at ive t o ? r , i i s : i i s s : b y pf:r-;,,i:ai ,\,v1 i;.: .faay d i f :'er gr-d,ibi:r 3T,is~ . , ; I , s i " i ..i[.!ri:: t : ~ erre r>!:!+r, ancl [ n i v ;t j f f ir: t :r ' f J c?v,l: i:?p:., Xi:sc.a d,:iat.st ir,a i.; , s l :;o f:t,iiid .>{I irr!"ri:tL:d tzyi?-;, h u t see;.; t~ - - .- - - - -- less i i : t i~ortal l t t);,ii: 3. .;otFtt:ns, ijiiere ! ~ t , e i i S ; , : - , I?.: t i c . : t i + . ( J i . : i r t ~ , ~r a: - , 1 9 7 h ) . ' ' I -- --

: L i h < : i ; i i CQi!oropiJ..ie, -?re a l s o c:jtisi,te: gnat -s" , smal ! !??i i i . th ' ' --. t r :+ ; l sn i t t i . r s o f 3 .~i. l , i i : I ; i x r dme ,? * :~ :, L . i i ib t r , ? i> i i , . a l ( S i p h ~ 1 i i ~ ~ 1 1 Z t - t ~ ) S -.-- -

L n f e c t i o n s o f s k i n ,ir~ci wounds -a-- ",-.----- ----

F l i e s a t t r a c t e d t o s k i t ~ : i i iec t"Li?s and x o ~ n d s ~ * r e a b l e t.o t rdnsbni t i n f e c t i i i c i s S I . I C ~

c t r taneous d i p h t l i e r i a , iiiyro-ies, y~3ir.s a d L e p r o s y (Geciter , i975), birrt., klgdin, t h e impor tance f l i e s is u n c e r t a i n .

LV,J. F l y nu+-sance "W-"

The i m p o r t a n c e o f t h e lzu isance c r e a t e d by t n e p r e s e n c e o f f l i e s i n g r e a t o r tnoder. tiurnbers s h o u l d n o t be u n d e r e s t i m a t e d . F l y r ru isance becomes more i i ~ t o l e r a b l t ? a s econor c o r ~ d i t i o n s improve , b u t i n communi t i e s w i t h a low s t a n d a r d of l i v i n g , t h e c rowds o f f l i e s , t o t h e heirden o f d a i l y 1iCle. They d i s t u r b and t r o l i h l e p e o p l e b o t h d u r i n g work, a t Leist t ime and when t h e y want t o res t , F l i e s s o L l t h e i n s i d e and ou t - s ide o f houses . They have psycho log ica l . e f f e c t n o t o n l y a s a nir isai lce b ~ t t a l s o a s t h e i r p r e s e n c e i s a s i g n of t~nhyg ie i c o n d i t i o n s . T h i s d i s c o u r a g e s p e o p l e from k e e p i n g a good s ta txdard o f p r r s e n a l hyg iene , c l e a n l l r l e s s i n and a round hornes, artd t h u s a f l y problem inay b o t h d i r e c t l y arid i n r i i r e c t l y ham, itaprovement o f g e n e r a l t ~ y g i e n e . F i r r a l l y , f l y r lu isance may h e an ecorlomic problem, a s s t r o n g l y a fFecCs t h e t o u r i s t t r z d e . In d a i r y 'barns , h o u s e - f l i e s by annoy ing t h e cows I

r e d u c e t h e m i l k y i e l d .

V. FLY CONTROL

V . I . E n v i r o n m e n t a l sanZtatfon and h y g i e n e ----pp--.--.p

To o b t a i n long-- te rm c o t i t r o l * a.,i i i ies i 11 $11 baa ,ire is , villages, and ) t h e r i e t t l r m e i n c l u d i n g i n d i v i d u a l f a r m s , improved c n v i r o n m e n r a l s a n i t a t i o n i s ~ b s o l r r t e l y fundamen ta l , t h e m i c a l f 1 y conr r o l carl on1 y tie a suypletnelit e o s a t r i t ~ r y mrasurt-S [B*lrvfrre, 1980; K r i d i 1974), T h i s hasl lc 1.1 Lnc l p l e a p p l i e s p a r t i i * n l , 3 r t y t~ r e g i o n s w i t h a warm r f i m ~ t e ,

T h e o b j e c t i v e s of f l y c o n t r o l by s;-r;mi t a t i ! i r , a re :

"7. - L G e l i n i l n a t e o r r e d u c e f l y b reed i :~g (1) by c l i n i n a t i n g s o u r c e s ~ * ~ ; i r : ~ t , l e f o r f l y hrccid ( 2 ) by exc l i rd i ~g f l i t18 (previ511t egg.-l.;iyiiig) frc.m p:~te i l t . i , t l b t . r r ~ c l i n g s?iir,res (;i-i.;t.d . . t ~ x c r e t a ) and ( 3 ) hy C.? Llliilg l a r i i it: I n ; ? : f e . ; L c d : n a t e r i ; t I i ;

WHO/VBC/86.937 page 21

( i ) Accumulation of animal excrement (and f e e d ) c a t t l e , p i g , h o r s e , donkey, sheep , g o a t , r a b b i t , p o u l t r y , e t c .

Farm and domes t i c an imals do nu t o n l y occur i n r u r a l a r e a s , but a l s o may be found i n towns and suburbs , p a r t i c u l a r l y i n connexion w i t h s l a u g h t e r h o u s e s and l i v e s t o c k markets .

( a ) I n animal s h e d s , s t a b l e s , pens o r f e e d - l o t s . Dung and u r i n e t o g e t h e r wi th s t r a w and o t h e r bedding on t h e f l o o r o r mixed i n t o t h e s o i l . I t r e q u i r e s f r e q u e n t , p r e f e r a b l y d a i l y , removal ( P i c k e n s , e t a l . , 1967) , o r a s o l i d impervious f l o o r w i t h d r a i n a g e .

( b ) I n p o u l t r y houses. Accumulation of d ropp ings under cages o r net-bottoms should be f r e q u e n t l y removed and f l u s h e d c l e a n o r mixed wi th l ime and d r i e d .

( c ) Dung heaps. Composting (Gotaas , 1956) t o k i l l f l y l a r v a e by f e r m e n t a t i o n h e a t . Composted manure i s g e n e r a l l y no t s u i t a b l e f o r f l y b reed ing (Eastwood, e t a l . , 1967) . The dung i n t a n k s should be covered by p l a s t i c s h e e t s (Eastwood, e t a l . , 1966) , s t r a w , s o i l , e t c . t o exc lude f l i e s from dung and t o r a i s e f e r m e n t a t i o n t empera tu res t o l e v e l s l e t h a l f o r f l y l a r v a e , e t c . , i . e . above 50°C, ( F i g s . 9-11). Manure may be s tocked on a c o n c r e t e f l o o r surrounded by g u t t e r s wi th water f o r t r a p p i n g m i g r a t i n g l a r v a e o r s p r e a d and d r i e d .

( d ) Manure s l u r r y c o n t a i n e r s . F l y b reed ing o c c u r s i n " i s l ands ' " and r e s i d u e s of dung. The s o l i d p a r t s of dung should be e l i m i n a t e d ,

( i i ) Human excrement ( s e e Wagner & Lanoix, 1958) .

( a ) L a t r i n e p i t s , b u c k e t s , e t c . , open t o f l y i n f e s t a t i o n . Non-fly b reed ing p r i v i e s should be i n s t a l l e d (Fig . 1 2 ) (e.g. aqua-pr iv ies w i t h a s l a b w i t h a wa te r s e a l p r e v e n t i n g a c c e s s of f l i e s t o t h e excrement ; f ly-proofed l a t r i n e houses ) w i t h a vent-pipe and f i x - n e t . The c o v e r s o r l i d s of p i t s , bucke t s , e t c . , should be f ly -p roofed , o r water c l o s e t s i n s t a l l e d , b u t t h e s e r e q u i r e s e p t i c t anks o r a proper sewage system.

( b ) L a t r i n e dumps (mainly i n r u r a l a r e a s ) . The e x c r e t a may be t r e a t e d a s dung ( s e e ( i ) above) .

( c ) I n d i s c r i m i n a t e d e f e c a t i o n ( o u t s i d e l a t r i n e s , t o i l e c s , e t c l . T h i s i s a source of Musca sorbens . It may be e l i m i n a t e d by t h e p r o v i s i o n of proper P a i r i n e s , e d u c a t i o n an$ change of h a b i t s , o r t h e s y s t e m a t i c removal of exposed f a e c e s i f i p r o b l e ~ a r e a s .

( i i i ) Garbage, d i s p o s a l and s t o r a g e a t source

The fo l lowing d i f f e r e n t s i t u a t i o n s should be cons ide red :

- Disposa l and s t o r a g e i n s i d e and o u t s i d e houses . Garbage containers ( b i n s , boxes , b a s k e t s , c a n s , bags , e t c . ) ;

- Hote l s , r e s t a u r a n t s , c o f f e e shops , e t c ;

- I n s t i t u t i o n s : s c h o o l s , h o s p i t a l s , e t c ;

- Food shops, e s p e c i a l l y where meat , f i s h , f r u t t and v e g e t a b l e s a r e s o l d ;

- Food marke t s , bo th wholesale and r e t a i l ; meat, f i s h , v e g e t a b l e s , f r u i t ;

- Slaugh te rhouses ;

- Food i n d u s t r i e s : food packing, p roduc t s o f Erui t , v e g e t a b l e s , e t c . ;

- Rendering p l a n t s where dead an imals and s l a u g h t e r o f f a l a r e p rocessed ;

- S t r e e t s and roads , r o a d s i d e s , e t c . , e.g. r e s t i n g and g;t t t terir \g p l a c e s ;

Fig. 9. Dung heac covered w i t h heavy plastic sheet (Photograph by J. Ke id ing . )

F ig . 1C). Temperat:lres i n a drlng h e a p before ( t o p ) and a f t e r cover ing with tarpa

w H O / V B C / ~ ~ . 937 page 23

i , ih i !b i~r , i arcw

A ~ c , i t i,r loose so,/ irrro ,$/rich /ttr,,ne surrtt'rirr~cs trriplofr L h - orrn so~~re~ir r res ruu hot 10 bc r~ihizbileti B - g r i ~ u ~ ! ~ l ~ # , r f i o c ~ C - soii

F i g . 11. C m s s - s e c t i o n o f haycock-shaped manure compost p i l e showing a r e a i n h a b i t e d by house- f l y l a r v a e on t h e 6 t h day ( a f t e r G o t a a s , 1956).

F ig . 12. Suppor t ed p i t l a t r i n e w i t h v e n t i l a t i o n w i t h v e n t p i p e p r o v i d e d w i t h f l y s c r e e n t o p r e v e n t f l y b r e e d i n g (Chrysomya s p e c i e s o r Musca d o m e s t i c a ) (Erom Feachem & C a i r n c r o s s , 1978) .

W H O / V B C / ~ ~ . 937 page 24

- Camping s i t e s ; and

- Sea s h o r e s , p a r t i c u l a r l y where g a r b - ~ g e i s dumped i n t h e sea.

3easure.s t o improve ga rbage d i s p o s a l and s t o r a g e a t source t;i $ reven t f l y breeding a r e i n p r i n c i p l e common t o t h e s e d i f f e r e n t s i t u a t i o n s : ( i ) p r o v i s i o n , c l e a n i n g and maintenance of f ly-proof garbage c o n t a i n e r s of s u f f i c i e n t zagaehcj {b i r i s , boxes, cane, bags o r b u l k s t o r a g e c o n t a i n e r s , e t c . ) ; ( ~ i ) hand l iqg garbage t o ? v o i d s p i l l a g e , exposure t o f l i e s , e t c . , e.g. , by wrapping; c l e a t l l i i ~ e s s and order t h e premises; ( i i i ) adequa te c o l l e c t i o n r e f v i c e ( s e e below); ( i v ) l o c a l garbage p i t s wi th t ight covers o r s m a l l i n c i n e r a t o r s f o r c e r t a i n premises .

Garbage c o l l e c t i o n and t r a n s p o r t

Problems i n r e l a t i o n t o f l y i n f e s t a t i o n :

( a ) Frequency of c o l l e c t i o n : i n a warm c l i m a t e c o l l e c t i o n twice ii: week i s n o t enough to prevent f l y p roduc t ion from garbage c o n t a i n e r s , a s pupa t ing l a r v a e may emigrate* ( F l i n t h o f f , 1984) . The r e s i d u e of wet garbage s l u d g e In cl;ncainers may support con t inuous b reed ing .

( b ) P o i n t s of c o l l e c t i o n : o n - s i t e , a t t h e c u r b , c e n t r a l c o l l e c t i o n p o i n t s , t ransfer s t a t i o n s , e t c .

( c ) S p i l l a g e of garbage from c o l l e c t i n g t r u c k s .

( d ) Transpor t of f l i e s by c o l l e c t i n g t r u c k s .

( e ) F l i e s may breed i n r es id i t e s o f s ludge and g r e a s e i n t h e t r t ~ c k s .

( v ) Garbage, t r e a t m e n t and f i n a l d i s p o s a l ( s e e WHO, 1971) .

( a ) Dumping. Refuse dumps g i v e s e r i o u s f l y problems, due t o f l y breeding and a t t r a c t i o n . The d i s t a n c e from s e t t l e m e n t s i s impor tan t . Dumping a t s e a t i t t e r s the s h o r e l i n e .

( b ) S a n i t a r y l a n d f i l l s . A compact cover of a t l e a s t 1 5 cm of s o i l i s needed t o prevent f l y emergence ( F i g . 13) .

( c ) Composting. Heavy f l y b r e e d i n g may occur i n t h e depot of garbage b e f o r e composting and d u r i n g f e r m e n t a t i o n , but u s u a l l y n o t i n t h e f i n i s h e d compost. Frequent turning d u r i n g composting w i l l k i l l f l y s t a g e s .

( d ) I n c i n e r a t i o n . F ly b reed ing may occur i n t h e depot of garbage.

( v i ) Sewage and waste water

F l y b reed ing , f l y a t t r a c t i o n , a dangerous source of d i s e a s e germs.

( a ) Accumulation of s ludge and s o l i d o r g a n i c waste i n open sewage d r a i n s , cesspools, seepage p i t s , e t c . Sewage d r a i n s , e t c . should be covered.

( b ) Sewage beds and sewage farms. Dumps of sewage s l u d g e should be covered with dry s o i l , sewage beds f l u s h e d , s o i l we t ted w i t h waste water . D i r e c t waste water o u t l e t s a"d c o n c e n t r a t e d ,hrowing of waste wa te r on t h e s o i l s u r f a c e should be avoided.

WHO/VBC/86.937 page 2 5

In relatively level areas

On a slope

lllYAlllR6 YlXOI rfi

hy ON SLOPE

/ / C O M P I I T E O RfFMSf COVER MAfERlAL

Fig . 13. S a n i t a r y l a n d f i l l .

v i i ) S o i l mixed o r impregna ted w i t h o r g a n i c m a t t e r

( a ) The l i t t e r i n g o f s o i l a r o u n d h o u s e s , s t a b l e s , c a t t l e E e e d l o t s , s h o p s , m a r k e t s , s l a u g h t e r h o u s e s , p l a c e s where f i s h a r e l a n d e d , e t c . , w i t h g a r b a g e o r manure, o r i m p r e g n a t e d w i t h b lood o r l e a k a g e frorn g a r b a g e , manure, e t c . , s h o u l d be avo ided . I n d r y a r e a s c o n t a m i n a t e d a r e a s s h o u l d n o t be w a t e r e d ,

( b ) I n rnanilring F i e l d s , g a r d e n s , e tc . , w i t h e x c r e m e n t , dung, g a r b a g e and o t h e r o r g a n i c m a t e r i a l s unde r s u i t a b l e m o i s t u r e c o n d i t i o n s , heavy a p p l i c a t i o n s i n lumps shou ld be a v o i d e d and cornposted manure u sed .

J . 2 E l i m i n a t i o n o f s o u r c e s t h a t a t t r a c t f l i e s from o t h e r a r e a s

The i m p o r t a n t s o u r c e s of o d o u r s a t t r a c t i n g f l i e s and s t r o n g l y i f i c r ea sdng l o c a l f l y d e n s i t y r e t o a g r e a t e x t e n t t h e same a s t h e p o t e n t i a l b r e e d i n g s o u r c e s i n w a s t e men t ioned above unde r -1.1). Such s o u r c e s may w e l l be v e r y a t t r a c t i v e t o f l i e s due tl3 t h e s m e l l , even i f f l y r e e d i l g c a n n o t t a k e p l a c e :

- a n i m a l man i r e ( b o t h F re sh and d e c a y i n g ) i n s t a b l e s , pens , dung h e a p s , compost h e a p s , e t c :

- human exc remen t : l a t r i n e s , l a t r i n e dumps, et : . ;

WHO/VBC/86 .937 page 26

- g a r b a g e , e s p e c i a l l y i f c o n t a i n i n g p r i , t e i n ( s l a u g h t e r and f i s h o f f a l ) , and dllowed t o decay f o r a f e w d a y s ; d e c a y i n g f r u i t i s a l s o v e r y a t t r a c t i v e ;

- campos t ing p l a n t s f o r g a r b a g e ; and

- sewage and w a s t e w a t e r .

C l e a n l i i ~ e s s and f r e q u e n t g a r b a g e c o l l e c t i o n a r e most i m p o r t a n t .

O the r s o u r c e s o f a t t r a c t i o n are :

- f r e s h o r d r i e d f r u i t t h a t g i v e o f f s w e e t , a r o m a t i c o d o u r s ;

- f i sh -mea l , blood-and-bone m e a l , some o i l c a k e s , and o t h e r odo rous i n d u s t r i a l o rgan ic p r o d u c t s ;

- m o l a s s e s and m a l t from b r e w e r i e s , and o t h e r swee t and s o u r s m e l l i n g m a t e r i a l s i n food i n d u s t r i e s ( m i l k and c h e e s e , e t c . ) ;

- o d o u r s f rom p r e p a r a t i o n of food i n r e s t a u r a n t s , k i t c h e n s , food s t a l l s , e t c . a n d ;

- o d o u r s from t h e food i n d u s t r y , e .g . p r o c e s s i n g mangoes and o t h e r f r u i t .

V.1.3 E x c l u s i o n o f f l i e s from c o n t a c t w i t h m a t e r i a l s c o n t a i n i n g p a t h o g e n i c germs ( s e e a l s o V . 1 a b o v e ) .

( i ) Animal e x c r e m e n t , e s p e c i a l l y a s r e g a r d s e g g s and c y s t s o f p a r a s i t i c worms.

( i i ) Human exc remen t and o t h e r e x c r e t a from i n f e c t e d p e o p l e .

( i i i ) Garbage. S p e c i a l p r e c a u t i o n s a r e r e q u i r e d i n t h e s t o r a g e and d i s p o s a l o f r e f u s e from h o s p i t a l s and c l i n i c s .

( i v ) D i r t y food u t e n s i l s * a f t e r s e r v i n g o f m e a l s , f l y a t t r a c t i o n may be avo ided by s c r e e n i n g * o f r e s t a u r a n t s , k i t c h e n s , e t c .

( v ) Sewage.

