MARDI Res. Bull., (198? 10, 3: (323-326)

PADDY HUSK ASH AS A GRAIN PROTECTANTAGAINST BEETLES

TEE SZE PENG*

Keywords: Protectant, paddy husk ash, Sitophilus oryzae, Tribolium castaneum, Oryzaephilussurinamensis, Latheticus oryzae, Rhizopertha dominica, wax layer.

RINGKASAN

Kemungkinan menggunakan serbuk abu sekam padi bagi melindungi bijian yang disimpan dari

serangan Sitophilus oryzae, Tribolium castaneum, Oryzaephilus surinamensis, Latheticus oryzae dan

Rhizopertha dominica telah diselidiki. Sebanyak 200 g beras dan padi dicampurkan bersama abu sekam

pada 1.0-2.5% b/b. Kumbang-kumbang dewasa dimasukkan ke dalam bekas-bekas politilin yang

mengandungi adunan beras/padi/abu tadi lalu dimetrikan. Ketahanan lima spesis serangga terhadap abu

sekam padi berdasarkan geraf masa-kematian adalah seperti kadar kian menurun berikut: O. surinamen'

srs ) I. oryzae > R. dominica ) T. castaneum ) S. oryzae. Kepufusan ujian juga menunjukkan

keseluruhan spesis-spesis yang diuji mati selepas seminggu didedahkan kepada bijian yang digaulkan

dengan2.0To b/b abu.

INTRODUCTION

The traditional use of rice husk ash toprotect rice and paddy from insect infestationhas been reported in India and Japan(Gor,os and WesI-sv, 1980. The effec-tiveness of the inert powder to control insectsis attributed to its abrasive and absorptiveproperties (At-pxlNoen et. al., 1944; Espt.ING, 1971). The dust abrade or absorb theepicuticle wax layer of the insects thusdestroying its waterproof barrier and the in-sects die of dessication.

The potential use of these readily avail-able powders as protectants should be con-sidered as an alternative to insecticides whichhave problems of resistance and residue con-tamination of food grain. The present studyis aimed at investigating the use of powderedpaddy husk ash as a protectant against themajor insect pests of stored rice and paddy.

MATERIALS AND METHODS

Paddy husk were ashed at 700oC for 3hrs. in an ovent and ground into fine powder.

The beetles used for the experiments con-

sisted of laboratory reared Sitophilus oryzae(L.) (Fam: Curculionidae), Tribolium casta-neum (Herbst) (Fam: Tenebrionidae), Ory-zaephilus surinamensis (L.) (Fam: Silvani-dae), Latheticus oryzae (Waterhouse) (Fam:

Tenebrionidae), and Rhizopertha dominicaF. (Fam: Bostrichidae). All the speciesstudied were exposed to milled rice except forR. dominica where paddy is used instead. R.dominica is a major pest of stored paddy.

Milled rice and paddy (moisture content12.0 + 0.5%) each weighing 200 g weretreated wi th 1.0, 1.5, 2.0, and 2.5Vo w/w ofpowdered ash. The treated grains were heldin 12 X 15 cm clear polyethylene bags. Tenone-week old adult insects were then intro-duced into each bag and the content heatsealed. For the control, no ash was added tothe grain in the bags. Three replicates werecarried out for each treatment and the con-trol. Observations on insect mortality weretaken daily over a period of 1 week.

*Crop Protection Branch, MARDI, Serdang.tPhoenix oven type MR4-17-8.

323

Sitophilus oryzae

I.jVo wlw1.5% wlw2.Wo wlw2 5 % w l wControl

Tribolium castaneum

3 4 s 6days after exposure

Figure 1. Effect of paddy husk ash (as admixture in packed rice) on adults of Sitophilus oryzae,

Tribolium castaneum and Oryzaephilus surinamensis.

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)H(

H

bo

()k

d

324

Latheticus oryzae

100

80

60

40

20

0

100

80

60

40

20

03 4 5

Days after exposure

Figure 2. EIIect on paddy husk ash (as admixture) on adults ol Latheticus oryzae in packed riceand Rhizopertha dominica in packed paddy.

