Life cycle of tortoise tick Hyalomma aegyptium under laboratory conditions

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  • Life cycle of tortoise tick Hyalomma aegyptiumunder laboratory conditions

    Pavel Siroky Jan Erhart Klara J. Petrzelkova Martin Kamler

    Received: 7 February 2011 / Accepted: 5 March 2011 / Published online: 24 March 2011 Springer Science+Business Media B.V. 2011

    Abstract The tortoise tick Hyalomma aegyptium has a typical three-host life-cycle.Whereas its larvae and nymphs are less host-specific feeding on a variety of tetrapods,

    tortoises of the genus Testudo are principal hosts of adults. Ticks retained this trait also inour study under laboratory conditions, while adults were reluctant to feed on mammalian

    hosts. Combination of feeding larvae and nymphs on guinea pigs and feeding of adults on

    Testudo marginata tortoises provided the best results. Feeding period of females was onaverage 25 days (range 1744), whereas males remain after female engorgement on tor-

    toise host. Female pre-oviposition period was 14 days (331), followed by 24 days of

    oviposition (1829). Pre-eclosion and eclosion, both together, takes 31 days (2143).

    Larvae fed 5 days (39), then molted to nymphs after 17 days (1223). Feeding period of

    nymphs lasted 7 days (510), engorged nymphs molted to adults after 24 days (1926).

    Sex ratio of laboratory hatched H. aegyptium was nearly equal (1:1.09). The average

    P. Siroky (&)Department of Biology and Wildlife Diseases, Faculty of Veterinary Hygiene and Ecology, Universityof Veterinary and Pharmaceutical Sciences, Palackeho 1-3, 612 42 Brno, Czech Republice-mail: sirokyp@vfu.cz

    J. ErhartInstitute of Parasitology, Biology Center, Academy of Sciences of the Czech Republic, Branisovska31, 370 05 Ceske Budejovice, Czech Republic

    K. J. PetrzelkovaInstitute of Vertebrate Biology, Academy of Sciences of the Czech Republic, Kvetna 8, 603 65 Brno,Czech Republic

    K. J. PetrzelkovaLiberec Zoo, Masarykova 1347/31, 460 01 Liberec, Czech Republic

    M. KamlerDepartment of Parasitology, Faculty of Veterinary Medicine, University of Veterinary andPharmaceutical Sciences, Palackeho 1-3, 612 42 Brno, Czech Republic

    Present Address:M. KamlerBee Research Institute Dol, Dol 94, 252 66 Libcice nad Vltavou, Czech Republic

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    Exp Appl Acarol (2011) 54:277284DOI 10.1007/s10493-011-9442-8

  • weight of engorged female was 0.95 (0.721.12) g. The average number of laid eggs was

    6,900 (6,5247,532) per female, it was significantly correlated with weight of engorged

    female. Only 2.8% of engorged larvae and 1.8% of engorged nymphs remained un-molted

    and died. Despite the use of natural host species, feeding success of females reached only

    45%. The whole life-cycle was completed within 147 days (98215).

    Keywords Hyalomma aegyptium Testudo Life-cycle Laboratory rearing

    Introduction

    Availability of pathogen-free ticks in sufficient numbers is inevitable condition for any

    experimental study with ticks and tick-borne agents. Laboratory rearing methods were

    developed for many tick species in the past, particularly for model species used in studies

    of tick biology and epidemiology of tick-borne diseases (i.e. Chen et al. 2009; Ghosh and

    Azhahianambi 2007; Krober and Guerin 2007; Liu et al. 2005; Rechav and Fielden 1997;

    Simo et al. 2004; Slovak et al. 2002; Srivastava and Varma 1964; Yeruham et al. 2000). On

    the other hand, little attention was given to tick species being assumed to have lower

    economic importance.

    Hyalomma aegyptium (Linnaeus, 1758) distributed in Mediterranean area from Atlanticcoastland of Morocco through Northern Africa, Balkan countries, Middle East, and Cau-

    casus region to Central Asia, Afghanistan, and Pakistan (Kolonin 1983), belongs to such

    understudied species. H. aegyptium is dominant species among ticks parasitizing tortoisesin western Palaearct (Apanaskevich 2003; Robbins et al. 1998; Siroky et al. 2006;

    Sweatman 1968), possessing typical three-host life cycle. Larvae and nymphs are less host-

    specific infesting tortoises, lizards, birds, small mammals and even men (Apanaskevich

    2004; Kolonin 2004; Vatansever et al. 2008). Nevertheless, tortoises of the genus Testudoare principal hosts of adult ticks. Other hosts (e.g. hares and hedgehogs) are for adult ticks

    reported rarely (Hoogstraal 1956; Hoogstraal and Kaiser 1960).