( v i ) I n f e c t e d e y e s , s o r e s , wounds and s k i n of humans, f l y a t t r a c t i o n may be avo ided by s c r e e n i n g o f h o s p i t a l s , c l i n i c s , e t c .

V.L.4 P r o t e c t i o n o f food , u t e n s i l s and man from c a n t a c t w i t h f l i e s (non-chemical methods)

P r o t e c t i o n of food and food u t e n s i l s

(j) A t t h e p r e p a r a t i o n and q e r v i n g o f m e a l s , and s t o r a g e b e f o r e and a f t e r mea l s i n homes and r e s t a u r a n t s , e t c . , and Z n . ; t i t u t i o n s , k i t c h e n s , d i n i n g rooms, e t c . , food s t o r e s , l a r d e r s , p a n t r i e s .

( i i ) I n shops and m a r k e t s ( a e a t , f i s h , f r ) : i t , v t i q e t ~ ' n l ~ s , sweets, a i l k ?rid o t h e r beve rages , e t c . f .

( i i i ) A t s l a u g h t e r h a ,.A.;.

( i v ) I11 o t h e r Food i n d u s t r i e s : d a i r i e s , mea t , f i s h , f r u i t , veqetabLe-packi17g, s w e e t s , e t c .

( v ) I n f r u i t n r c h a r d s and v e g e t a b l e g i r d e q s .

WHO/VBC/86.937 page 27

P r o t e c t i o n of m a t e r i a l s , i n s t r u m e n t s , e t c . , used f o r medical t r e a t m e n t s o r pe r sona l hygiene

( i ) I n s t i t u t i o n s : h o s p i t a l s , c l i n i c s , m a t e r n i t y wards, s a n a t o r i a , i n f a n t homes, s c h o o l s , e t c .

( i i j P r i v a t e d w e l l i n g s (bathrooms, bedrooms). S p e c i a l needs f o r i n f a n t s , s i c k and handicapped people must be recogn ized .

P r o t e c t i o n o f man

I n i n s t i t u t i o n s and homes, b u i l d i n g s and rooms f o r work, r e c r e a t i o n and r e s t and i n t h e s t r e e t s and o t h e r ou tdoor a r e a s where peop le g a t h e r .

Apart from i n s e c t i c i d e f l y c o n t r o l ( s e e below), t h e f o l l o w i n g measures a g a i n s t f l y c o n t a c t may be mentioned:

- t h e p r e v e n t i o n of f l y a c c e s s by p l a c i n g food and u t e n s i l s , e t c . , i n f ly-proof c o n t a i n e r s , cupboards , wrapping m a t e r i a l , e t c . , t h e s c r e e n i n g o f windows, v e n t i l a t i o n openings and doors , t h e u s e o f f l y n e t s t o p r o t e c t b a b i e s , peop le i n beds , e t c . ; t h e u s e of a n t i f l y c u r t a i n s ( s t r i p s of beads , p l a s t i c s t r i p s , e t c . ) i n doorways (Morgan, e t a 1 1972); by e l e c t r i c f a n s t o c r e a t e a n "air c u r t a i n " (Mathis , e t a l e , 19701, * ' a c r o s s doorways ( a i r v e l o c i t y 8 m/sec o r more), t h e d e v i a t i o n o f f l i e s t o o t h e r food s o u r c e s , and t h e use of r e p e l l e n t s .

Non-chemical c o n t r o l ( s e e S e c t i o n V . 4 ) )

(I) Catching o f f l i e s i n t r a p s ( w i t h b a i t s o r l i g h t a s a t t r a c t a n t ) o r on s t i c k y f l y - - ; e r ( n o t v e r y e f f e c t i v e ) .

( i i ) K i l l i n g f l i e s w i t h e l e c t r i c g r i d s ( e l e c t r o c u t o r s * ) combined w i t h a t t r a c t a n t s .

( i i i ) K i l l i n g f l i e s wi th f l y s w a t t e r s .

Sc reen ing of b u i l d i n g s is t h e most impor tan t method of p r o t e c t i o n a g a i n s t f l y i n v a s i o n , but reduced v e n t i l a t i o n and 1 I g h t c a n c a u s e inconvenience. To keep h o u s e - f l i e s o u t , a 1 0 mesh s c r e e n is s u f f i c i e n t , whereas a n 18 mesh i s r e q u i r e d f o r mosqui tos . Metal s c r e e n s may cor rode and p l a s t i c - n y l o n s c r e e n s may be t o r n , s o p r o t e c t i o n by s t r o n g , c o a r s e hardware c l o t h may be necessa ry i n exposed p laces . Sc reen d o o r s must be s e l f - c l o s i n g . Even s o , f l i e s may be brought i n w i t h people pass ing . A n t i f l y c u r t a i n s may be reasonab ly e f f e c t i v e , bu t more in fo rmat ion is needed. "Air c u r t a i n s " a r e e f f e c t i v e and conven ien t where t h e y can be i n s t a l l e d .

Educat ion and p u b l i c c o o p e r a t i o n i n env i ronmenta l s a n i t a t i o n programmes

F l y c o n t r o l by env i ronmenta l s a n i t a t i o n must be done by a c t i v e c o o p e r a t i o n between t h e i n h a b i t a n t s of t h e comrormnity and t h o s e o r g a n i z i n g r a t i o n a l was te c o l l e c t i o n and d i s p o s a l . It i s a b s o l u t e l y fundamental t h a t t h e i n h a b i t a n t s unders tand t h e problems and do t h e i r p a r t by keeping homes, shops, s t a b l e s , e t c . , and t h e i r su r round ings c l e a n , by c o r r e c t d i s p o s a l and s t o r a g e of wastes and excrement on s i t e t o p reven t Ely b reed ing and c o n t a c t , by p r o t e c t i n g food, u t e n s i l s , e t c . , a g a i n s t c o n t a c t w i t h f l i e s , and by a s s i s t i n g i n any s a n i t a r y measures ~ r g a n i z e d by t h e community.

S a n i t a r y e d u c a t i o n and i n f o r m a t i o n o f t h e p u b l i c i s fundamental:

WHOIVBCf86.937 page 2 8

- e d u c a t i o n o f c h i l d r e 1 1 i n s c h o o l s ( p r e p a r e d by c o u r s e s f o r t e a c h e r s ) ;

- e d u c a t i o n and i n f o r m a t i o n a f t h e g e n e r a l p u b l i c t h r o u g h m e e t i n g s w i t h d e m o n s t r a t i o n s a1 a u d i o v i s u a l m a t e r i a l ( raovies , p i c t u r e s ) , by s e a s o n a l p o s t e r s , d i s t r i b u t i o n o f p r i n t f i l l u s t r a t e d pamph le t s , r a d i o and t e l t - r i s o n programmes, t h e l o c a l i?t.wapapers, e t c . ; and

- i n f o r m a t i o n o f p c i l k t i c i a n s , a d m i n i s t r a t o r s a n d o t h e r l e a d i n g p e r s o a s conce r i l i ng tt i m p o r t a n c e o f e n v i r o n m e n t a l s a n i t a t i o n . ,

The community must have s a n i t a r y r e g u l a t i o n s and o r d i n a n c e s , and meqns f o r e n f o r c i n g the ( s a n i t a r y i n s p e c t o r s , p e n a l t y f a r b r e a k i n g t h e r u l e s , e t c . ) .

V , 2 . I n s e c t i c i d a l c o n t r o l P-

There a r e s i x main t y p e s o f a p p l i c a t i o n f o r c h e m i c a l f l y c o n t r o l , one a g a i n s t preadu: s t a g e s ( 1 ) t r e a t i n g b r e e d i n g p l a c e s w i t h l a r v i c i d e s , and f i v e a g a i n s t a d u l t s : ( 2 ) a p p l y i t r e s i d u a l t r e a t m e n t s , m a i n l y s p r a y s , t o r e s t i n g - s i t e s and o t h e r s u r f a c e s f r e q u e n t e d by f l i e f ( 3 ) i n t r o d u c i n g t o x i c r e s t i n g - s i t e s , m a i n l y impregna ted s t r i p s , c o r d s , e t c . , ( 4 ) t o x i c b a i t s ( 5 ) s p a c e s p r a y s and d i r e c t s p r a y i n g o f f l y a g g r e g a t i o n s i n d o o r s and o u t d o o r s , and ( f f u m i g a t i o n (WHO, 1984) .

V. 2.1 L a r v i c i d e s *

i n t h e o r y , t r e a t m e n t o f b r e e d i n g p l a c e s w i t h l a r v i c i d e s would a p p e a r t o b e t h e logic : method f o r c o n t r o l l i n g f l y p o p u l a t i o n s , b u t i n p r a c t i c e t h e r e a r e s e v e r a l drawbacks . The mos i m p o r t a n t is t h a t t h e b r e e d i n g media a r e a c c u m u l a t i n g and c h a n g i n g c o n t i n u o u s l y and t h e r e f o l f r e q u e n t t r e a t m e n t s , e .g. once o r t w i c e a week, a r e r e q u i r e d . F u r t h e r , t h e p e n e t r a t i o n ar d i s t r i b u t i o n o f t h e l a r v i c i d e i n t h e medium i s o f t e n a problem; most l a r v i c i d e s a l s o k i l n a t u r a l enemies o f f l y s t a g e s and may d i s r u p t t h e b i o l o g i c a l r e g u l a t i o n ; and f i n a l l y u se c l a r v i c i d e s may f a v o u r development o f r e s i s t a n c e * .

Most commonly, l a r v i c i d e s a r e a p p l i e d a s e m u l s i o n s , s u s p e n s i o n s o r s o l u t i o n s w i t h s p r a y e r g i v i n g a c o a r s e s p r a y ( o r a w a t e r i n g c a n ) a t a r a t e s u f f i c i e n t t o w e t t h e uppe r 10- 1 5 c m o f t h e medium t h o r o u g h l y , i . e . 0.5-5 l i t r e s / m 2 . A p p l i c a t i o n s o f d u s t o r g r a n u l a t e f o r m u l a t i o n s may a l s o be u sed .

O r i g i n a l l y s e v e r a l c h l o r i n a t e d h y d r o c a r b o n s , e.g. HCH and d i e l d r i n , we re u s e d , b u t a r e nc r u l e d o u t due t o r e s i s t a n c e . Many o rganophosphorus (OP) compounds a r e e f f e c t i v e s l a r v i c i d e s p r o v i d e d r e s i s t a n c e t o t h e p a r t i c u l a r OP i s n o t a problem ( M i l l e r , 1970) . Tt d o s a g e s recommended below a p p l y t o non- re s i s t a n t f Ly p o p u l a t i o n s . D iaz inon (0.3-1.0 g/m2) i one of t h e b e s t , when b o t h a n i n i t i a l and a r e s i d u a l e f f e c t a r e c o n s i d e r e d . D i c h l o r v o s i s l i g h t l y more e f f e c t i v e f o r a n immedia te k i l l and h a s a f u m i g a n t e f f e c t , b u t p r a c t i c a l l y r r e s i d u a l e f f e c t e x c e p t i n s l o w - r e l e a s e p l a s t i c f o r m u l a t i o n s . O the r OPs recommended a l a r v i c i d e s , b u t u s u a l l y r e q u i r i n g h i g h e r d o s a g e s (e .g . 1-2 g/m2) a r e t r i c h l o r f o n , d ime thoa t f f e n c h l o r p h o s , coumaphos, t e t r a c h l o r v i n p i ~ o s , hromo.[~hos, f e n i t r o t h i o n and Fert thion. I f C compourlds a r e u sed a s l a r v i c i d e s r e s i s t a n c e w i l l o f t e n be a problem. S e v e r a l o f t h e n e w p h o t o s t a h l e p y r e t h r o i d s ( s e e T a b l e 2 ) a r e e f f e c t i v e l a : -v t c ide t a t d o s a g e s l ower t h a n thoc recommended f o r OPs. However, due t o t h e r e s i s t a n c e r i s k , p y r e t h r o i d s s h o u l d be r e s e r v e d f c c o n t r o l of a d u l t f l i e s , a s t h e r e a r e o t h e r e f f e c t i v e l a r v i c i d e s a v a i l a b l e .

TWO i n s e c t development i n h i b i t o r s * , d i f l u h e n z u r o n and cy romaz ine h3ve S ~ O W ~ I an e x c e l l e n e f f e c t i n f i e l d e x p e r i m e n t s and p r a c t i c a l u se i n r e c e n t y e a r s , Dif lubenzarorr (=DimilinSF 6040 o r TH 6040) i s e f f e c t i v e a t a c n n . c e n t r a t i o n O F 1-2 ppm ( l g / n 3 ) i n manure and i recommended f o r s p r a y i n g o r j i a t e r i a g t h e s u r f a c e o f mant l r i . : tcci tmii lat tons a t r a t e o f 1 a c t i v e i n g r e d i e n t ( a . i . ) p e r m 2 , a t 2-3 weeks V i n t e r v a l . D i f Zuberizuroi~ i n h i h i , t s t h e norm3 f o r m a t i o n of c h i t i r t and thris h a s a rno~!t? of a c t i o n t h a t i s v e r y d i i f e r e i ~ t from t h e contrentiona t n s e c t i c<.'es (,i. , g . >rgn:l:-p':-s;'?,,r::s -?rh?- ! t i e ?::,l ;;'ret!:r:;?.s t r : ~o_ ! f ? r f1;i ~ . ' ~ t r ' : ?~ .

Cyromazine ( = Neporex f o r t r e a t i n e n t of manitre, o r Larvndex for mix ing i n t o t h e feed 0 p o u l t r y o r p i g s ) i s a t r i a z i n e compound, q u i t e d i f f e r e n t c h e m i c a l l y from d i f l t t h e n z u r o n and th

WHO/VBC/86.937 page 29

c o n v e n t i o n a l i n s e c t i c i d e s . It i s v e r y e f f e c t i v e a s a l a r v i c i d e f o r f l y c o n t r o l i n manure, p r e v e n t i n g t h e l a r v a e from deve lop ing i n t o pupae and a d u l t s . I ts mode of a c t i o n is no t w e l l unders tood . It is e f f e c t i v e a t a cor icen t ra t ion of 0.5-1.0 ppm (g/m3) i n manure and recommended a t a r a t e of O+5-l.Og of a . i . per m 2 , a p p l i e d a s a 2 % g r a n u l a t e o r sprayed o r wa te red on the s u r f a c e of t h e manure a t a c o n c e n t r a t i o n of 0.5-1.0% i n wa te r (Mulla & Axelrod, i 9 8 3 ) .

Dif lubenzuron and cyromazine do no t a d v e r s e l y a f f e c t many of t h e non- ta rge t fauna i n t h e manure, i n c l u d i n g many p r e d a t o r s * and p a r a s i t e s which may be u s e f u l a s b i o l o g i c a l c o n t r o l * a g e n t s of the f l y popu la t ion . These two i n s e c t development i n h i b i t o r s a r e of low t o x i c i t y t o v e r t e b r a t e s and a r e s u i t a b l e and e f f e c t i v e when mixed i n t o the f e e d of p o u l t r y o r p i g s t o k i l l t h e l a r v a e i n the excrements. Dif lubenzuron i s e f f e c t i v e a t c o n c e n t r a t i o n s of 6-25 ppm (g/m3) i n p o u l t r y and p i g feed and cyromazine a t 1.5-5 ppm.

A s f a r a s f l y c o n t r o l i s concerned t h i s feed-through method has t h e advantage t h a t i t is e a s y t o treat a l l t h e manure w i t h t h e c o r r e c t dosage, b u t i t has t h e d i s a d v a n t a g e t h a t a s t r o n g s e l e c t i o n p r e s s u r e is a p p l i e d t o t h e f l y p o p u l a t i o n and t h u s g r e a t l y i n c r e a s i n g t h e r i s k of development of r e s i s r a n c e t o t h e l a r v i c i d e . I n a d d i t i o n , i n most c o u n t r i e s t h e r e i s a growing o b j e c t i o n t o us ing i n s e c t i c i d e s a s f e e d a d d i t i v e s , a s t h e r e may be problems of r e s i d u e s i n eggs and meat. The OP-compound t e t r a c h l o r v i n p h o s is a l s o s u i t a b l e f o r feed- through a p p l i c a t i o n where r e s i s t a n c e is n o t a problem.

A g r e a t number of o t h e r compounds t h a t a r e no t conventional. i n s e c t i c i d e s a r e ( o r have been) used f o r c o n t r o l o f house-f ly l a r v a e l o c a l l y , e .g . ca lc ium a r s e n a t e , pheno th iaz ine , borax, c h l o r i d e of l i m e , ca lc ium cyanamide mixed w i t h superphospha te , h e l l e b o r e o r o r h e r p l a n t a L k a l o i d s , v a r i o u s c r u d e o i l s , c r e o l i n , e t c . (Ascher & Levinson, 1953; Sampson, 1956). Buwever, most of t h e s e o l d l a r v i c i d e s r e q u i r e high dosages and may make manure u n f i t f o r u s e a s a f e r t i l i z e r .

V-2.2 Res idua l t r ea tment* of r e s t i n g - s i t e s

S i n c e the appearance of DDT d u r i n g t h e Second World War, s p r a y i n g house-f ly r e s t i n g - s i t e s w i t h a r e s i d u a l i n s e c t i c i d e has been t h e main method of chemical f l y c o n t r o l i n many a r e a s . DOT was a "miracle" i n s e c t i c i d e , one c o r r e c t l y a p p l i e d t r e a t m e n t c o n t r o l f i n g Ely p o p u l a t i o n s f o r months, bu t t!ie development o f r e s i s t a n c e soon r u l e d o u t t h e u s e of DDT and o t h e r c h l o r i n a t e d hydrocarbons i n most p l a c e s . Various OP compounds and p y r e t h r o i d s a r e now used and ?he r e s i d u a l e f f e c t Is tist ially a m a t t e r of two t o s i x weeks and r a r e l y a s long a s two t o f o u r months.

The pe r iod of e f f e c t a f t e r a s p r a y t r e a t m e n t f o r a g i v e n compound (and dosage) depends on s e v e r a l f a c t o r s , e.g. fo rmula t ion ( w a t e r d i s p e r s i b l e powders may he b e t t e r than e m u l s i o n s ) , t y p e of sprayed s u r f a c e ( reduced e f f e c t on absorban t o r a l k a l i n e s u r f a c e s ) , t empera tu re (decreased r e s i d u a l e f f e c t a t h i g h t e m p e r a t u r e s ) , humidi ty and mois tu re , exposure t o s u n l i g h t , and l a s t but no t l e a s t t h e l e v e l of r e s i s t a n c e i n t h e f l y p o p u l a t i o n o r t h e i r p o t e n t i a l f o r deve lop ing i t .

The pe r iod of f l y c o n t r o l , i . e . a s a t i s f a c t o r y r e d u c t i o n of f l y i n c i d e n c e i n t h e l c 3 c a l i t y , depends on t h e r a t e of i n f l u x of new f l i e s ( l o c a l b reed ing p l u s immigration*) i n r e l a t i o n t o the r a t e of k i l l , which agai t t depends on t h e p r o p o r t f o n o f t h e f l i e s r e s t i n g on t h e t r e a t e d s u r f a c e s aitd t h e l e n g t h of t ime they c t a y .