RESULTS AND DISCUSSION

The effect of powdered paddy husk ashon the five species of stored product beetles isillustrated in Figures I and 2. The suscepti-bility of the five species to husk ash based onthe time-mortality graph is in the descendingorder O. surinamensis 2 L. oryzae ) R.dominica ) T. castaneum ) S. oryzae.For all the species investigated, completeadult mortality was achieved after one week'sexposure in milled rice and paddy treatedwith2.0% w,/w ash. Nltn (1957) studied thewaterproofing layer of some stored grain in-

r .0% wlwH 1 . 5 % w l wA-----d 2.0% wlwH 2 . 5 % w l wF-{ Control

sects in relation to inert dust action. Hefound that the wax layer of S. oryzae is over-laid by a cement layer which explains its leastsusceptibility to the inert dust. Z. castaneumand R. dominica lack the protective cementlayer and the wax layers are exposed. How-ever, the latter has a softer wax which rendersthem more susceptible than those with harderwax. O. surinamensis and L. oryzae arebasically secondary feeders found among thegrain dusts. Their habit of frequent feedingand active burrowing among the dusts cer-tainly subjected them to a greater effect of theash. The ash treatment thus had a more pro-nounced effect on the insect mortalitv withthese two species.

c)

(|)()g

C)

Rhizopertlw dominica

325

Paddy husk is of low economic value in

Malaysia since it is of limited use and since it

is readily available in large quantities as a by-

product of rice mills. The introduction of in-

expensive husk ash as an inert protectant

against insect infestation as part of the tradi-

tional farm storage pratices can be of great

importance as an alternative to the use of

systhetic insecticides, especially in small farm

REFERENCES

Ar-sxa,Nonn, P., KtrcsENER, J.A. and Bnl-coE, H.V.A. (1944). Inert dust insec-ticides. I. Mechanism of action. Ann.appl. Biol. 31(2): 143-149.

EgEI-tNc, W. (1971). Sorptive dust for pestcontro l . Ann. Rev. Ento. 16: 123-158.

stores where protective measures agarnst

stored product pests are often lacking.

ACKNOWLEDGEMENTS

The author wishes to thank Cik Norlaila

Basirun of Crop Potection Branch, MARDI

for laboratory assistance. He also wishes to

thank Dr. Lee Boun Siew, Head of Crop Pro-

tection Branch, MARDI for useful comments

on the manuscript.

GoI-os, P. and WesLpv, D.J. (1980). Theuse of plants and minerals as tradi-tional protectants of stored products.TPI Report G 138, 32PP,

Nntn M.R.G.K. (1957) . S t ruc ture o f water -proofing epicuticular layers in insects inrelation to inert dust action. Indian J.Ento. 19: 37-49.

SUMMARY

The possibility of using powdered paddy husk ash as a stored grain protectant aga\nsI Sitophilus

oryzae, Tribolium castaneum, Oryzaephilus surinamensis, Itttheticus oryzae and Rhizopertha dominica

was investigated. 200 g of milled rice and paddy were mixed with powdered husk ash at1.0-2.570 w/w.

Adult beetles were introduced into the polyethylene packages containing the treated grain and heat-sealed.

The susceptibility of the 5 species based on time-mortality graph was in the descending order O. surina'

mensis > L.oryzae ) R.dominica ) T,castaneum ) S.oryzae. Resul tsalsoindicatethatcomplete

mortality for all species tested was achieved after one week exposure to grain treated with 2.070 w/w ash.

326

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Figure 3. Trichomes on leaf after being fed upon by midges for two days.

Figure 4. Midge lgn,ae after feeding on trichomes. Note the trichomes, stained red, ingut of lan,ue.

428

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florescence development, resulted in a signi-

ficant reduction of leathery pocket disease

(Lrrrl, 1981). Further work is in progress to

determine the relationship of midges and

leathery pocket disease.

REFERENCES

LEGRICE. D.S. & Mann, C.S. (1970). Fru i t

disease control in pineapples. Farming

in South Africa. 46:9-17 .

Ltu, T.K. (1977). Etiology of three pineapple

. '

fruit disease caused by Penicillium funi'cu losum. Ph .D . t hes i s , Un i v . o {

Hau'aii, 123 pp.

ACKNOWLEDGEMENTS

The author is grateful to En. Chan

Thiam Hwo for laboratory assistance and to

Puan Rokiah Sulaiman for t"vping the manu-

script.

Lttvt, W.H. (1980). Leathery pocket and cork

spot of pineaPPle. Info' PaP' No. 3,

MARDI, Jalan Kebun (mimeo.).

Lrv, W.H. (1981). Recent developments in

leathery pocket control. Info. Pap. Nrt.

10, MARDI, Jalan Kebun (mimeo.).

RoHRBAcH. K .C . & PFEIFFER, J .B . (1976 ) .

Fielcl induction of pineapple interfruit-

let corking. leathery pocket and fruit let

core rot uith Penicillium funicul<tsum'Phy ttryt at tut logy 66, 392-395.

SUMMARY

Midge larvae belonging to the genus Do syhelea (Iam. ceratopogonidae) are commonly found in water

that collects in the 'heart' or centre of pineapple plants, and on young developing inflorescences'

Laboratory studies showed that the larvae ieed on the mushroom-shape trichomes which form a protective

layer above the epidermis ol the leaves and tissues o{ the inflorescences. It is suggested that damage to the

trichomes layer by the larvae allows greater accessibility of Penicillium funiculosum into the young

developing fruitlet leading to infection.

429