    Hyalomma aegyptium is known as a vector and definitive host of tortoise-specificapicomplexan blood parasite Hemolivia mauritanica (Sergent et Sergent, 1904). In a frameof our studies on vectorial capability of H. aegyptium we have got high requirement ofpathogen-free ticks (Siroky et al. 2004, 2007, 2010). The laboratory rearing of thousands of

    H. aegyptium ticks provided controlled conditions to collect information about basic traitsof its life-cycle, feeding, and reproduction. These data are summarized in the presented

    paper.

    Materials and methods

    Origin and keeping of ticks

    Tick laboratory breeding colony was established by five consecutively imported engorged

    females of H. aegyptium. Two females were collected in July 2001 from tortoises Testudomarginata Schoepff, 1792 at locality Volos, Eastern Greece (392002700N, 225404900E).Third female was collected in June 2004 from hedgehog Erinaceus concolor Martin, 1838near Areopoli, South of Peloponnesus peninsula, Greece (364001000N, 222205800E). Lasttwo engorged females were collected in April 2005 from tortoises Testudo graeca Lin-naeus, 1758 at locality Qualat Samaan, NW Syria (361905800N, 365004900E). The ticks

    278 Exp Appl Acarol (2011) 54:277284

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  • were kept in cylindrical glass tubes (23 mm in diameter, 70 mm height) filled with strip of

    filter paper, closed with cotton wool pads, and stored in shaded box under 2225C, andrelative humidity (RH) 6085%.

    Host species

    Unsexed outbred guinea pigs having weight 300500 g and originating from a breeding

    facility of Institute of Parasitology Academy of Sciences of the Czech Republic, Ceske

    Budejovice were used as host species for feeding of larvae and nymphs. Adult male and

    5 year old captive bred juvenile tortoises Testudo marginata originating from privatebreeding stock of the first author were used as natural host species for adult ticks. We also

    tried to feed immature tick stages on tortoises and vice versa adult H. aegyptium on guineapigs, but without significant success. Adult ticks were unwilling to feed on guinea pigs. On

    the other hand, it was difficult to safely manage and control feeding of small immature

    stages of ticks on tortoise body.

    Technique of ticks feeding

    One plastic feeding chamber was glued to clipped back of each guinea pig. Afterwards,

    ticks were introduced into this chamber, which was immediately closed with dense nylon

    cloth. Guinea pigs were kept in open enclosure 110 9 85 9 38 cm (length 9 width 9 -

    height) under temperature 2224C, and RH 5070%, fluctuating slightly according toseason, and controlled daily.

    Adult ticks (5 males ? 5 females) were put together with host tortoise into twill sack,

    which was totally closed for 48 h. Then, the sack was opened and position and attachment

    of ticks was controlled. Host tortoises were kept in closed vivarium 100 9 50 9 45 cm

    (l 9 w 9 h) under 1828C and RH 3555%. Position and feeding state of ticks werecontrolled at least once a day.

    Collection of data on life cycle

    We recorded duration of feeding periods of H. aegyptium larvae, nymphs, and females,defined as interval between insertion of ticks into feeding chamber (for premature stages)

    or into twill sack with tortoise (for tick females). Lasting of molting period represents time

    between spontaneous detachments of engorged larvae and nymphs, respectively, and their

    molting to forthcoming life stage. Weight of ten selected engorged females was recorded

    immediately after detachment from host on laboratory scales RADWAG WAS 220/C/2

    (Radwag, Radom, Poland) and rounded with accuracy 10 mg. Period between their

    detachment and appearance of first eggs represents pre-oviposition period. Lasting of

    oviposition and number of eggs laid was recorded for the same ten females. The eggs were

    removed daily from these females. Eggs from the other females were removed in 35 days

    intervals to avoid their repeated disturbing. Behavior of ticks and their movement on hosts

    was also registered daily.

    Data analysis

    To reveal the relationship among duration of feeding periods, weight of engorged females,

    lasting of oviposition and number of eggs laid we performed several Spearmans

    Exp Appl Acarol (2011) 54:277284 279

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  • correlations. Bonferoni corrections (with added mean correlation between variables as a

    parameter) were used for P values (Sankoh et al. 1997). The analyses were performedusing the STATISTICA software (version 8.0, StatSoft, 2008).

    Results

    The duration of H. aegyptium life cycle under laboratory conditions divided into particularlife stages is given in Table 1.

    Feeding of adult ticks

    Feeding females (N = 30) remained usually after attachment on the same place over all

    feeding period. They changed feeding place exceptionally, usually when firstly attached to

    carapace. Females preferred for feeding the inguinal area and places around hind limbs of

    tortoises (66.7%). Four females (13.3%) engorged in area around forelimbs, other one

    (3.3%) on the neck, five females (16.7%) engorged successfully on carapace in seams

    between carapace scutes. Six females (20%) originally attached to carapace seams changed

    place to inguinal and tight area, and then engorged. Comparing to female