It is t h e r e f o r e e s s e n t i a l t o i n v e s t i g a t e and i d e n t i f y t h e a r e a s & e r e t h e f l i e s spe r~d most c i f t h e i r t ime, p a r t i c t i l a r l y t h e n i g h t r e s t i n g - s i t e s , p r e v i o u s l y d e s c r i b e d , and t o t r e a t t h e s e . l ' i is may permit s e l e c t i v e t r e a t m e n t s , where :)nly p a r t s of t h e s p r a y a b l e s u r f ~ c e s -ire .;prayed. Thus, i n a q i a a l sheds i t a a y be s u f f i c i e n t t o t r e a t stanchions, p- i r t s of p a r t i t i o n s , wiodows, po.;ts, g i r d e r s , and the c e i l i n g a r e a above the an imals , e.g. 30% of thy .ijrr~i-iy tbLe area

7 \ (F ig . 1 ) .

It i s g e n e r a l l y agreed t h a t insecticidal Cly c o n t r o l should s t3t - t e ; i r ly i n the f l y seaso:?, s!le"rl f l y p r c ~ d u c t i o ~ l i s s t i l l Low, bu t same recl21nmend s t a r t i n g wlth trci; i t-?rnti o r h e r t i t a n

WHO/VBC/86.937 page 30

r e s i d u a l s p r 3 y s a n d t o s a v e t h e s e f o r t h e p r , lper f l y sedso.1. As a r u l e t h e r i s k ctf d e v e l o p i q g r e s i s t a n c e i s g r c b - l t e r wiren r e s i d u a l 4 p r a y s drs u s e d tftar: w i t h o t h e r t r e d t i r e n t s a g a i n s t a d u l t f l i e s .

R e s i d t r a l s g r a y s lnay he a p p l i e d by l id~~d-oper i t t : ed o r p o w e r - u p e r a t d s p r a y e i - s a t low p r e s s u r e ( t o a l i o i d d r i f t ) ai,d a t t h e r a t e \lf 4-8 L i t r e s per- iO i3 m2 s p r a y e d s i i r f a c e . T!?e i i : s e c t i c i d e s u s e d 15 r e s i d u a l sprlps f o r - f l y c t ~ n t r c t t a r e shi3wn E I I 'T:-tt;!e 2 .

Ttir i .hr,ice ; t i i :~sec:i i : ide dei>e: lds oil .:o:;t, tnxi.1- E t d ~ 3 ~ i l ~ j , 1c)cdl ~ ~ n d i i l i o i i s ( i l i m a t e , :;pr-xye,j s a r f , a c e s ; , e t c . ) ai1.3 F l y r e s i s t a t i c e . T i ~ ~ r e f r i r e , i r . i s d i f f i c u l t t c , r a n k t he in . ;e i-c;cicics . p:)r exninple, .iinong t h e OP corni?i?uilds diilit?tko;tt? is ;r~t-,st;3:!c?~!lg i l l some a r e a s , g i v i n g e x c e l l e r ~ t c o n t r 3 1 f o r two o r more mriilri?:j, i n o t k i r r s i t is iicir S O gc>od- MaLatt i ion bias ?i,wer t i t x i c i t y t o iliir~lal h o t : s e - - f l i e s t h a n mast o f t i i e o t h e r s iind r n a i ~ t i i i c ~ r ~ r e s i s u n c e i s very widespr tzad . I n .;,>me c o r t n t r i e s t h e a d d i t i o n o f stlg:ir t o t h e s p r a y , e .g . a t t i l e r a t e o f 1-2 .5 g / m 2 1 i s recommended t o i n c r e a s e t h e e f f e c t and s t a b i l i t y o f t h e i n s e c t i c i d e o n t h e s u r f a c e , bt t t t h i s may b e u n a c c e p t a b l e i n roams w i t h a h i g h h u m i d i t y . F o r t r i c h l o r f o n , w h i c h h a s an i m p o r t a n t s t o m a c h - p o i s o n e f f e c t , s u g a r i s r e g u l a r l y u s e d i n t h e f o r m u l a t i o n s . T r i c h l o r f o n has p l a y e d a d o m i n a n t r o l e i n i n s e c t i c i d a l f l y c o n t r o l . o f t h e USSR and o t h e r c o u n t r i e s i n e a s t e r n E u r o p e . N a l e d i s recommended a s a r e s i d u a l s p r a y i n t h e USA, b u t i t s r e s i d u a l e f f e c t i s r a t h e r s h o r t . F o r m o s t o f t h e OPs t h e r e a r e r e s t r i c t i o n s i n some c o u n t r i e s f o r t h e i r u s e f n mi lk- rooms, f o o d - p r o c e s s i n g p l a n t s o r o t h e r p l a c e s w h e r e f o o d i s e x p o s e d , a n d s e v e r a l a r e a l s o r e s t r i c t e d a s r e g a r d s e x p o s u r e t o c h i c k e n s , d a i r y cows a n d o t h e r a n i m a l s p r e s e n t d u r i n g t h e s p r a y i n g .

S e v e r a l p h o t o s t a b l e p y r e t h r o i d s a r e v e r y e f f e c t i v e a s r e s i d u a l s p r a y s , w h e r e p y r e t h r o i d - r e s i s t a n c e is n o t a p r o b l e m ( F a r a o n e , e t a l . , 1 9 7 8 ) However, i n some a r e a s , e .g . p a r t s of E u r o p e a n d C a n a d a , h i g h r e s i s t a n c e t o p y r e t h r o i d s may d e v e L o p v e r y q u i c k l y a n d make a l l p y r e t h r o i d s ( i n c l u d i n g p y r e t h r u m ) i n e f f e c t i v e f o r f l y c o n t r o l b o t h a s r e s i d u a l s p r a y s and a s s p a c e s p r a y s , a e r o s o l s o r mists ( s e e s e c t i o n V . 3 ) . Tn a r z a s w i t h a h i e h p o t e n t i a l f o r d e v e l o p i n g p y r e t h r o i d - r e s i s t a n c e , p h o t o s t 3 b l e p y r e t h r o i d s a r e n o t recommended f o r u s e i n a n i m a l h o u s e s .

Some c a r b a m a t e s h a v e shown p r o m i s e i n c e r t a i n a r e a s , w h e r e c a r b a m a t e r e s i s t a n c e i s n o t a p r o b l e m , e .g . p r o p o x u r a n d b e n d i o i a r b mixed w i t h s u g a r . The d o s a g e rate is similar t o t h a t of t h e OPs m e n t i o n e d , b u t c a n d i d a t e c a r b a m a t e s a r e more t o x i c t o mammals a n d h a v e s o f a r n o t been i m p o r t a n t a s r e s i d u a l s p r a y s f o r f l y c o n t r o l .

I m p r e g n a t e d s t r i p s , c o r d s , e t c . -----p ---

The o b s e r v a t i o n s t h a t h o u s e - f l i e s s t r o n g 1 y p r e f e r e d g e s , s t r i n g s , w i r e s , e t c . , u n d e r t h e c e i l i r i g , e t c . , f o r n i g h t - r e s t i n g s t l g g e s t e d t h e u s e o f i m p r e g n a t e d t a p e s , s t r i p s , r o r d q , p a p e r , e t c . , f a r f l y c o n t r o l . The i d e a g o e s b a c k t o t h e 1 9 4 0 s when DDT and d i e l d r i n w e r e s t i l l e f f e c t i v e (Chow h Thevasagayam, 1 9 5 3 ) , b u t t h e maid d e v e l t p m e r l t t o o k p l a c e i r r t h e 19SOs, when OP cotnpoui-tds had t o b e i ~ s e d . O r i g i n a l l y t h e r h e a p bu+ g e r y t o x i c p a r a t h i o n was u s e d f o r r o m m r r r i a l l y imgi regna ted g a t l e r hand.: qr c , t t o r r cc i rdc , Thiair u s r i n d ~ i r i ~ s a n d m i l i t a r y p r - r n i s e ~ w e r e d e s c r i b e d by K i l p a t r i c k anti S r l ~ o o f ( 1 9 5 6 ) . L a t e r l e s s t s x i c i n s e r t i c i 2 e s have b e e n 5:sed w i t h good e f f e c t , e . g . che OPs d i . i z i n o n , rnrrne!, m a l a t i l ~ , ? n , f e n t h i o n , d l i n e t h o a t e and t r i c h l o r f o n , a n d t h e c a r b a m a t r s p r ~ p o x u r aild d 5 r n ~ t i l z n , s o t h a t t h e r e i s no l o n g e r nr:y p o i r ~ t i n u s i n g tFle diiilgerotls p a r a t h ion p r e p r a t i o n .

"or i m p r i - t p r ~ a t i o n w i t h t h e moderately t o x i c OPs, c;ol u t i ons o r ernill s ic~rs a t c o r ? c e ~ l t r a t i ~ n S of LO-25X, and e v e n a s l i t t l e a s I%, a r e u s e d , o f t e n m-lxrd w i t h some s u g a r arid a t t r a c t a n t p l u s g l u e r o i l f o r m a k i n g a d u r a b l e f i l m . , R e s i d e s g a u z e and c o r d s , f e l t e d c e i l i l 1 n s e and v i s c o s e o r foil I p l - i i ~ t i c bar lds arc3 a v a i l a b l e C - o m m e r c - i a l t ~ , and f u r I iomc-m~~de s t r i p s v a r i o u s itirids o f s t r o n g p a p e r inay be u s e d , a s w e l l a s :my , i v a i l a b i i . c o r d o r , : lo t l~ ,

/ 11 ~ i , t : s i Gicp+A L r i ~ ~ ~ r e g i ~ , ~ ~ e d ~ f . p V L ' ~ . , i a l i , ) i j l < i h t - L , + \ < + : p ~ t i n1i.o 4~ s..cjci : iL L L ~ L kigh

cctn~.c: i t rnf- i f in . ; t:f i n + c l c t i c i t l e s xay be t-episl le?:it ) r i r r i t a n t t o F 1 i p s . Tli l ts c* l o w e r c o n c e n t r a t i o n -nay s o m e t i m e s b e more e f f ec t ivc i : t h e a t t r a c t a n c e o r r e p e l l e n c y s h o u l d he t e s t e d u n d e r f i e l d c ~ i n d i t i o n s b e f o r e p r e p a r i n g o r buyizig i m p r e g r i a t e d m a t e r i a l s .

TABIX 2. ORGANOPHOSPHORUS (OP), CARBAMATE AND PYRETHROID INSECTICIDES USED FOR RESIDUAL TREATMENT IN FLY CONTROL

Inset t icide Common Dosage g/m2 Toxicity to Toxicity to trade name active susceptfble rats dermal

ingredient flies. Topical LD50 mg/kg LD50 ~ ~ g / f ly

Remarks

l OP compounds l azame thiphos Al facron Mainly sold as a sugar bait formulation.

bromophos d iazlnon dimethoate

Nexion Basudin Rogor ( Low level of resistance in most places. l

Eenchlorvos fenitrothion jcrdfenphos mnla tl~ion Resistance problems in most areas.

Rather short residual effect.

Nankor Sumithion Nuvanol

naled

pirimiplloslnethy 1 propetamphos trichlorfon

Dibrom

Low level o f resistance in most places. Mainly used as a sugar bait formulation.

Actellic Saf rotin Dipterex

Carhamates

bendiocarb propoxur

Ficam 0.1 - 0.2 0.3 Baygon 1 0.4

Animals must be removed. Cross resistance from use of OPs.

cypermethrin deltamethr in permethrin fenvalerate

Barricade Decis,K-othrin (several ) Sumicidin

In Canada and some parts of Europe resistance develops very quickly.

High 2 000 High High

WHO/VBC/86.937 page 32

The i -npregnated s t r i p s , band< , c o r d s , e t c . , a r e suspended under t h e c e i l i n g , v e r t i c a l p a r t s o r l o o p s b e i n g more a t t r a c t i v e t h a n h o r i z o n t a l o n e s , d a r k o r r e d b e t t e r t h a n l i g h t , Another method i s t o s t r e t c h t h e c o r d s o r bands o n f r ames t h a t a r e s t r a t e g i c a l l y p l a c e d and cap b e moved a c c o r d i n g t o need. Impregnated s t r i p s , c o r d s , e t c . , may be used i n a n i m a l sheds , p o u l t r y f a rms , m a r k e t s and s h o p s , r e s t a u r ~ t t t c ; a n 3 ally o t h e r f l y - i n f e s t e d room. The method is s t i l l a qerp u s e f u l way o f i l y c o n t r o l , hav lng t h e a d v a n t a g e of c h e a p n e s s , l o n g r e s i d u a l e f f e c t and l e s s chance o f development o f r e s i s t* i - i ce tiiarl r e s i d u a l s p r a y s . The r e d u c t i o n o f f l y 3pnsity may be r a t h e r s l o w i n i t i a l l y ; b u t w i t h r h r optimum l o c a t i o n t h e e f f e c t c a n be very s a t i s f a c t o r y , b o t h i n t e m p e r a t e and r r o p i c a l a r e a s a t t h e r a t e o f 1 m o r less o f band, e t c . , pe r s q u a r e m e t r e o f f l u o r a r e a . However, i t does n o t work i n rooms w i t h 3 L P d r a u g h t s tinder t h e c e i l i n g a s i n many modern v e n t i l a t e d rooms and s t a b l e s . The t e c l ~ n l q u e l e n d s i t s e l f well t o p r e v e n t i v e a p p l i c a t i o n s b e f o r e t h e s t a r t of t h e f l y s e a s o n .

The o l d method of t r e a t i n g bunches o f t w i g s w i t h f l y p o i s o n s and hang ing them i n f l y - i n f e s t e d s t a b l e s o r o t h e r l o c a l e s o r p l a c i n g them a t b r e e d i n g s i tes (dung h e a p s ) may be rtsef u l l y r e v i v e d u s i n g modern i n s e c t i c i d e s .

V.2.4 Toxic b a i t s

Use o f t o x i c b a i t s f o r f l y c o n t r o l i s v e r y o l d . Thus, b e f o r e t h e modern i n s e c t i c i d e s a p p e a r e d , s u g a r and w a t e r o r o t h e r f l y - a t t r a c t i n g l i q u i d s c o n t a i n i n g more o r less s t rong p o i s o n s such a s sodium a r s e n i t e were recommended. Milk o r swee t l i q u i d s w i t h 1-2% formaldehyde c a n s t i l l be recommended a s a f a i r l y e f f e c t i v e f l y k i l l e r .

The development o f OP compounds and ca rbamates w i t h a modera t e t o low t o x i c i t y t o mammals opened t h e way t o a v a r i e t y o f t o x i c f l y b a i t s which may be grouped a s f o l l o w s :

(L) Dry s c a t t e r b a i t s c o n t a i n i n g 0.1-2% of i n s e c t i c i d e i n a c a r r i e r which may be p l a in g r a n u l a r s u g a r o r s u g a r p l u s sand (Rosen & G r a t z , 1959) , ground c o r n c o b s o r o y s t e r s h e l l s , etc. , o f t e n w i t h some o t h e r a t t r a c t a n t added , e .g . t h e house - f ly pheromone musca lu re (Mathur, e t a l . , 1980) . P

The b a i t is b r o a d c a s t i n t h i n l a y e r s o f 60-250 g p e r l 0 0 m2 o n t o a v a i l a b l e d r y s u r f a c e s a t f l y a g g r e g a t i o n s , e .g . f l o o r s , pavements , e t c . , o r p l a c e d i n s p e c i a l b a i t s t a t i o n s , e.g. t r a y s o r c o n t a i n e r s o f m e t a l , wood, c a r d b o a r d , p l a s t i c , e t c .

( i i ) L i q u i d s p r i n k l e b a i t s c o n t a i n i n g i n s e c t i c i d e ( e . g . 0.1-0.2%) and s u g a r o r o the r swee ten ing a g e n t (e.g. 10%) i n w a t e r . The l i q u i d i s a p p l i e d by a s p r a y e r o r a s p r i n k l i n g can t o f l o o r s , e t c . , o r t o o t h e r s u i t a b l e h o r i z o n t a l o r v e r t i c a l s u r f a c e s , which a r e o r c a n be p l a c e d o u t of r e a c h o f a n i m a l s and c h i l d r e n ,

( i i i ) L iqu id b a i t d i s p e n s e r s c o n t a i n s i m i l a r f o r m u l a t i o n s t o t h e s p r i n k l e b a i t s and ~ o n s i s t of a c o n t a i n e r , i n v e r t e d j a r o r b o t t l e f e e d i n g a t r o u g h ( a s i n ch icken-wa te r ing d e v i c e s ) , a sponge o r a wick w i t h t h e l i q u i d ( K i l p a t r i c k , e t a l . , 1962) .

-P

V a r i e t i e s o f t h e l i q u i d b a i t d i s p e t i s e r s a r e ma t s , b a l l s , e t c . , of a b s o r b a n t m a t e r i a l s impregnated w i t h t h e i n s e c t i c i d e a r ~ d aoi . ; tened when used.

(Iz?) Viscotis pa in t -on b a i t s -- composed of a n i n s e c t i c i d e ( e .g . 7-62), a b i n d e r and s u g a r ( o r j u s t i n s e c t i c i d e i n s y r u p o r a o l a s s e s ) t o form a "pai r r t" t h a t car] be a p p l i e d wi th a b rush in s t r i p e s ,"o p a r t i t i o n s , w a l l s , p o s t - , , window a r e a s , c e i l i n g s , e t c . , o r t o s t r i p s , p l a t e s , e t c . , t h a t a r e suspended o r i t t he rwise f a s t e n e d i n s t r a t e g i c p l a c e s * 'nrlien d r y !,he p:l i , i~t may be a c t i v e f o r weeks o r months.

i n s e c t i r l d e s t o r t o x i c b a i t s : many UPS with low t o modera te t o x i c i t y and some carbarnate' may be used , t h e more i m p o r t a n t a r e shown i n T s h l e 3, w i t h W i n d i c a t i n g t h o s e t h a t a p p e a r more s u i t a b l e o r have been most w i d e l y used f o r t h e p a r t i c u l a r t y p e of a p p l i c a t i o n (WS = wster s o l u b l e ) .

WHO/VBC/86.937 page 33

For many y e a r s d i c h l o r v o s and t r i c h l o r f o n have been t h e most wide ly used i n s e c t i c i d e s f o r t o x i c b a i t s . Dichlorvos has a v e r y r a p i d e f f e c t due t o i t s fumigant a c t i o n , bu t l i t t l e r e s i d u a l e f f e c t , whereas t r i c h l o r f o n may be a c t i v e f o r months i n t h e p a i n t f o r m u l a t i o n s . C e r t a i n impure t e c h n i c a l t r i c h l o r f o n has a n a t t r a c t i v e e f f e c t a t low c o n c e n t r a t i o n s , e.g. 0.25%. Dichlorvos f o r q u i c k e f f e c t may be combined w i t h a s t a b l e i n s e c t i c i d e , e.g. f ench lorphos .

TABLE 3. INSECTICIDES USED FOR TOXIC BAITS FOR FLY CONTROL

I n s e c t i c i d e

O P compounds

d i c h l o r v o s w s d imethoa te w s tl- t r i c h l o r f o n w s +$

azamethiphos d i a z i n o n fench lorphos bromophos mala th ion n a l e d propetamphos l i i Carbamates

propoxur bend iocarb d i m e t i l a n w s me thorny l

Formaldehyde w s l i I + /

o r g r a n u l e s s t u c k on s t r i p s o r boards .

S c a t t e r i n g o r s p r i n k l i n g of t o x i c b a i t s can g i v e a s p e c t a c u l a r r e d u c t i o n of f l y d e n s i t i e s i n a few hours , b u t has t h e drawback t h a t f r e q u e n t a p p l i c a t i o n s (one t o s i x t imes a week) a r e needed f o r good c o n t r o l . Liquid b a i t d i s p e n s e r s and s t a t i o n s ( t r a y s ) f o r d r y b a i t may e o ~ t i n u e working f o r a week o r two, b u t must be placed o u t of r each of an imals and c h i l d r e n . Tbe paint-on b a i t i s t h e most v e r s a t i l e and convenient a p p l i c a t i o n . i t can be p laced wherever f l i e s congrega te , on v e r t i c a l a s w e l l a s h o r i z o n t a l s u r f a c e s , o r on suspended m a t e r i a l , and i t can have a long r e s i d u a l e f f e c t .

The v a r i o u s b a i t a p p l i c a t i o n s may g i v e a s a t i s f a c t o r y f l y c o n t r o l i n p l a c e s where f l y p r l d u c t i o n is l i m i t e d , provided t h e r e i s a n adequate d i s t r i b u t i o n of t h e b a i t i n r e l a t i o n t o the f l y a g g r e g a t i o n s . A s a r u l e t h e b a i t s do no t a t t r a c t h o u s e - f l i e s a t a d i s t a n c e , even bhen q e c i a l attractants a r e added t o t h e formulations, such a s hydrolysed o r fermented yeast: o r animal p r o t e i n ( e . g . whole egg), ammoniitnt c a r b o n a t e , s y r u p s o r m a l t , o r even t h e pheromone

WHOjVBCj86.937 page 34

nusi . ; lure . However , sui.11 a t t r a c t a n t s Inay g r e a t l y e n h a n c e t h e e f f e c t o f b a i t s u n d e r c a n d i t i L n , c : a n d , w i t k i n a r q d i u s o f a few m e t r e s , c o m p e t e w i t h t h e n a t u r a l a t t r a c t a n t odoul p r e z v n t . W a t e r i"; '1 g,md a t t r w - t a n t i n d r y z r i r r tuz td ings .

The e f f e c t o f m u s c a l u r e d o e s n o t l a s t a s l o n g a s t h a t o f t h e i n s e c t i c i d e s u s e d . A f t e r ; 3 weeks t h e a t t r a c t a i i c e i s l o s t . M u l l a a n d h i s c o l l e a g t i e s ( 1 9 7 7 ) h a v e d e v e l o p e d a S y n t h e t j F l y A t t r a c t a n t ( S F A ) , which was much more e f f e c t i v e a s b a i t i n g r e d i e n t t h a n m u s c a l u r e j

p ~ u l t r y f a r m s i n C a l i f o r n i a . The SFA c o n s i s t . ; o f 582 cclmmercial f i s h m e a l , 5% ammonir s u l f c i t l ; , 5% t r i i n e t n y l s m i i ~ r h y d r o c h l o r i d e , 1 Z l i n o l e i c a c i d and 1% i n d o l e . The a t t r a c t a n t s s l ~ ) w ! y r e l e a s e d when t h e b a i t is m o i s t e n e d . The SFA may n o t b e s o s p e c t a c u l a r i n a l l a r e a t bi t t i t i s wtorth t r y i n g . The e f f e c t o f a b a i t a t t r a c t a n t i s d e p e n d e n t a n t h e natur- a t t r a c t a n t s t h a t t!~e f l i e s a r e a d a p t e d t o and t h e c o m p e t i t i o n w i t h o t h e r a t t r a c t a n t s p r e s e n t j

tii:. a r e a .

A p a r t f r o m c h e a p r , e s s a n d e a s e o f a p p l i c a t i o n , t h e t o x i c b a i t t e c h n i q u e s h a v e t h e a d v a n t a i ! e ~ - e f o n m e n t ~ f r e s i s t 7 n ~ - 6 2 s t o t h e i n s e c t i c i d e g e n e r a l l y i s l e s s t h a n when r e s i d u a l s p r a )

&re i:sed, a n d t h a t art i n s e c - t i c i d e i n a c o n c e n t r a t e d b a i t f o r m u l a t i o n may s t i l l k i l l f l i e s eve i f t h e i r ~ e s i ~ t a z ~ c e t o t h e l i i s e c t i c i d e i s q u i t e h i g h compared t o n o r m a l f l i e s .

V . t , 5 Spice tre~itrosrlts a n d d i r e c t s p r a y i n g o f f l y a g g r e g a t i o n $

Indoor spa;e t r e a t m e n t s . F l i e s a r e q u i c k l y k n o c k e d down a n d k i l l e d b y m i s t s c (i) " - - - p

a e r i > s o l s of i n s e : ~ . : i c i d r > ~ i 3 l ~ i t i i i : l ~ ( u s u n t l y i n k e r o s e n e ) o r e m u l s i o n s . The t r e a t m e n t may t c a r r i e d w i t ? ) rlirl c r ~ n v e i ~ i e n t ,*er-osoL p r e s s u r e c a n s , hand s p r a y e r s o r s m a l l p o r t a b l e powc: s p r a y e r s . The m c i ~ r . i t r i t a b L x i n s e c t i c i d e s a r e i r y r e t h r i n s ( e . g . 0.1-0.4%) p l u s a s y n e r g i ~ ( e . 2 . 0,5--.?.3E) o r aynthet-:c p : ? r e t h r o i d s w h i c h k n o c k down b-he f l i e s i n a f e w m i n u t e s a n d d o nc pre:;i-:lt t : i r i , h : i - , ; rdu (Sciirni:itmann, 1 9 9 1 ) . However , p y r e t h r u m , p y r e t h r o i d s a n d s y n e r g i s t s a1 e x p r n s i v e 2nd n ~ y hc c:vtib::~d w i t h , o r r e p l a c e d by v a r i o u s OPs s u c h a s d i c h l o r v o s (0.1-0.5%) f e n r - h l o r ~ i i : > s (0,5-f X ) , mn 1. t h i o n ( 2 - 4 % ) , n a l e d ( L % ) , p i r i m i p h o s - - m e t h y l ( 2 % ) , p r o p e t a m p h o s (0.5 ! - t * j ? j a:- I 37 a,or-:i;! pii(i:-,; i)ii: 117 in'lny c o r l n t r i e s t h e u s e o f O P s f o r i n d o o r s p a c e t r e a t m e n t s i t - e s r r i i - t i ? d ;i:d i n s:mz :-!P3 a r e :lot p e r m i t t e d ae' a l l f o r t l i i s p u r p o s e . M o r e o v e r , t h e OPs g i t n l o s s r a p i d k.n<>ck.-down t h s n r b e p y r e t h r o i d s ?

Irlitrnr r - i I 3 1 f t > r q u i c k r e l i e f o f a f l y n u i s a n c e i n d w e l l i n g s k i t i h e r ~ s , r ; i t - a ~ m a ~ t i , ,hop4 and 37y o t h e r rdom where f l i e s may b e a p r o b l e m , a n d i n anima .;beds, . , tables; , pa c l t r y h ~ i r s c s , e t c . For f l y z o n t r o l 17 a n i m a l h o u s e s s p a c e s p r a y s are main1 ri5i.d 3 3 i s n p p L e l e t r-..;idrlal t r e a i . m e n t s ,r t o x i c b a i t s , b u t on f a r m s w h e r e t h e s e t r e a t m e n t f + l i i n - g . d ~ e t o rt s q f a ? s - e j f r e q u e n l s p a c e t r e a t m e n t s may be u s e d a s t h e p r i m a r y chemica c ~ n t r c l of e Tl e t * ~ s t l i e q r s st2ould b e J o n e whea t h e maximum p r o p o r t i o n o f t h e f l p o p u l a t i o ~ r i i i n d o o r s , e .g . i n t h e e v e n i n g s . However , e v e n o n f a r m s i n t e m p e r a t e a r e a s , wher a p o a r e n t l ! The gr r - l t m a j o l i t y o f t h e f l i e s c a n b e h i t by t r e a t i n g t h e s t a b l e s , i t may b f f i c i t t i L n # , r e tkan t e q p o r s r y c o 9 t r o l by f r e q u e n t t r e a t m e n t s , e .g . t w i c e a Wee ( s h 2 r t e r 51an t i l e j l r r - . o u i p o s i t i o n p e r ~ o d ) w i t h ' ipdce s p r a y s w h i c h h a v e n o r e s i d u a l e f f e c t , i f l y h r c e f r n s is i ~ ~ a v y .

v rcir c d o t i n u w t s - 9 n t r o l o t F l y i n f e s t a t i o n s a l l t o m a t i c a e r o s o l d e v i c e s a r e a v a i l a b l e . B means o f A t i m e s w i t c h ? r c l o c k t h e y d e l i v e r a -mall. p u f f o f p y r e t h r o i d a e r o s o l a t r e g u l a i n t e r v a l . , @ . g , e v e r y 1 5 r n i n i ~ t e s . T h e s e d r v i c - e s may b e q u i t e e f f e c t i v e , b u t r a t h e e w p - n s i v ~ . Y o r e o t e r , t h e c l n t i n u o u s u s e o f a u t o m a t i c a e r o s o l t r e a t m e n t s i n v o l v e s a n i n c r e a s e r i s k of d e v e l o p m e n t uf r e s i s t a r c e compared t o t h e u s e o f a e r o s o l s o r s p a c e s p r a y s when t h e f l " n s i t v i s t a o h i g h .

i l i 1 Otr tdoor s;)ace t r e a t - i f - n t s a r e u s e d f o r q u i c k t e m p o r a r y o r r o u t i n e e l i m i n a t i o n o f f l c o c c e r 3 e r a t i o n s , e . g . a t r e f u s e dumps, r e c r e a t i t ~ n a l a r e a s , p l a c e s w h e r e p e o p l e g a t i ~ e r , markets Emi, indi;ui;trieij ,r f r ~ r a r e a c o n t r o l i n c i t i e s and t g w r i s , e q p e c i a l l y i n e f n e r g z n c i e s .

The r y p e s 3f 3 p p ? i c a t i o n may ?x m i c ; t s p r a y i n g , foggi : lg o r t~ l t ra - low-v=l1 ime ( U L V ) s p r a y i n applied b y power u n i t s f r o m t h e g r o u n d o r from a e r o p l a n e s (I.lount, 1 9 8 5 ) . Mist b l o w e r s a r n o r e g e n e r a l l y u s e h i 1 t!lan t h e r m a l f o g g e n e r a t o r s o r m e c h a n i c a l a e r o s o l g e n e r a t o r s b e c a u s e the a r e l e s s dependent : :in a i r c u r r e n t s t o d i s t r i b z t e t h e i n s e c t i c i d e . B o r e o v e r , f o g g i n g ma

W H O / V B C / ~ ~ . 937 page 35

i l ~ t e r f e r e w i t h t r a f f i c - I n r e c e n t y e a r s ULV s p r a y i n g from t h e ground o r t h e a i r has shown g r s a t promise (!-fount, e t a l . , 1974) .

TABLE 4 DOSAGES FOUND EFFECTIVE FOR OUTDOOR SPACE TREATMENTS FOR FLY CONTROL^

d e l t a m e t h r i n d i c h l o r v o s d imethoa te f e n c h l o r v o s

re smethr in

l ~ r o v i d e d t h e f l i e s a r e n o t t o o r e s i s t a n t t o t h e i n s e c t i c i d e .

2 ~ a y be combined w i t h o t h e r p y r e t h r o i d s g i v i n g q u i c k knock-down o r s y n e r g i s t s (e.g. pb = p i p e r o n y l bu tox ide ) .

A s a r u l e ou tdoor space t r e a t m e n t s have o n l y a temporary e f f e c t , merely k i l l i n g f l i e s t h a t a r e exposed d u r i n g t r e a t m e n t , b u t n o t c o n t r o l l i n g t h o s e which a r e i n d o o r s ; a l s o , f l i e s i n s h e l t e r e d l o c a t i o n s , on t h e l e e - s i d e of b u i l d i n g s , e t c . , may s u r v i v e . The l a c k o f r e s i d u a l e f f e c t a l s o means t h a t f l i e s emerging from t h e b reed ing si tes o r invad ing t h e a r e a soon a f t e r t r e a t m e n t a r e no t c o n t r o l l e d . These f a c t o r s have t o be c o n s i d e r e d when u s i n g space s p r a y s i n a n t i f l y campaigns, and e s p e c i a l l y i f t h e o b j e c t i s t o r educe t h e f l y p o p u l a t i o n f o r a longer pe r iod . OP compounds and p y r e t h r o i d s used , and dosages found e f f e c t i v e f o r o u t d o o r s p a c e t r e a t m e n t s f o r f l y c o n t r o l , a r e shown i n Tab le 4 .

Outdoor a e r i a l space t r e a t m e n t s s h o u l d be a p p l i e d a t a t ime when o b s e r v a t i o n s show t h a t rne maximum p r o p o r t i o n o f t h e f l y p o p u l a t i o n i s exposed, u s u a l l y i n t h e morning. Da i ly t r e a t m e n t s over a p e r i o d , e.g. two weeks, may reduce t h e b r e e d i n g p o p u l a t i o n t o a p o i n t where f u r t h e r f l y c o n t r o l can be o b t a i n e d by t r e a t m e n t s a t l o n g e r i n t e r v a l s , e.g. one t o two weeks. iiouever, g e n e r a l l y i t is d i f f i c u l t t o g e t permanent f l y c o n t r o l by s p a c e t r e a t m e n t s , i f c o n d i t i o n s f o r f l y b r e e d i n g a r e f a v o u r a b l e , a s i n t h e c a s e of t h e farms i n t empera te a r e a s mentioned above. Xn p l a c e s where a g r e a t p a r t o f t h e f l y p o p u l a t i o n r e s t s o u t d o o r s a t n i g h t , t r e a t m e n t of t h e n i g h t - r e s t i n g s i t e s , e.g. t r e e s and s h r u b s , may be i m p o r t a n t .

( i i t > D i r e c t s p r a y i n g of f l y a g g r e g a t i o n s . I t i s a common p r a c t i c e i n urban a n t i f l y programmes t o s p r a y f l y a g g r e g a t i o n s on f r e s h ga rbage b o t h i n ga rbage c o n t a i n e r s and a t - - - ' cnporary r e f u s e c o l l e c t i o n s , and a s i t i s d e p o s i t e d a t t h e r e f u s e dump.

Also, garbage t r u c k s a r e r e g u l a r l y sp rayed b e f o r e they r e t u r n from t h e dump. These s p r a y '-taatments nay reduce t h e f l y d e n s i t y , b r e e d i n g and d i s p e r s a l i n connexlon w i t h t h e garbage i r q p o s a l and c o l l e c t i o n . They may be done w i t h a hand o r power s p r a y e r , a p p l y i n g a r e l a t f v e l y

w e t s p r a y , which not o n l y k i l l s t h e f l i e s h i t d i r e c t l y , bu t a l s o wets t h e s u r f a c e , g i v i n g a .l i,)rt a f t e r - e f f e c t f o r k i l l i n g f l i e s a r r i v i n g f o r o v i p o s i t i o n o r emerging l a t e r i n t h e ;fay. Trcse d i r e c t t r e a t m e n t s may a l s o have some l a r v i c i d a l e f f e c t .

A v a r i e t y o f OP compounds may be used f o r d i r e c t s p r a y i n g , i n ke rosene s o l u t i o n o r water 3-.a?jion, a t c o n c e ? t r a t i o n s o f 1-2%, e .g . ma la th ion , d i s z i n o n , f e n t h i o n , f e n i t r o t h i o n o r t h e ai-barnate dicnl: ,rvos.

WHO fVBCf86.937 p a g e 36

V.2.6 F u m i g a t i o n

' - A t o n e t i n e , v a p o u r i z l n g trICti o r l i r i d a n e by g e n t l e ~ ~ ! r ~ ; t r : ; I le , i t r :?g .-~.i;, ::I c : f f e c t i v p ,, ' o n v e n i e n t method o f f l y c r ~ t - i t r o l , e .g . i n - i r ~ i m n l i!.)!isr.;; h i i t r e s i s t a r i r i . i i ~ d t h e r i s k r e s i d u e s i n f o o d h a v e now r u l e d i t o u t .

T n t h e Lgbils, f : i r m u l n t i o c ~ s ,ind d i s p e n s e r s f o r slow r ; - i t ' a s e I F d i~* i ; l~ . : r - . r t>s ute3re di .vt?lot and Eoiir~d e F f e ; . t i v ~ ; ~ g ; i i r ts t h i ) ~ t s e - f l i e s i n r a i n s , -%ts-?h! es a::d . ? t ! ) r r? i;pa.c-; w i t h L i l n i t v c n t i l a t i o r , (air e x c h a n g e ) . Most common a r e r e s i n :,r p t ~ s t i , : s t r l - S f ~ o ~ ~ r e g u a t e d w i t h : d i c h l a r v o s . The r e l e a s e tsf J i i - h l o r v o s s l t o i l l d be F - i i r l y s ta ' - , le * , v e r a l o n g p e r i c " i t c i t lo rvos s t r i p s a r e i.t>mmortly made t o c o v e r 30 m)' o f spsce .ii:c! 'r:iy bt- e f f r r t i i i e f o r t w o t h r e e a o n t h s ' r e s i d u a l fumigar l t e f f e c t , p r o v i d e d the lverr t i iari .99 r br~ff i : ien%!;? l i - i i t e d .

I n some c o u n t r i e s t h e trse o f d i c h l o r v o s d i ; p e n s e r s i s p r c ~ b l ' h l r e i ! i.: rr>i>?-?s where food s t o r e d , p r o c e s s e d o r e a t e n , and some a l s o f o r b i d t h e use i n dwe!li;i ',s a n d I n a n y o t h e r rl: where p e o p l e s p e n d t h e i r time. D i c h l o r v o s s t r i p s a r e , ? ~ o w e v z r , i ' ; e f u l f o r g a r b a g e c a n s o t h e r r e f u s e c o n t a i n e r s .

B e f o r e p l a n n i n g t o u s e i n s e c t i c i d e s i n E l y c a m p s i g n s i r i ; n e e ? s s a r y t'? h a v e sc knowledge of t h e r e s i s t a n c e of The T o t a l f l i e r ; t o t h c ! n s ~ ~ r t i c l J e ~ : c : q u c * ~ . t f n n , p a r t ! c u l a r l y eht: 'ttouse-f l y i s t h e i i i s e c t s p e c i e s t h a t has s i ~ o v n t b s g r e a t e s t .~%ili t j r c drve!op r e s i s t a r t o i r i s e c t i c i d e s (Brown & P a l , 1 9 7 1 ; K e i d i n g , 1977) .

V. 3.1 Deve lopment a € r e s i s t a n c e

R e s i s t a n c e d e v e l o p s tltrougl-! e x ? o s u r e o f severs: ger:er:s"ono -tf f1:t.s t o i::.;rc+_i.cides, ;

I t i s t h e r e s u l t nf a s e i e c t i o n i n d b r e e d i n g o f a g s r \ + t t c a l i ; ~ ria<:?-isc.~?; zyye ?f fip. To beg w i t h t h e s e r e s i s t a n t f l i e s zclns'f t u t e o n l y a s:n;i!l f r a < . t l , - n 0"-1.1 ; ' -?t i lnt . l t?-. Ciften thc f e c u n d i t y * a n d v i g o u r i s low and t h e few s u r v i v i > r s ;?re riot n o t i t - # * d . B u t 19 t 5 e u s e o f t i n s e c t i c i d e c o n t i n u e s a n d s e l e c t i o n o f t h e r e s i s t a n t t y p e s i - r q , e a t . < d g e n e r a t i o n a f t g e n e r a t i o n , t h e r e s i s t a n t f l i e s become n o t i c e a b l e :xn:I o f p r s c t i ~ : ~ i : : i g n P f i c a n c e , f i r s t a s d e c r e a s i n g e f f e c t o f t h e i n s e c t i . , - i d e , Later g~erhapi : a s .? q u r c .tr !?ss cr)iilplt.>te f a i l u r e c o n t r o l .

F a i l i n g c o n t r o l w i t h t r e a t m e n t s t h a t u s e d t o b e e f f e c t i v e may i e i t ; .> t.o f n : * t o r s o t h e r t i r e s i s t a n c e , e . g . (1) a n u n r l s u a l l y h i g h p r o d u c t i o n I;r i l v : i . ; i : ) . t of T ; i , l r , .;o the r a t e of k i l l : c a n n o t k e e p p a c e w i t h t h e i n € l u x o f €1, Les; (2) d e f i c i e n t : i : : c f o t - m t i l a t i o n s ; 1

d e f i c i e n t a p p l i c a t i o n ; ( 4 ) h i g h t e a p e r a t u r e s or :i:hs:lrption o f !:?.;ectIi:ide i n t h e spra ! s u r f a c e s r e d u c i n g t h e r e s i d u a l e f f e c t o f t h e t r e a t m e n t s ; (5) s e i e c t 2 . v ~ riirlrtqi i c y o f p a r a s i i and p r e d a t o r s ; ( h ) r e p e l l e n c y t o f l i e s of t h e i n s r : t i c i d e f ~ r - ~ l t . i i a t : o n risr'd: ( 7 ) c h a n g e f l y b e h a v i o u r d u e t o s e a s o n o r o t h e r e n v i r o n m e n t s ! f ~ c r o r n ; a n d ( R ) charipe o f f l y hehavic d u e t o s e l e c t i v e p r e s s u r e w i t h P i l e i n s e c t i c i d e t r ~ i a t m e ; l t s ( i . e ~ : ~ ~ ~ b ~ > i i r f . ~ i i i ~ i s t n n c e ) .

R e s i s t a n c e h a s t o be p r o v e n by p r o p e r t e s t s i n which t h e Fl.!rs a r e <:;rpc.sed t o kn( d n s n g e s o f t h e i n s e c t i c i d e ur lder s t a n d a r d c o n d i t i o n s , :in d e s c r i l . e d i n t i re W140 % c t h o i i s 1

F a c t o r s p r o m o t i n g t h e d e v e l o p m e n t o f r e s i s t a n c e :o a n i n s e c t i c i d e : --

- High s e l e c t i o n p r e s s t i r e , i .P . a hf.gh p r o p o r t i s ~ n o f t h e ! ' l ~ j:gpt!inti:~n exposed i n s e c t i c i d e d o s a g e s a t w h i c h t h e r e s i s t a n t f l i e s c a n s n r v i v t . a n d b r e e d ;

- Use o f t h e same ( o r r e l a t e d ) i n s e c t i c i d e o v e r l a r g e a r e ? s ; - Use of t h e snme ( o r r e l a t e d ) i n s e c t i c i d e o v e r lni ig p e r i o d s ; - A s h o r t l i f e c y c l e (many g e n e r a t i f i n s p e r : ;ear) ; - Flxposrire of b o t h l a r v a e and ; t d l ~ l t s t . 1 t h e S,?EF: ,:I. r e l a t e d i n q e c t i c i d e s ; - The i s n l n t i o n o f t h e t r e a t e d p o p r : l n t i o n f ron: c ~ n t ~ l c t w i t ? , t:!ttre;itec! p 9 p : r i i i t i a n s ; and

I I n s t r u c t i o n s f o r d e t e r m i n i n g t h e s t ~ s c e p t i i i i t y iir rey;ist,i?;-i. (1.5 ! io r~s t . f l l i es , t s e E ' s r a b l e f l i e s , b l o w f l i e s , e t c . t o i n s e c t i c i d e s . Diicuii;e;it WH: i /VHC/S l ,8 l3 1 !98!). i p p ,

- P r e v i o u s ~ i s e o f r e l a t e d o r u n r e l a t e d i n s e c t i c i d e s and d e v e l o p m e n t o f r e s i s t a n c e t o them ( s e e c r o s s - r e s i s t a n c e , b e l o w ) .

W i d e s p r e a d u s e o f r e s i d u a l s p r a y s and l a r v i c i d e s g e n e r a l l y h a s a g r e a t e r c h a n c e o f i n d u c i n g r e s i s t a n c e t h a n o t h e r t r e a t m e n t s . Use o f i n s e c t i c i d e s a g a i n s t o t h e r i n s e c t s , e . g . i n i n a l a r i a and o t h e r a n t i m o s q u i t o p r o g r a m m e s , o r a g a i n s t a g r i c u l t u r a l p e s t s may i n d u c e r e s i s t a n c e i n h o u s e - f l ies .

V. 3.2 O c c u r r e n c e o f r e s i s t a n c e i n v a r i o u s i n s e c t i c i d e s

T h e g l o b a l s i t u a t i o n i n 1 9 8 5 i s shown i n T a b l e 5. I n f o r m a t i o n o n r e s i s t a n c e i s i n c o m p l e t e i n many a r e a s ( s e e a l s o WHO, 1 9 8 6 ) .

A p a r t f r o m t h e f a c t o r s m e n t i o n e d a b o v e t h e r e s i s t a n c e o f h o u s e - f l i e s i n a l o c a l i t y d e p e n d s o n t h e h i s t o r y o f i n s e c t i c i d e u s e i n t h e a r e a . T h e r e f o r e i n f o r m a t i o n on t h e p r e v i o u s u s e o f i n s e c t i c i d e s t o w h i c h f l i e s h a v e b e e n e x p o s e d is i m p o r t a n t .

R e c e n t i n v e s t i g a t i o n s h a v e shown t h e f o l l o w i n g i m p o r t a n t t r e n d s a n d f i n d i n g s :

R e s i s t a n c e t o o r g a n o c h l o r i n e compounds i n c l u d i n g DDT, HCH, a n d c y c l o d i e n e s is s t i l l p r e s e n t p r a c t i c a l l y e v e r y w h e r e . I n many p a r t s o f t h e w o r l d D D T - r e s i s t a n c e i s d u e t o d e h y d r o c h l o r i n a t i o n o f DDT b y t h e d i h y d r o c h l o r i n a s e enzyme (WHO, 1 9 8 0 ) . T h i s means t h a t c e r t a i n DDT-analogues, s u c h a s t r i c h l o p h e n i d i n may b e e f f e c t i v e a g a i n s t D D T - r e s i s t a n t f l i e s . R o w e v e r , U D T - r e s i s t a n c e may a l s o b e d u e t o a f a c t o r c a l l e d k d r o r s u p e r - k d r * , w h i c h makes t h e q e r v o u s s y s tern r a t h e r i n s e n s i t i v e t o DDT and a l l a v a i l a b l e K T - a n a l o g u e s . M o r e o v e r , k d r a1 s o g i v e s p r o t e c e i o n a g a i n s t p y r e t h r o i d s ( e . g . 2 0 - f o l d r e s i s t a a c e ) a n d s u p e r - k d r g i v e s q u i t e h i g h r e s i s t a n c e t o p y r e t h r o i d s , The k d r - f a c t o r ( g e n e ) i s common i n p a r t s o f n o r t h a n d c e n t r a l E u r o p e and p r o b a b l y o c c u r s i n o t h e r a r e a s a t a low f r e q u e n c y ( K e i d i n g , 1 9 7 7 ) .

O r g a n o p h o s p h o r u s - compounds (OPs) . On a g l o b a l s c a l e O P - r e s i s t a n c e h a s i n c r e a s e d g r e a t l y L I I r e c e n t years a s t o d i s t r i b r ~ t i o n , l e v e l s ' a n d compounds i n v o l v e d . M a l a t h i o n r e s i s t a n c e Ls a l m o s t u n i v e r s a l , a n d m o d e r a t e t o h i g h r e s i s t a n c e o c c u r s l o c a l l y t o o t h e r OPs d e p e n d i n g o n t h e local s e l e c t i o n p r e s s u r e , which n a y he d u e t o u s e o f OPs f o x o t h e r p u r p o s e s t h a n f l y c o n t r o l . IIigFt m u l t i - O F r e s i s t a n c e t o m o s t o r a l l OPs a v a i l a b l e i s f o u n d i n J a p a n , USA, n o r t h e r n E u r o p e and p a r t s o f c e n t r a l E u r o p e , R e s i s t a n c e t o many OPs o c c u r s a l s o l o c a l l y i n C h i n a , t h e W . & e i i ~ . .S:#- e r r a n e a n r e g i o n , t h e M i d d l e E a s t , aiid t h e C a r i b b e a n . The r e s i s " i n c e - m e c l ~ a n i s m s a n d c r o s s -

r e s i s t a n c e may d i f t e r f r o m a r e a t o a r e a , W i d e s p r e a d , h i g h r e s i s t a n c e t o t r i c h l o r f o n h a s d e v e l o p e d i n c o u n t r i e s w h e r e r e s i d u a l s p r a y s w i t h t r i c h l q r f o n h a v e b e e n commonly u s e d f o r f l y c o n t r o l , e , g . E a s t e r n E u r o p e ( ~ u p e g , e t a l . , 1 9 8 3 1 ,

Carkjamates . Carbarnd tes h a v e b e e n u s e d w i d e l y i n s u g a r b a i t s , b u t o t h e r w i s e h a v e n o t p l a y e d a n i m p o r t a n t r o l e i n h o u s e - f l y c o n t r o l , arid i n f o r m a t i o n on t h e p r e s e n t o c c u r r e n c e o f c a r h a m a t e r e s i s t a n c e i n h o u s e - f l y p o p u l q t i o q s i s more l i m i t e d t h a n f o r OPs.

C r o s s - r e s i s t a n c e t o c a r b a m a t e s is o f t e n fnund i n f l y p o p t l l a t i o n s t h a t h a v e d e v e l o p e d OP- r e s i s t a n c e d u e t o t h e u s e o f v a r i o u s Ot-'.;, b u t h i g h c < ~ r b a m a t e r e s i s t a n c e 11:is 3150 b e e n fourrd i n ; t r a i n s p r e s s u r e d w i t h c h l o r i n a t e d h y d r o c a r b o r ~ s o n l y . O f t e n t h e c r o s s - r e s i s t a n c e t o .:ar!)amates i s h e t e r o g e n e o u s w i t h a s e c t o r h i g h l y r e s i s t a n t t o c a r b a m a t e s a n d a r a t h e r s i r s c e p t i b l e n n e s e p a r a t e d by a p l a t e a u . T h e r e f o r e L D S ~ ~ may h e m i s l e a d i n g . F l i e s h i g l ~ l y r e s i s t a n t t o OPs a-td v a r i o u s c a r b a m a t e s i-iave sliown l i t t l e o r no c r o s s - r e s i s t a n c e t o metl iomyl, a c a r b a r n a t e u s e d i n a w i d e l y s o l d t o x i c f l y b a i t .

P y r e t h r o i d s ( i n c l u d i n g n a t u r a l p y r e t h r u m ) . U n t i l r e c e n t l y h i d h r e s i s t a n c e wni o n l y fc,iind !.tally i n Denmark a n d Sweden i n p o p u l a t i o n s e x p o s e d t o f r e q u e n t t r e a t a e r l t s w i t h a e r o s o l s . f i c w e v e r , s i n c e r e s i d u a l s p r a y s w i t h p e r m e t i t r i n and o t h e r s t a b l e p y r e t h r o i d s w e r e usecl f r o m 1977-78 i n t h e F e d e r a l R e p u b l i c o f Germany, S w i t z e r l a n d , a n d t h e C n ~ t e d Kingdom, h i g h p y r e t h r o i d r e s i s t a n c e d e v e l o p e d r a p i d l y and t h i s i.j l i k e l y t o t a k e p l a c e i n o t h e r are<ls. I n 7 p ( ~ s t p l a c e s k d r f o r m s s n i m p o r t a r l t c o n p o n e a t of p y r c t t h r ~ i d res i s : ; i i>c~a , 'rid i t i.; -,tri)ngl,v rc~i,mmended t o r n o i t o r f o r k d r b e f o r e c o n s i d e r i n g u s i n g r e s i d u a l p y r e t h r o i t i 5 f o r E l j co* : t r , l .

S u c h u s e i s n o t a l l o w e d i n Denmark where t h e k d r i s common. However , k d r st-erns t o b e r : t re i t ~ mos t p a r t s o f t h e w o r l d r t i ~ t s i d e ncirthttrrl ;and c e n t r a l E u r o p e , a n d rrcs i dti.11 p y r e t h r c j i d s Tay b e v e r y e f f e c t i v e i n s u c h a r e a s .

WHO/VBC/86.937 page 38

TABLE 5 OCCURRENCE OF HOUSE-FLY RESISTANCE TO INSECTICIDES~ , l985

ORGANOCHLORINE COMPOUNDS

DDT High R ve ry common, everywhere. Of ten H. HCH ( l i n d a n e ) High - i n t e r R v e r y common. d i e l d r i n High R v e r y common.

ORGANOPHOSPHORUS COMPOUNDS COPS)

mala th ion Mod - high R v e r y common. Of ten H. d i a z i n o n Mod - i n t e r R common. High R l o c a l i n Japan , USA, Europe.

t r i c h l o r f o n Mod - h i g h R i n many a r e a s . d i c h l o r v o s Mod - i n t e r R i n many a r e a s . High R l o c a l i n China, Japan , USA,

Europe, etc.

f e n i t r o t h i o n Mod - i n t e r R i n many a r e a s . High R l o c a l i n s e v e r a l a r e a s , e.@ Japan, USA, Europe. Very h i g h i n Japan.

f e n c h l o r p h o s , Mod - i n t e r R i n many a r e a s . bromophos, High R l o c a l i n s e v e r a l a r e a s i n USA, Europe, E a s t Asia . jodfenphos

- - - - - --

t e t r a c h l o r v i n p h o s Low - mod R common. High R, o f t e n H i n USA, n o r t h e r n Europe, e t c .

dimethoa t e Low - mod R i n most a r e a s . I n t e r - h i g h l o c a l l y i n USA and E deve lops s lowly.

azamethiphos Low - mod R i n most a r e a s . High R l o c a l l y i n Europe. p i r i m i p h o s l n e t h y l

-

propetamphos Low - mod R. High R r a r e .

bend iocarb Low R i n some a r e a s , h i g h R, o f t e n H , l o c a l i n Europe, propoxur e t c . C r o s s - r e s i s t a n c e from use of OPs.

me thorny l Low R i n most a r e a s . A f e w c a s e s o f h igh R i n Europe.

LR = r e s i s t a n c e , H he te rogeneous , mod = moderate , i n t e r = i n t e r m e d i a t e

WHO/VBC/86 page 39

pY RETHROIDS

e rn

p y r e t h r i n s + No - low R i n most a r e a s . I n t e r - h i g h R a f t e r u s e of r e s i r s y n e r g i s t s p y r e t h r o i d s o r f r e q u e n t u s e of s p a c e s p r a y s i n Canada and p a r t s of Eur t

Few cases i n o t h e r a r e a s .

p y r e t h r o i d s a l o n e A s above . High R may d e v e l o p v e r y q u i c k l y i n a r e a s w i t h t h e K - f a c t 0 1 ( r e s i d u a l )

LARVICIDES, I D I s

met hop rene Low - i n t e r R found i n USA and Europe , c ross-R from OPs. High R l a b o r a t o r y s e l e c t i o n .

d i f l u b e n z u r o n No - l ow R i n most mul t i -R f i e l d p o p u l a t i o n s . Cross-R f rom OPs found t h e l a b o r a t o r y .

cy romaz ine No cross-R f rom OPs. Only a few c a s e s of mod R known, b u t l i t e x p e r i e n c e f rom f i e l d u s e of cyromazine .

Kdr a l o n e g i v e s o n l y a m o d e r a t e r e s i s t a n c e , e . g . R / S ~ 3-20, depend ing on t h e p a r t i c u p y r e t h r o i d , b u t a n i n t e n s i v e s e l e c t i o n p r e s s u r e w i t h p y r e t h r o i d s , e .g . r e s i d u a l s p r a y s f r e q u e n t a e r o s o l a p p l i c a t i o n s may i n c r e a s e t h e r e s i s t a n c e t o s e r i o u s l e v e l s . I n t h e s e c a h i g h p y r e t h r o i d r e s i s t a n c e may b e d u e t o t h e i n t e r a c t i o n of k d r w i t h o t h e r f a c t o r s o r t o s u kd r . P y r e t h r o i d r e s i s t a n c e i n v o l v i n g e x t e n d s t o a l l p y r T h r o i d s t e s t e d ( N a r a h a s h i , 1% - It may b e r educed p a r t l y by p i p e r o n y l b u t o x i d e ( p b ) o r r e l a t e d s y n e r g i s t s , and i t i s u s u a l e a s t t o n a t u r a l py re th rum + pb. P y r e t h r o i d r e s i s t a n c e i s o f t e n Foilnd t o h e h e t e r o g e n e o u s a f l y p o p l ~ l a t i o n w i t h a modera t e LD SO (e .g . R/S 3-10) and a s e c t o r of r e s i s t a n t f l i T h e r e f o r e i t may n a t b e n o t i c e d , i f o n l y t h e LD 50 i s r e c o r d e d . The r e s i s t a n t s e c t o r W

i n c r e a s e by f u r t h e r s e l e c t i o n . I n p l a c e s where a e r o s c l s a r e o n l y used i n f r e q u e n t l y o c c a s i o n a l l y , s e r i o u s p y r e t h r o i d r e s i s t a n c e may no t d e v e l o p f o r many y e a r s even i f k d r p r e s e n t , a s has been s e e n on most Dan i sh f a r m s . Iiowever, t h e p r e s e n c e of E shows t h a t T h is a g r e a t p o t e n t i a l f o r p y r e t h r o i d r e s i s t a n c e t o d e v e l o p when i n t e n s i v e s e l e c t i o n p r e s s u r e a p p l i e d , i f o n l y f o r one f l y s e a s o n .

For t h e s e r e a s o n s r e s i d u a l s p r a y s w i t h p y r e t h r o i d s ( e . g . p e r m e t h r i n ) a r e n o t a l l o w e d t o used f o r f l y c o n t r o l i n S c a n d i n a v i a . However, p y r e t h r o i d r e s i s t a n c e c a n a l s o d e v e l o p with1 k d r . T h i s has r e c e n t l y been found on some f a r m s i n J apan , t h e U n i t e d Kingdom and t h e U: - On t h e J a p a n e s e f a r m s p e r m e t h r i n was used f o r s i x y e a r s f o r f l y c o n t r o l b e f o r e r e s i s t a t appea red (Kudamatsu, e t a l . , 1 9 8 3 ) .

Wi th t h e w i d e s p r e a d u s e of p e r m e t h r i n and o t h e r r e s i d u a l p y r e t h r o i d s i t i s l i k e l y t p y r e t h r o i d r e s i s t a n c e i s a l r e a d y d e v e l o p i n g i n o t h e r a r e a s even i f i t has no t been r e p o r t yet .

T h e r e i s no g e n e r a l c o r r e l a t i o n be tween OPs and p y r e t h r o i d r e s i s t a n c e . House-l ~ f > p u l a t i o n s w i t h e x t r e m e l y h i g h m u l t i - r e s i s t a n c e t o OPs, e .g . i n J a p a n and C a l i f o r n i a , U: have shown normal s u s c e p t i b i l i t y t o p y r e t h r o i d s o r o n l y a low l e v e l o f t o l e r a n c e .

I n s e c t development i n h i b i t o r s ( I D I ) , used a s l a r v i c i d e s . Recent s t u d i e s i n Denmc showed no r e s i s t a n c e t o cy romaz ine and low o r no r e s i s t a n c e t o d i f l u b e n z u r o n when l a r v a e of v a r i e t y o f f l y s t r a i n s w i t h h i g h r e s i s t a n c e t o o t h e r i n s e c t i c i d e s w e r e exposed t o l a r v a l medl t r e a t e d w i t h t h e s e IDIs.

R/S = r e s i s t a n c e r a t i o , LD o f r e s i s t a n t s t r a i n d i v i d e d by LD of t h e s u s c e p t i b l e r e f e r e n s t r a i n .

V.3.3 Nature of resistance -

Resistance is due to genetic factors (resistant genes), usually one or a few major genes for each type of resistance (WHO, 1976). The genes determine certain physiological resistance-mechanisms. Most of them are specific enzymes that detoxify the insecticide but resistance may also be due to insensitive target, e.g. acetylcholinesterase in case of OPs and caf-bamates, the nerve sheath in case of organochlorine insecticides. Fii~ally reduced penetration of the i~secticide may be a resistance factor.

Some resistance mechanisms are specific to one or a few closely-related insecticides, others are common to several insecticides (unspecific). High resistance nay be due to a single resistant gene or to the combination of two or more (interaction). The resistance of an individual fly is determined by the resistant genes and their combination in the cells (its genotype) and modified by several. non-genetic factors (age, sex, nutrition, temperature, etc.).

The resistance of a fly population is determined by the frequency (proportions) of t resistant flies of various genetic types in the population (Plapp & Wang, 1983). For the 2 development (and stability) of resistance it is important whether hybrid flies (RS) from : crossings between resistant (RR) and susceptible (SS) flies are resistant (R dominant), P intermediate or susceptible (R recessive). i

i L V . 3 . 4 Cross-resistance and multiple resistance "

j (i) Cross-resistance l ? " When fly populations are exposed to selective pressure with one insecticide (the 1 selector) they may develop resistance also to other insecticides. This phenomenon is called

cross-resistance ( H , 7 6 ) Examples: 1 *

l * 1 6 Selector : l * l i 2 Chlorinated hydrocarbons l

(a) DDT (b) HCH (li??ane)

l a

Organophosphorus compounds 1 -

(c) diazinon (d) fenchlorphos (e) dichlorvos ( f ) fenitrothion (g) dimethoate

Cross-resistance to:

methoxychlor, pyrethroids in some cases dieldrin and chlordane

parathion bromophos, jodfenphos trichlorfon diazinon fenthion, trichlorfon

I I j_ (h) Pyrethroids DDT

i In some of these cases cross-resistance is found between insecticides with a closely-

related chemical structure, in others (e.g. cases (b) and (g) the chemical relationship is less, and in case (h) there is no chemical relationship between pyrethroids and DDT.

As a rule cross-resistance is explained by a common resistance (defence) mechanism, but there are other possibilities. The problem is complicated by the presence of more than one resistance mechanism to a single insecticide, unspecific and specific resistance factors- There are often cross-resistance? on sarious levels. For example, selection with one OP compound commonly gives a moderate increase of tolerance (unspecific) to many other OPs, but not as much as to the selector (specific resistance).

On the other hand development of re~ist~~rtce to the selectJ>r may be rather slow and moderate by the use of some insecticides, e.g. diqethoate and ,~aled, whereas the selection pressure raises the resistance to high levels in several other insecticides. Such "cross- selectors" may be detrimental for d long-tsrm control prograame.

WHOIVBC186.93 7 page 41

As mentioned above, a development of resistance to one insecticide often facilitates development of resistance to another.

(ii) Multiple resistance

By exposure to two or more insecticides, either at the same time or one after the other, a fly population m y develop resistance to several insecticides, namely the selectors. This is called multiple resistance (Keiding, 1975).

V.3.5 Stability of resistance

When the use of an insecticide X is abandoned in an area, the resistance to X in the fly population will usually decrease somewhat as the selection pressure is removed. However, reversion to normal susceptibility is a very slow process, resistant-genes remain at a significant frequency, and high resistance to X develops very quickly if X is used again. Experience in many parts of the world has shown that even 20 years after DDT or HCH were abandoned for fly control, it has not been possible to resume the use of these insecticides due to the residual resistance in the fly populations. Resistance to some organophasphorus compounds (e.g. malathion and diazinon) have shown a similar stability when they were abandoned after several years. Resistance is often less stable if ft is newly developed and not been sustained for some years ("old" resistance is more stable than "young").

V.3.6 Preventing or reducing the development of resistance (WHO, 1980)

(i) The key is reduction of selection pressure with insecticides

(a) Restrict frequency of treatment. Treat only when necessary. Use source reduction, sanitation, and other non-chemical methods as far as possible.

(b) Kestric t extent of treatment. Treat only where necessary. Avoid widespread blanket treatments. Use spot treatments (including baits, strips, etc.) where applicable.

( c ) Restrtct use of residual sprays.

(d) Avoid larval (and adult + larval) pressure with insecticides useful for adult fly control.

(ii) The sequence of insecticides used in a long-term programme is of importance for the rate and extent of development of resistance. Use first insecticides with a specific resistance- factor and little cross-resistance (e.g. malathion) and last insecticides with broad cross- resistance (e.g. dimethoate and naled). AlternatLon between unrelated insecticides and between chemical and non-chemical control methods may postpone resistance development (but the use of mixtures of insecticides is not recommended),

V.3 .7 Significance of resistance for fly control

A low level of resistance (e.g. two to tenfold) may reduce the residual effect and may be apparent in use of space sprays or fumigants. iYfoderatre resistance, e.g. ten to twentyfold, may already give rise to control failures, especially where fly production or invasion is high. Nowever, the initial effect of residual sprays or direct sprays may still be good, and toxic baits may be effective. Higher resistance may cause complete failure at all practical dosages.

V.4.l Bioloaical control and rertulation of house-flv nonulations

A rich variety of predators feed on eggs, larvae, pupae or adults of synanthroplc flies and several species of small parasitoid wasps are specialists on fly pupae (a parasitoid is a parasite that kills its host) (Fig. 14).

W H O / V B C / ~ ~ .937 page 42

F ig .14 Diagram showing r h e h o u s e f l y s t a g e s and examples of i t s enemies a t t h e dung heap The l i n e s show t h e s t a g e s c h a t a r e a t t a c k e d by e a c h p r e d a t o r o r p a r a s i t o i d . Th s c a l e s a r e ~ r b i t r a r y , t h e a c t u a l l e n g t h s i n mm a r e g i v e n below.

H o u s e f l y s t a g e s : Egg: l mm, l a r v a 1:-3 mm, l a r v a 11:-5 mm, l a r v a 111: - - l3 mm puparfum: 6 mm, a d u l t : 6 mm.

X a c r o c h e l i d m i t e Z lnm S t a p h i l i n i d b e e t l e : O x y t e l u s 4 mm -- S t a p h i l i n i d b e e t l e : P h i l o n t u s 1 2 mm

p-

S t a p f l i l i n i d b e e t l e : C r e n p h i l i i s 2 0 mm lien Yellow dting f l y : Sca tophana s t - e r c o r a r i ? - = L Earwig: Lab ia m i n o r 6 mm H y d r o p h i l i d b e e t l e : Cercyon w i t h l a r v a H i s t e r i d b e e t l e : H i s t e r w i t h l a r v a 3-4 C h a l c i d wasps : S p a l a n g i a 3 mm C h a l c i d wasps: ? lu sc id i Furax 2 mm

-p-

S p i d e r : T rochosa 20 mm

WHO/V~c/86.937 page 43

A list of important natural enemies of flies are given below:

(i) Predators feeding on one or more fly stages:

Predators Fly stage attacked

Mites: Macrochelids (Macrocheles) (Fuscoropoda)

Eggs and small larvae Eggs and small larvae

Spiders (both free-living and net-spinning) Flies

Earwigs Eggs and small larvae

Mantids Flies

Beetles and their larvae, e.g. Staphylinids (rove beetles) Histerids (living in dung) Hydrophilids (living in dung)

Larvae, pupae and flies Larvae Larvae

Fly larvae: Muscoids (e.g. Ophyra, Musclna) Larvae

Fly adults: Robber flies Dung flies

Ants

Flies Flies

Eggs, larvae, pupae and newly emerged flies

Predatory wasps Plies

Reptiles (e.g. geckoes and lizards) Flies

Amphibia (e.g. toads) Flies

Birds (including chickens) Larvae, pupae and flies

(ii) Parasitoids

Small pteromalid wasps, e.g.

Spalangia spp . Muscidifurax spp. Nasonia Tachinaephagus

, Small parasitoid beetles, e.g. the staphilinid Aleochara

Pupae Pupae Pupae Larvae

Pupae

( iii ) Microorganisms

Bacteria, e.g. Bacillus thuringiensis, exotoxtn Larvae

Fungi: esp. Entomophthora ( 5 Empusa) Flies

Under relatively stable conditions o f fly-breeding habitats and in a suitable clinate these predators and parasttoids may effectively regulate the population and possibly Limlt it t o an acceptable level. This is particularly the case in tropical areas, where ants seem to p l a y an important role, and may destroy 70-90% of the potential fly population in garbage cans (Pimentel & Uhler, 1969). Predatory mites and certain beetles, e.g. Alphitobius and Carcinops may be effective in poultry manure under certain conditions, such as the manure not being too wet, but emigrating beetles may become a problem. The effect of other predators is less

WHO/VBC/~~ .937 page 44

known, b u t t h e p a r a s i t o i d wasps may a t times k i l l a h igh p e r c e n t a g e o f pupae of t h e house - f ly and o t h e r s p e c i e s .

Where such n a t u r a l r e g u l a t i n g f l y enemies e x i s t , i t i s i m p o r t a n t t o p r e s e r v e them, make t h e c o n d i t i o n s f a v o u r a b l e f o r them and t o a v o i d k i l l i n g them w i t h l a r v i c i d e s o r t r e a t m e n t of t h e i r r e s t i n g - s i t e s o r n e s t s . When manure i s c l e a n e d o u t a l i t t l e may be l e f t t o keep t h e f l y r e g u l a t i n g f auna g o i n g ('Peck & Anderson, 1970) . P r e d a t o r s and p a r a s i t o i d s s h o u l d be an i m p o r t a n t p a r t of i n t e g r a t e d f l y c o n t r o l .

A c t i v e b i o l o g i c a l c o n t r o l by r e l e a s e of wasps ( o r p r e d a t o r s ) h a s n o t been v e r y e f f e c t i v e i n f l y con t ro l . e x c e p t i n some o c e a n i c i s l a n d s , where h o u s e - f l i e s have been i n t r o d u c e d r e l a t i v e l y r e c e n t l y , o r i n t h e e x p e r i m e n t a l i n t r o d u c t i o n w i t h v e r y l a r g e numbers of wasps a t a b r e e d i n g s i t e t o p a r a s i t i z e f l y pupae. However, a t t e m p t s a r e s t i l l b e i n g made, e s p e c i a l l y i n t h e USA, t o f i n d e f f e c t i v e p a r a s i t o i d wasps f o r c ~ r t r o l of h o u s e - f l i e s b r e e d i n g i n manure and t o d e v e l o p p r a c t i c a l and economic metiiods f o r ss p r o d u c t i o n and f o r o r g a n i z a t i o n of t h e r e l e a s e s (Xorgan, e t a l . , 1978). Nany e x p e r i m e n t s have been done i n r e c e n t y e a r s on the r e l e a s e of g r e a t numbers o f s m a l l p a r a s i t i c wasps , e s p e c i a l l y S p a l a n g i a and Musc id i fu rax s p e c i e s , and i n t h e USA s u c h wasps a r e s o l d t o f a r m e r s f o r f l y c o n t r o l . The e x p e r i m e n t s have shown, however, t h a t a v a s t number o f wasps h a s t o be r e l e a s e d , e.g. 40 000-100 000 p e r week, i n o r d e r t o c o n t r o l t h e f l i e s on a f a rm, and t h e wasps c a n o n l y be produced by r e a r i n g on f l y pupae , one wasp p e r pupa. So, t h i s method o f i n u n d a t i n g f l y p o p u l a t i o n s w i t h p a r a s i t i c wasps s t i l l does n o t seem v e r y p r a c t i c a l o r economic.

I n a r ev iew i n 1986, A x t e l l conc luded :

"The u s e of b i o c o n t r o l a g e n t s f o r f l y c o n t r o l i n p o u l t r y houses i l l u s t r a t e s t h a t a m u l t i - a g e n t approach is needed . One s h o u l d n o t s e e k a s i n g l e a g e n t a s t h e i d e a l one. R a t h e r a combina t ion of p a r a s i t e s and p r e d a t o r s s h o u l d b e used . The problem, of c o u r s e , i s how t o choose t h e s e and mesh them t o g e t h e r i n a b i o c o n t r o l programme."

"Based on o u r knowledge t o d a t e , i t a p p e a r s t h a t w e s h o u l d u s e macroche l id mites, C a r c i n o p s b e e t l e s and p t e r o m a l i d p a r a s i t e s ( p e r h a p s 2 s p e c i e s ) i n p o u l t r y houses . These b i o c o n t r o l a g e n t s a r e n o t a panacea . They w i l l be s u c c e s s f u l l y used i n i n t e g r a t e d c o n t r o l a p p r o a c h which a l s o i n c l u d e s min imiz ing f l y b r e e d i n g and maximizes t h e h e t e r o g e n e i t y o f t h e manure f auna by means of p r o p e r manure management. (Manure management and b i o c o n t r o l a r e complementary a p p r o a c h e s which a r e t h e b a s i s f o r muscoid f i l t h f l y c o n t r o l i n a i l t y p e s of c o n f i n e d a n i m a l p r o d u c t i o n f a c i l i t i e s ) . The u s e of i n s e c t i c i d e s must b e i n a manner complementary t o chose approaches" . A number of s t u d i e s have been u n d e r t a k e n on t h e u s e of m a c r o c t e l i d m i t e s a s b i o l o g i c a l c o n t r o l a g e n t s of h o u s e - f l i e s ( F i l i p p o n i , 1964; A x t e l l , 1969; Rodr iguez , e t a l . , 1970) .

I n Europe t r o p i c a l s t a r l i n g s ( L a m p r o t o r n i s ) have r e c e n t l y been i n t r o d u c e d from A f r i c a and used f o r f l y c o n t r o l i n p i g g e r i e s . The r e p o r t s on t h e i r e f f e c t a r e c o n t r a d i c t o r y .

M i c r o b i a l c o n t r o l o f housef l i e s h a s a l s o been i n v e s t i g a t e d i n r e c e n t y e a r s . I n F i n l a n d a s t r a i n o f B a c i l l u s t h u r i n g i e n s i s s e r o t y p e l f o r f l y c o n t r o l i n manure has been deve loped . It p roduces a n e x o t o x i n t h a t k i l l s f l y l a r v a e and i t is c l a imed t h a t t h e s t r a i n can l i v e and p roduce e x o t o x i n i n manure ( i n c l u d i n g l a t r i n e s ) and t h u s p r e v e n t f l y - l a r v a l development o v e r a l o n g pe. 'od. However, t h e e f f i c a c y of t h i s B a c i l l u s s t r a i n and t h e p r e p a r a t i o n s c o n t a i n i n g i t i n manure under v a r i o u s c o n d i t i o n s on f a rms h a s s t i l l t o be i n v e s t i g a t e d and demons t r a t ed . C e r t a i n nematode s p e c i e s k i l l f l y l a r v a e . T h e i r p o s s i b l e u s e f o r p r a c t i c a l f l y c o n t r o l i s unde r i n v e s t i g a t i o n .

The f l y fungus , E o m o p h t l t o r a muscAe, may be a n impor t an t m o r t a l i t y f a c t o r f o r f l i e s i n a n i m a l h o u s e s , e s p e c i a l l y i n t h e l a t t e r p a r t of t h e f l y s e a s o n a s ment ioned under l o n g e v i t y i n S e c t i o n I I I . L . 4 ( d ) . However, u n t i l now i t 113s n o t been p o s s i b l e t o a a s s - c u l t u r e t h e fungus and make p r e p a r a t i o n s f o r p r a c t i c a l f l y c o n t r o l . Moreover, i t seems o n l y t o be e f f e c t i v e unde r c e r t a i n c l i m a t i c c o n d i t i o n s . Recent e x p e r i m e n t s i n Denmark have shown t h a t i n f e c t e d f l i e s can be c u r e d by s t a y i n g a t t e m p e r a t u r e s between 34*C and 40°C. The h i g h e r t h e t e m p e r a t u r e t h e s h o r t e r e x p o s u r e t ime was needed.

WHO/VBC/86.937 page 45

V.4.2 S t e r i l i t y methods and g e n e t i c c o n t r o l

I n r e c e n t y e a r s t h e r e h a s been a g r e a t i n t e r e s t i n u s i n g s t e r i l i t y methods f o r f l y ~ o n t r o l . Many c h e m o s t e r i l a n t s are e f f e c t i v e a t low dosages i n b a i t s o r by c o n t a c t , but s a f e compounds a r e n o t y e t a v a i l a b l e (LaBrecque & M e i f e r t , 1966) . Smal l -scale f i e l d t e s t s have been p romis ing and i f t h e r i s k t o man and an imals c a n be s u f f i c i e n t l y e l i m i n a t e d ( b u t t h e e x p e r t s a r e p e s s i m i s t i c ) , c h e m o s t e r i l a n t s may become a n i m p o r t a n t weapon i n t h e b a t t l e a g a i n s t h o u s e - f l i e s , e s p e c i a l l y i f b e t t e r a t t r a c t a n t s were t o be deve loped ( M e i f e r t , e t a l . , 1967).

T h e o r e t i c a l l y , r e l e a s e of mass-reared s t e r i l i z e d male f l i e s m y be used e f f e c t i v e l y i n c o n t r o l schemes (LaBrecque & Weidhaas, 1970) . However, t h i s s o p h i s t i c a t e d method is n o t r e a l i s t i c f o r o r d i n a r y f l y c o n t r o l p r o g r a m e s . I t r e q u i r e s a thorough s t u d y o f t h e eco logy and dynamics o f t h e f l y p o p u l a t i o n , a h i g h l e v e l of o r g a n i z a t i o n and e x p e r t i s e f o r t h e p r o d u c t i o n and r e l e a s e of s ter i le fLSes and f o r m o n i t o r i n g t h e e f f e c t (Weidhaas, 1968). Moreover, t h e method is p r i m a r i l y s u i t e d t o i s o l a t e d f l y p o p u l a t i o n s (e.g. on i s l a n d s ) t h a t c a n be reduced by o t h e r means and where t o t a l e r a d i c a t i o n is f e a s i b l e (Pausch, 1972). T h i s a l s o a p p l i e s t o g e n e t i c c o n t r o l of h o u s e - f l i e s , e t c . , i n which e x t e n s i v e r e s e a r c h h a s been c a r r i e d o u t i n t h e United S t a t e s o f America. The t h e o r e t i c a l p o s s i b i l i t i e s a r e h i g h l y i n t e r e s t i n g , bu t t h e y d o no t o f f e r p r a c t i c a l s o l u t i o n s t o t h e f l y problems of c i t i e s , towns and farms f o r t h e n e a r f u t u r e (Wagoner, e t a l . , 1974).

V. 4.3 Trapp ing

Lack of s u c c e s s w i t h i n s e c t i c i d e s f o r f l y c o n t r o l h a s r e v i v e d t h e i n t e r e s t i n u s i n g t r a p s (Davidson, 1962; Thimijan, e t a l . , 1970) . Traps and " e l e c t r o c u t o r s " w i t h b l a c k l i g h t o r o t h e r t i g h t as a t t r a c t a n t s a r e f r e q u e n t l y t r i e d and m y be q u i t e e f f e c t i v e a g a i n s t b low-f l i e s i n shops , d a r k e n t r a n c e s and o t h e r i n d o o r s i t u a t i o n s . However, t h e i r a b i l i t y t o l u r e h o u s e - f l i e s and r e d u c e p o p u l a t i o n s i s r a t h e r l i m i t e d and v e r y dependent on l o c a t i o n , t e m p e r a t u r e and t h e p h y s i o l o g i c a l c o n d i t i o n s of t h e f l i e s ( s e x , a g e , m a t u r i t y , n u t r i t i o n , e t c . ) . Exper iments w i t h narked f l i e s i n animal houses showed t h a t e l e c t r o c u t o r s w i t h "b lack l i g h t " o r o t h e r f l u o r e s c e n t l i g h t t u b e s used a t t h e recornended r a t e k i l l e d a small f r a c t i o n of t h e h o u s e f l i e s and were n o t a b l e t o c o n t r o l t h e f l y p o p u l a t i o n (Claugh, 1980). To do t h i s a h igh number of e l e c t r o t r a p s have t o be used o r t h e e l e c t r o t r a p s may be combined w i t h a chemica l a t t r a c t a n t , e.g. muscalure o r t h e S y n t h e t i c F l y A t t r a c t a n t . The development of more e f f e c t i v e b a i t s h a s a l s o improved t h e p o s s i b i l i t y of u s i n g b a i t e d t r a p s ( o r t o x i c s b a i t s ) .

V I . FLY SURVEY NEmODS

I n o r d e r t o p l a n and e v a l u a t e f l y c o n t r o l p r o g r a m e s i t is n e c e s s a r y t o o b t a i n a r e l i a b l e assessment o f f l y p o p u l a t i o n d e n s i t i e s * and t h e i r changes i n r e l a t i o n t o t h e c o n t r o l methods used. T h i s i n v o l v e s p r e - c o n t r o l s u r v e y s t o de te rmine where, when and how f l y c o n t r o l should be c a r r i e d o u t , and p o s t - c o n t r o l s u r v e y s t o e v a l u a t e t h e e f f e c t and s u c c e s s o f t h e f l y c o n t r o l o e a s u r e s .

Pre-con t ro l s u r v e y s i n c l u d e d e t e r m i n a t i o n o f t h e impor tan t s p e c i e s t h a t c a u s e problems, t h e i r b r e e d i n g s o u r c e s and p l a c e s , s e a s o n a l f l u c t u a t i o n s , d i s t r i b u t i o n and h a b i t s of a d u l t s ( i n c l u d i n g n i g h t - r e s t i n g ) , t h e a d u l t d e n s i t y i n d i f f e r e n t a r e a s and p remises , and t h e i n s e c t i c i d e s u s c e p t i b i l i t y . P o s t - c o n t r o l s u r v e y s mainly i n v o l v e assessment o f a d u l t d e n s i t i e s znd i n s e c t i c i d e s u s c e p t i b i l i t y .

There a r e s e v e r a l methods f o r e v a l u a t i n g changes I n a d u l t d e n s i t i e s and t h e most impor tan t I r e mentioned below. Noae of t h e methods w i l l measure t h e a b s o l u t e number of t h e f l y a o p u l a t i o n f , but. w i l l g i v e a n index. For c h o i c e of method i t is Important t h a t i t f i t s t h e s i o l o g y and behaviour of t h e Local f l y p o p u l a t i o n s , t h n t i t a s s e s s e s Ely d e n s i t y a t t h e p l a c e s +here t h i s i s of i n t e r e s t , t h a t t h e s i z e o f t h e sample is a d e q u a t e t o r e p r e s e n t t h e a r e a , t h a t :he method i s e a s y and qu ick t o u s e and t h a t i t is a s o b j e c t i v e and s t a n d a r d i z e d a s p o s s i b l e . Zometimes a combinat ion of iaerhods is n e c e s s a r y t o g e t a comprehensive p i c t u r e of t h e f l y

T h i s r e q u i r e s more e l a b o r a t e methods i n v o l v i n g c a t c h i n g , marking, r e l e a s i n g and - e c a p t u r i n g t h e f l i e s .

W H O / V B C / ~ ~ . 937 page 46

d e n s i t i e s i:-i i r n p o r t a ~ i t s i t e s . However, i t i s e s se r - i t i a l t h a t t h e same inethod be u s t l ~ r o u g i t o i ~ t f o r s u r v e y s ~ s s e s s t h e changes of f l y d e n s i t y i n t i m e , e s p e c i a l l y b e f o r e a , a f t e r c e o t r o l ope r<+t i o n s .

The m r t ! ~ o d s depend e i t h e r on c ~ u i l t i n g u r e s t i ina t i r tg t i le nrimber of F l i e s on s e l e c t e d a r e , o r a t t r a c t a n t s , t r a p p i n g f l i e s , c a t c h i n g f l i e s , o r c o u n t i n g f l y s p e c k s . A compar ison of tl a d v a n t a g e s and d i sadvar l t ages of t h e rnethods d i s c u s s e d i s stiown i n T a b l e 6 .

V l . 1 . Coun t ing f l i e s o.i s e l e c t e d -&reas ijr : i t t r a c t a n t s

F i l e s a r e c.!,;icltrttl o i l s ,;r l i t c h i t it; j t i : i :*t.a c:vcr : ~ : i t i i ~ a l Fly c o n c e n t r . i t i o : ~ s . The nethc i s one of t i re ;n:>.>t w i d e l y trsed, si t1 . -e i r u,is :ir.;:ribt>d by Sztiddar i n 1947. Tile g r i l l , o f t t r e f e r r e d a s -t .si:trdder g r i l l ( F i g . l4 ( a ) ) C O z i Y i ~ t : )F L6-24 wooden s i a r s , f a s t e n e d ; e q u a l i n t e r v a l s t o cover ~ l r e a u o f from 0-9 m" (":g g r i l l ) d ~ w n t o 0.2m2 ( s m a l l g r i l l ) . Ti; b i g g r i l l i s tor t . ju tdi , , j r use, 1:)lti i :r ipr- .+ctl t ,s7, f . ) r indiji;t r ise. For g e n e r a ? trse n s m a l l r

mediun: s i z e d g i s b . F - m-tlk::ss :J cociflt: t h e g is lowtlr-ld O v e r R i: coilceri tr . i t ia: : . TI:r a r e I i~ . ; t . i r i ie~i t rtitiirr! ci, t i le ?Ct rac ta f I t and s e t t : t 1 . I - I r 1 7'11:; .-I . nb i r t l i s t . S g iCi ses.ioc!s is c r ~ u n t e d . Tr-t eac

L jr. : g * , ; ~ I P ":if ":it" /:ig'!rst. f t y q ~ l l ~ e i i i . r ? $ t i o n ~ f < > ~ r l d ar ! :>c-;~i i~) ' cct.in:.i dr;. !.;.3tii- [?I; tiirc;. i . ?

r r s t r l t av.-tr ia;e!i, ;fi each . r ren :i:.>re be t ixi:d "it .it is)‘;^ :irld rer tdon (moving) s t a t i o n : ~ ; ~ ~ ~ ~ r _ s cc fii*eli ~ ~ a : i . ~ n i ; 3k3:lti j :it !r ::I,:- is:,> (,C t ' e [ ~ , r c . j t : ip i? rnhlVty ,

Fly grill count

Survey method

Simple, rapid, versatile for assessing fly concentrations. Many sites can be sampled* Well established and tested method .

Advantages

Identification of flies difficult. Much dependent on the chance aggregation of flies, and only measures the momentary density. Grills cannot be used everywhere, e.g. where flies concentrate on animals. Unreliable results at very low and very high densities.

Counts on Simple, rapid, versatile, available surfaces etc. (see VI.l.3).

1 Counts on baits f I

Baited traps Sample over a period. Flies obtained for identification, sus- ceptibility tests, etc.

Subjective, depends on training and experience.

Simple, useful at low densities.

Dependent on location and bait. May attract flies from other premises. Requires construction and maintenance of traps.

More complicated than the grill. Dependent on bait attraction.

Sticky traps Sample over a period. Flies obtained for identification. Sensitive to population changes. Effective at low densities.

Catch much dependent on location. Time consuming and messy. Requires purchase or preparation of sticky strips, etc. Overloading by flies.

1 ~ight traps Sensitive to population changes.

Expensive, can only be used indoors. Attractiveness varies from place to place and with temperature.

Catching flies Flies obtained for Unreliable for quantitative sampling. identification, susceptibility tests etc.

The procedure outlined on page 46 is the one most recommended and used in various parts of the world, but the interpretation of grill counts may vary from place to place. I n some b~remises, e.g. restaurants, a count above three may be unacceptable, whereas in a dairy barn counts below 20 %ay be acceptable.

1,ctcal modifications of the grill c o u n t riletbod a r e used, e.g. leaving the grill far a longer time i n each place or r v p n using tt as a permanent counting station. However, thece modifications are against the idea of the grill method: to give quick counts ~ j f fly

l cs>ncentrations wherever they occur* d 1

1 f

WHO/VBC/86.9 37 p a g e 48

V1.1.2 C o u n t s of f l i e s l a n d i n g on b a i t s

D i s h e s , t r a p s , p l a t e s , s t r i p s , e t c . w i t h a f l y a t t r a c t a n t a r e e x p o s e d f o r a s t ~ i t a b l e t i m e , e.g. 2-00 m i n u t e s , a n d t h e f l i e s l a n d i n g on t h e b a i t a r e c o u n t e d . B a i t s may b e s y r u p , m o l a s s e s , m i l k o r h y d r o l y s a t e o f p r o t e i n .

The method h a s b e e n u s e d a g r e a t deal f o r e s t i m a t i n g t h e e f f e c t of f l y c o n t r o l i n a n i m a l i i o u s e s , e s p e c i a l l y i n t h e USA, b u t i s n o t so v e r s a t i l e and q u i c k a s t h e f l y g r i l l metfiod, and n o t s u i t a b l e f o r c o r n u n i t y f l y s u r v e y s .

VL. l .3 C o u n t s o r e s t i m a t e s o n a v a i l a b l e s u r f a c e s

The rlurnber of f l i e s may b e e s t i i n a t e d a t avaI la3Le ( 1 L. . T u a t l n g ) Ely c i ~ ~ i c r r l t r * t i o n s to g i v e r a p i d v i s u a l e s t i m a t e s c o r r e s p n n d l n g t o g r i l l i :oitnts, To d o t i t i s r e l i ; i b l y $1 good d e a l of t r a i n i n g i s r e q u i r e d .

Anot l l e r method is t o c o u n t o r e s t l i s a t e t h e niimher af f l i e s o n a r:umber of f i r e d a r e a s , w h e r e f l i e s a r e known t o c o n c e n t r a t e , e * g . 21% a n i m a l s , s t a n c h i o i ~ s , p:lnrtitio:ir o r f e e d i n g t r o u g h s Ln s t a b l e s - T h i s may be d o n e where t i l e d i s t r i b u t i o n n f f l i e s i s r e - i s o r ~ a h l y c o i ~ s t a n t , b u t t h e t i m e o f day , t h e weather :itid t!ie tdi,rh i n t h e s t 2 h I . e ( f e e d i n g , c l e a n i n g , e t c . ) a r e Jmpnr t an t f a c t o r s , T h e m e t h o d dass n o t l i ln? i t s e l f v e i l f i y :surveys 1~1 t o w n s aiid c i t i e s .

T - i r t p i g g e r i e s and ctzv sheds it. te toprra t t . c o u n t r i e s ( e , g . D ~ n w a r k ) where ix:rat of t!;e f l i e s

a r e I n t h e a n i m a l s o r c l o s e by iil the d a y t i m e , a n e s t i m a t e o f eFie nt1rnb-r of F l i e s p e r a n i m a l may h e u s e d for t h e f l y i n d e x .

V I - 2 . T r a p p i n g f Lies

VI .2 .1 B a i t e d t r a o s

The cornton t y p e of f l y t r a p , a c y l i ~ - i d r l ~ : a l s c r e e n - w i r e cage wiih an i . ~ v i i r : -ld-cclne e n t r a n c e ( F i g . I5b) Is u s e f u l f:>r fly s u r v e y s , e s g c t - t a l l y f o r c j r r a l i ~ a t i v e samyl i t tg of t h + f f t f a u n a f o r i d e r ; t ! f i c a t f o n ~ R e c e n t l y a s i m p l e t r a y inildc o f a 3-51, l i t r e p l i i s t i c j:rg w i t ! ? four 5-cm- d i a ~ n e c e r access hohes i i i is been i : ~ t r s , d u c e d bp Burg ~ i l d A x t e i l jl.YS4) F . ) r 8*1c;nit'?:ifig f l y d e m l t ber i a ? p u c l r r y i i i iuses . The t r a p >;.as h:3l t e d yii-!I a g r a n u l n t e cooc;<i n i , G 3 , . ?LS% p?ui.:arnone and 1% m e t i i ~ ~ m y l ~ The re! i < i h i l i ey f o r qr isr~t i t q t i v c - c~st imn:~?t- oar' f l y p:;;:~:.r: i . ;,;;s b a i t e d t r a p s i s depeqdrrl t on tile i:i;ml-,er.; atad I+ t :a t i r i r~ I,:' t ' le t r a p 9 ; i a d t i \ e i (>caI (-I i i i - y -if tile b a i t . M ." 8 , 3,:,Leirvpr, baited trap.; ~ ; r y : i~ t r+ . . ' i FIIFs t!j;r: ~ : , . ~ : d .; i t i:rlr?ia? l y i16: i n L);:? , 2 ~ : s ~

WHO/VBC/86.937 page 49

V1.3. Catching flies

Sweeps of net

Netting flies is useful for collecting specimens for identification, susceptibility tests, etc., but standard sweeping for quantitative estimates of fly population is difficult and unreliable.

VI.3.2 Movable suction device

A suction device like a big vacuum-cleaner may be used for collecting and monitoring fly densities in animal houses in connection with experiments. However, for routine surveys the device is not practical.

v11 3.3 The fly cone

A cone made of wire netting with a diameter of 75 cm can be used for sampling flies on natural attractants (garbage, manure, etc.). The fly cone is good for collecting specimens in such places, but not suitable for general surveys, as there are many places where it cannot be used to collect flies.

VT.4 Counting fly specks

Suspension of paper, cardboard, plastic, glass, etc., in fly infested premises and counting the number of fly specks deposited per day has been considered in some places for estimation of fly densities, but the experience is not encouraging.

WHO/VBC/86.937 page 50

V I Z . GLOSSARY

ASTENXAE

CAYPYLOBACTERLOSIS

CONTROL

DENSITY (of f l i e s )

DIPTERA

D I S P E R S I O N

GARBAGE

P a i r e d apperldiigc o f head of i i t uec tu arrd o r h e r a r t h r o p o d s . U s u a l l y w i th za; iy segmen t s . In house-f l i e s three segments and a b r i s t l e . Antennae c a r r y chemoscnsory o r g a n s .

A s l i ? n d c r b r i s t l e , usually found d o r s a l l y on the t e r m i n a l j o i n t of the i3i?teii:l:io o f c e r t a i n Z)iptercl.

Cont rf-,! mii:i.iilres by means 3 f 1ivt11g organisms.

The j c j i ~ ~ l n t i : a t i v e ) r e l a t i o n 03% d e v e l a p m r n t , r e p r o d u c t i o n and s u r v i v a l 11 17 (,i-giiii: S I ~ p , j t t b i ; l t i ~ i ~ ot org-inisrls ti) f a c t o r s i n t h e envi ronment .

Z a f e r t i c i n L t" A Craa-r!egative b a c t e r i a Campylobacter f e t u s c a u s i n g dy-,er-ttcry.

Of iiisects for other u n d e s i r a b l e ani:naLs); t h e r e s t r i c t i o n of t h e p o p u l a t i c n d e n s i t y o f s u c h i n s e c t s t o a l e v r f below t h a t a t which t h e y can be hnriafu2 t o t h e i n r i ? r e s t s of man.

Number o f flies per given area o r other u n i t .

An o r d e r of i-~scct; c o n t a i n i n g t h e two-winged flies which have o n l y t h e a n e e r i o r p a i r 3 E wings w e l l deve loped .

The rnovt=nerTts ( - E flies iri at11 a r o u n d a l o c a l i t y o r a r e a i n which they emerged c r a r e found at a g i v e n t i m e .

A d e v i c e to k i l l flies by a g r i d o f w i r e s w i t h a n e l e c t r i c charge . E i e c i r o c u t o r s a re U S ~ I X ? ~ ~ i f r r ~ ~ i d e d with t c b e l i g h t which may a t t r a c t some F ? . . L 1 G S .

Tire iq ,~vezt . i l t = i t i t F r o m a g i i r i ? ~ ~ locality o r a r e a .

. . .'.> : . j - : : , i~ ." I P?:* ~ ~ r t ' : , i r , + P _ i &>:I, . .. .. , i t ; ~ i t : r i : ;c- r : r i r is v f r.;',:ii, market was t e s

f r ' #a : l , > i l i r - ;<3 ,>[ ; , ) r+g<? ,3".(.i ;;lie ,> f f~),>(j* C

t:r ;rc,i-::s .:' ! h; p!.;: I f ' ! a c>~ i i c .~~n in t ] i eSp Nemdtnda and ca-;i:=~ci.iliy p,cr.a.;';tr.;-

WHO/VBC/86.937 page 51

HUMIDITY OR The content of water vapour i n t he a i r measured a s a percentage of RELATIVE HWIDITY t h e content of s a t u r a t e d a i r (100% RH).

IMIGWTION The movement i n t o a given l o c a l i t y o r a rea .

INTERFERTILE Subspecies which a r e a b l e t o produce f e r t i l e o f f s p r i n g when a member of (SUBSPECIES) one subspecies mates with a member of the o the r subspec ies ( see a l s o

spec ies ) .

INSECT DEVELOPMENT Chemicals which i n h i b i t the development of l a rvae o r pupae i n t o a d u l t s o r INHIBITORS (IDI) of eggs i n t o l a r v a l . The I D I s a r e o f t e n included i n t he term i n s e c t

growth r e g u l a t o r s (IGR).

KDR-FACTOR - A gene t h a t is involved i n t he mechanism of i n s e c t i c i d e r e s i s t a n c e , reducing the s e n s i t i v i t y of the nervous system t o t h a t i n s e c t i c i d e and i t s analogues.

LARVICIDES Chemicals which k i l l l a rvae d i r e c t l y o r by preventing them from developing i n t o a d u l t s ( s ee V , 2, l ) .

NONENCLATURE The s c i e n t i f i c (La t in ) names given t o spec i e s , genera, f a m i l i e s , e t c . of animals and p l a n t s .

OLFACTORY Associated wi th t h e sense of s m e l l .

PATHOGENS

PHEROMONE

Microorganisms (germs) such a s v i r u s e s , b a c t e r i a , protozoa and eggs and c y s t s of worms, which can cause d i sease i f man is in fec t ed .

Chemical subs tance t h a t i s produced by an animal and func t ions a s a communication which a f f e c t s the behaviour of o t h e r i n d i v i d u a l s of t he same spec ies .

PREDATOR An animal which preys upon i n s e c t s o r o t h e r animals.

PREOVIPOSITION The time from t h e emergence of t he female f l y from the puparium and PERIOD u n t i l i t is a b l e t o s t a r t l ay ing eggs.

PUPARIW A barrel-shaped case formed by the cont rac ted and hardened s k i n of t he t h i r d l a r v a l i n s t a r and i n s i d e which the pupa develops.

REPRODUCTIVE The t h e o r e t i c a l capac i ty of increase i n numbers of a p a i r of f l i e s POTENTIAL i n a given t i m e , e.g. a year.

RESIDUAL TREATMENTS Treatments wi th i n s e c t i c i d e formulat ions having a long-term e f f e c t (weeks o r months).

RESISTANCE TO Resistance i s a g e n e t i c a b i l i t y i n an i n s e c t populat ion t o t o l e r a t e INSECTICIDES higher dosages of an i n s e c t i c i d e than normal, developed a s a consequence

of i n s e c t i c i d a l t reatments .

SALMOfJELLA A genus of t he family Enterobacter iaceae , pathogenic t o man causing typhoid and paratyphoid fever and food poisoning.

SGLEROTIZED Hardened c u t i c l e .

SCREENING The use of f l y s c r eens o r n e t s f o r excluding f l i e s .

SWTGELLA A genus of the family Enterobac ter iaceae , members of which cause b a c i l l a r y dysentry i n man.

' rile :;i:?;;l i r q r a , l i t (,f t - l a s s i f j c a t i i i a ~ " o ; o i i i d i ? ~ y . ! ~ i - ~ l , I ,i , C ' i t3 gr > L I P ~ h * : : ; ~ , v i c , i 3 ~ ~ c 2 r s i j l e gl .t>a~itt: . j t fn,1tt33 1 l : 3 1 e b * ,; i , t + - ;r3reed ( i f l i c J : s,,;?tl-cir.r:d iE: -,;>.xce t!.le], ilL1t ~ ~ t , ' ' . bt't>.,j ~: i ::! sjr:; t t l i ' 4 a a S O f :3t1>er trsiilj)s jSpe,-ii.s). ';pp< ie, a,~%,- he divic"t.:I i...:c\ s t i 3 i s ; . 8. 'd!;icii d i f f 2 c itl ~. . . . - -- . -- , e t . - - t ) i i ~ i t L~ ~ h l i a L*: i t <Sec L?~TEKFIIKTZL.E),

TENSILS (FOR FOOD)

< : ~ s s c I ? ~ I ~ . i t i t > c l of < ~ - f a a l : > 1:7<! p l + i t i t ,: t t i v f .l,>:! I ! I C < : g , j> '> : : i ' :+ , g ln~?T, i , fnmi l i e s , e t c .

F l d t ? ~ a:?d t;tlterr ! l :~ ;~ : t j ifr . i iv i : l r "Z; ; , x i t , .V ,-~::;j<>;~s: !::%:IJ* {lorax alld abdomen. T h e e L l . ~ r . l x c t r r i e s t hr. !PR.: $:id wlnqs,

‘4 t r i > p i c l i d i re; i~ci :.:,?.~-.ed by spi: i.‘f? .-ni~;f,ile k , qfh j ,, t t l r + ~ ~~3 bone :nani. r'est.it ion.;.

WHO/VBC/86.937 page 53

Abstracts of most references up to 1972 may be found in West and Peters (1973).

1. Anderson, J.R. 6 Poorbaugh, J.H. Refinements for collecting and processing sticky fly tapes used for sampling populations of domestic flies. Journal of economic entomology, 58: 497-500 (1965). -

2. Ascher, K.R.S. The attraction of the Levant house-fly Musca vicina Macq. to natural breeding media. Acta Tropica, 15: 1-14 (1958).

3. Ascher, K.R.S. 6 Levinson, Z.H. Chemicals affecting the preimaginal stages of the housefly. 1. Review of the literature. %vista di parassitologia, ll: 235-259 (1953).

4 . Axtell, R.C. Macrocheklidae (Acarina: Mesostigmata) as biological control agents for synanthropic flies. WHO/VBC/69.119, 1969, 17 pp.

5. Axtell, R.C. Status and potential of biological control agents in livestock and poultry pest management systems. Miscellaneous publications of the Entomological Society of America, (1986) (in press).

6. Bidawid, S.P., Edeson, J.F.B., Ibrahim, J., Matossian, R.H. The role of non-biting flies in the transmission of enteric pathogens (Salmonella species and Shigella species) in Beirut, Lebanon. Annals of tropical medicine and parasitology, 72: 117-121 (1978).

7. Brown, A.W.A. & Pal, R. Insecticide resistance in arthropods. 2nd ed., Geneva, World Health Organization, Monograph Series No. 38, 1971, pp. 225-387.

8 . Burg,.J.G. & Axtell, R.C. Monitoring housef ly, Musca domestis, populations in caged- layer houses using a baited jug-trap. Environmental entomology, 2: 1083-1090 (1984).

9 . Busvine, J.R. Insects and hygiene. The biology and control of insect pests of medical and domestic importance. London, Chapman & Hall, 1980, pp. 190-211.

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2 4 . Davidson, A. Trapping houseflies in the rural areas of Israel. Rivista da parassitologia, 23: 61-70 (1962).

15. Dipeolu, 0.0. Field and laboratory investigations into the role of the Musca species in the transmission of intestinal parasitic cysts and eggs in Nigeria. Jvurnal of hygiene, epidemiology, microbiology and immunology, 2: 209-214 (1977).

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WHO/VBC/86.937 page 54

17. Eastwood, R.E., Kada, J.M., Schoenburg, R.B., Brydon, H.W. Itlvestigationa or1 fly c(>ntrol by c . j ~ y o s t irig poultry manures. Journal of economic entomology, 60: W 88-89 (1967).

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i

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-.----m-

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56. Peck, J.H. & Anderson, J.R. Influence of poultry-manure-removal schedules on various Diptera larvae and selected arthropod predators. Journal of economic entomology, 63: 82-90 (1970).

57. Pickens, L.G. Morgan, N.O., Hartsock, J.G., Smith, J.W. Dispersal patterns and populations of the house fly affected by sanitation and weather in rural Maryland. Journal of economic entomology, 60: 1250-1255 (1967).

58. Pickens, L.G., Morgan, L.O., Miller, R.W. Comparison of traps and other methods for surveying density of population of flies in dairy barns. Journal of economic entomology, 65: 144-145 (1972). -

59. Pimentel, D. & Uhler, L. Ants and the control of houseflies in the Philippines. Journal of economic entomology, 62: 248 (1969)

60. Plapp, Jr., F.W. & Wang, T.C. Genetic origins of insecticide resistance. In: Georghiou, G.P. & Saito, eds. "Pest resistance to pesticides", New York, Plenum Press, 1983, pp. 47-70.

61. Raybould, J.N. Further studies on techniques for sampling the density of African housefly populations. 1. A field comparison of the Scudder grill and the sticky-fly trap for sampling the indoor density of African house flies. Journal of economic entomology, 59: 639-644 (1966a). -

62. Raybould, J.N. Further studies on techniques for sampling the density of African house fly populations. 2. A field comparison of the Scudder grill and the sticky-fly trap method for sampling the outdoor density of African house flies. Journal of economic entomology, 2: 644-648 (1966b).

63. Rodriguez, J.G., Singh, P-, Taylor, B. Manure mites and their role in fly control. Journal of medical entomology, -- 7: 335-341 (1970).

64. Rosef, 0. & Kapperud, G. House flies (Musca domestica) as possible vectors of Campylobacter fetus subsp. jejuni. Applied and environmental mPcr.tbinlogy, (15: 381-383 - (1983).

65. Rosen, P. & Gratz, N.G. Tests with organo-phosphorus dry sugar baits against houseflies in Israel. - Bulletin of the World Health Organization, 20: 841-847 (1959). -

v 66. Rupes, V. et al. Insecticide resistance in housefties Musca domestica (L.) in

P

Czechoslovakia. International Pest Control, 25(4): 106-105 (1983). -

j7.

58.

59.

70.

r1.

?2*

73.

" 4.

'5.

'6.

'7.

'8.

'9.

10.

'l.

2.

3.

WHO/VBC/86.937 page 57

Sampson, W.W. Insecticides used to control house-fly larvae. Journal of economic entomology, 49: 74-77 (1956).

Saeca, G. Comparative bionomics in the genus Musca. Annual review of entomology, 1975, 9: 341-358 (1964). -

Sacca, G. Speciation in Musca. In: Wright, J.W. & Pal, R., eds. Genetics of insect vectors of disease. Amsterdatn, 1967, pp. 385-399.

Schlein, P. & Calun, R. Male housefly (Musca domestica L.) genital system as a source of mating pheromone. Journal of insect physiology, 30: 175-177 (2984).

Schmidtmann, E.T. Waterbase and aerosol concentrate application of permethrin for house fly control in New York dairy housing. JJ, 2: 440-408 (1981) *

Schoof, H.F. How far do flies fly? and what effect does flight pattern have on their control? Pest Control, 27 (4): 16-24, 66 (April 1959).

Schoof, H.P., Mail, G.A. & Savage, E.P. Fly production sources in urban colamunities. Journal of economic entomology, 47: 245-253 (1954).

Seudder, M.I1 (1947) A new technique for sampling the density o f housefly populations. Public health reports, 62: 681-686 (1947).

Silverly, R-E. & Schoof, H.F. Utilization of various production media by muscoid flies in a metropolitan area. I. Adaptability of different flies for infestation of prevalent media. Annals of the Entomological Society of America, 48: 258-262 (1955).

Spiller, D, Nutrition and diet of Muscoid flies. Bulletin of the World Wealth Organization, 2: 551-554 (1964).

Thimijan, B.W., Pickens, L.G., Morgan, N.O. A trap for house flies. Journal of economic entomology, 63: 1030-1031 (1970).

Wagner, E.G. & tanoix, J.N. Excreta disposal for rural areas and small comunities. Geneva, World Health Organization, Monograph Series MO. 39, 1958, 187 pp.

Wagoner, D.E., McDonald, T.C., Childress, D. The present status of genetic mechanisms in the housefly Musca domestica L. In. Pal, R. & Whitten, M.J., eds. "The use of genetics in insect controlw, Amsterdam, Elsevier, North Holland, 1974, pp. 183-1979

Weidhaas, D.E. Field development and evaluation of chemosterilants. In: La Brecque, G.E. & Smith, C.N., eds. "Principles of insect chemosteriltzation". Amsterdam, North Holland, 1968, pp. 280-284.

Weidhaas, D.E. & LaBrecque, G.C. Studies on the populati~n dynamics of the housefly, Musca domestica L,, Bulletin of the World Health Organization, 43: 721-725 (1970).

West, L.S. The housefly, its natural history, medical importance and control. Comstock, Ithaca, New York, 1951, 584 pp.

West, L.S. & Peters, O.B. An annotated bibliography of Yusca domestica Linneaus. Folkestone and London, Dawsons, 1973, XI + 741 pp. (5720 references).

, . i' +. ~ ~ I I ~ Z C L >:I, R. k-. , L . ; L . , G a ~ ~ ~ ~ f i ~ ~ ~ ! ~ ~ p i 1 ~ : i i , A. , ,,akj<+z :t.nam, ~C. fio~sefly p o p ~ k l a t it):~s their d i s p e r s i o i i i:i Yalaya with partict11,lr reference to the fly problem in the Came Highlaiid.;. Xedical - --- -- jituri~al o f Xalaya, - 17: 115-L31 (1963).

35. WHO Technical Report Series, No. 441, 1971. (Solid waste disposal and control: rep of a WHO Expert G o m m i t t e e ) , Geiteva. 34 pp.

-, 0 . $H3 Tt'chnicill Rejti)r'; St,r ie.;, S:?. 585, 1976. (Resistaiice of vectors and reservoirs

pesticides: twenty-second report o f the WHO Expert Committee disease to Insecticides), Geneva, pp. 49-53.

. Tec'ni~i:-,il R Series, No. 655, 1980. (ili.sistance of vectors of disease pesticides: fifth report of the WHO Expert Committee on Vector Biology and Contro Geneva, p;., 25-26; 40-51.

W-.. WHO Technical Report Series No. 7 3 7 , 1986. (Resistance of vectors and reservoirs disease to p~sticides: tenth report of the WHO Expert Committee on Vector Biology Cs)ritritl), Ce~evi, 8& pp.

O" dolfc, H . L . , Z L J ~ , W.J. van, Roy, H. Houseflies, the availability of water, diarrhoea1 disc-sss. Bulletin of the World Health Organization, 2: 952-959 (1969).

9cj, tiorld HeaLttr Organization. Chemical methods for the control of arthropod vectors pests of prlblic health importance. Geneva, 1984, 108 pp.

9:. Yamamoto, R.T. & Jcrlsen, E. Ingestion of feeding stimulants and protein by the fern housefly, gusca don~>qtica L. Journal of insect physiology, - 13: 91-98 (1967).

The author wishes tc) express his sincere thanks to colleagues in Denmark and elsewhe fr3m whoa he hai rrcelied personal communications on the subject of the document, e. K. XrevaJ, J.B. Jesperseri, 5.S. OLesen, 0. Skovmand and P. ~strbm, Denmark; Gao Jin-Ya a

V Gong Kun-Yuan, Cllina; V. Rupes, Czechoslovakia; D.B. Pinniger, England; T. Shono a N. M~toyama, Japan; G.P. Georghiou and M.S. Mulla, United States of America.

WHOfv~Cl86.937 page 59

1 X . EVALUATION

A. W e s t i o n n a i r e f o r s e l f - e v a l u a t i o n

( A l l q u e s t i o n s r e l a t e t o t h e common house-f ly , Musca domes t i ca , u n l e s s o t h e r w i s e s t a t e d . S e c t i o n s where t h e answers c a n be found a r e i n d i c a t e d i n b r a c k e t s ) .

L . S t a t e the g e o g r a p h i c a l d i s t r i b u t i o n of t h e house-f ly by c l i m a t i c zones ( t r o p i c a l , s u b t r o p i c a l , t empera te , s u b a r c t i c ) and c o n t i n e n t s (page 5) .............................. .........................................................................................

2 . What i s t h e d i f f e r e n c e i n b reed ing h a b i t s between Musca s o r b e n s and Musca domes t i ca? (page 1 1 ) .............................................................................. .........................................................................................

3. Number of l a r v a l i n s t a r s ? (page 9 ) ..................................................... 4. The d i f f e r e n c e i n behaviour between t h e l a r v a e t h a t a r e ready t o pupate and t h e p rev ious

l a r v a l s t a g e s ? (page 9 ) ................................................................. ......................................................................................... ......................................................................................... 5. The t empera tu re a t which t h e development from egg t o a d u l t i s most r a p i d (optimum

tempera tu re ) : 250 - 30e - 350 - 400 - 45O? (page 8) ..................................... 6. S h o r t e s t l e n g t h of development of egg + l a r v a e + pupae? 2-4-6-8-10-12 days? (page 8 ) . ......................................................................................... 7 . S t a t e 3 main b r e e d i n g s o u r c e s i n r u r a l a r e a s ( a ) .......................................

( b ) .................................. ( c ) ...........................................*.. and i n urban a r e a s ( d ) ................................................................. ( e ) .................................... ( f ) ..................*........................ (pages 11/12, 20-26).

8. S t a t e t h e d i f f e r e n c e i n n i g h t r e s t i n g h a b i t s of h o u s e - f l i e s i n t r o p i c a l and temperate c l i m a t e s (page 1 6 ) ...................................................................... ......................................................................................... ......................................................................................... .........................................................................................

9. S t a t e t h e main d i s e a s e s which f l i e s may t r a n s m i t (pages 19120) ......................... ......................................................................................... ......................................................................................... 3.0. S t a t e a t l e a s t f o u r f a c t o r s t h a t i n f l u e n c e t h e t r a n s m i s s i o n of e n t e r i c d i s e a s e s by f l i e s

(pages 17-19).. .......................................................................... ......................................................................................... ......................................................................................... ......................................................................................... 11. s t a t e t h e most impor tan t methods of environmental s a n i t a t i o n f o r f l y c o n t r o l (pages 20-

28)

( a ) i n r u r a l areas...................................................................e..... ......................................................................................... ( b ) i n urban a r e a s ....................................................................... .........................................................................................

WHO/VBC/86.937 page 60

1 2 . S t a t e two i n s e c t Jevel~pmsn: i n h i b i t u r s w h i c h a r e e f f e c t i v e as b t u u s e f l y l a r v i c i d e s ( p a g e s 28-29) .......................................................................... ......................................................................................... .........................................................................................

13. Which a p p l i c a t i o n is most l i k e l y t o s e l e c t f o r r e s i s t a n c e ? ( p a g e s 29-35) ( a ) Space s p r a y s ( b ) R e s l d u a l s p r a y s ol p o t e n r i a L r r s r i n g p l a c e s c c ) Tox ic b a i t s ( d ) impregna ted c ~ r d s o r s t r ~ p s

L + . S t a t e a r e a s where DDT i s a n r r f e c c i v e i a s e c t l c i d e f o r c o n t r o l u f h o u s e - f l i e s ( p a g e s 37/38) ......................................................................................... ............................... 15. Mention f o u r common p r e d a t o r s o f E ly La rvae < p a g e s 41-44) .........................................................................................

16. h e n c i o n f o u r methods f o r e s t i m a t i n g r e l a t L v e fly d e n s i t y , and s t a t e t h e i r main advan tages and d i s a d v a n t a g e s i page -+;

( a ) ..........................................................eea..e..........e........B.... ..................................................................................... ( b ) ..................................................................................... .....................................................................................

( d ) ..................................................................................... ..............................................*....**............*..*..................

wttO/Vtlc/S6.937 page 61

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