University of Veterinary Sciences, Department of General Zoology and Parasitology, Budapest. Hungary

Transcription

1 Laboratory marginatus Mikl6s JANISCH -. reanng Sulz. of the tick Dermacentor Dr. R6bert F ARKAS University of Veterinary Sciences, Department of General Zoology and Parasitology, Budapest. Hungary Parasit. htmg "Laboratory rearing of the tick Dermacentor marginatus Sulz." - Janisch, M. - Farkas, R. - Parasit. hung., l:!.: ABSTRACT. Experiences obtained during laboratory rearing of a tick species, which is widespread in Hungary and is of public health and veterinary importance are reported. The females were collected from cattle and placed in an environment of 20-22oC and > 900/0 relative humidity. The developmental stages were monitored from oviposition to the feeding of the adults. The shorte' st duration of development was 83 days. Finally it is stressed that further studies are necessary to better understand the environmental factors regulating the population dynamics of the species, and for mass production of developmental stages of known age for toxicological studies. KEY WORDS. Dermacentor marginatus Sulz., laboratory rearing, complete life cycle. There have been many attempts to rear tick species in the laboratory. Most of such studies are reports on the ontogeny of various species under different conditions of temperature and humidity (BRETT, 1939; GREGSON, 1942~ LOOMIS, KOCH and MOUNT, 1980; KOCH, 1981; etc.). In possession of the knowledge thus obtained several species are reared on a routine basis in order to more thoroughly study the pathogens of diseases transmitted by the ticks (viruses, protozoans) within the arthropods. In vitro study of acaricids also necessitates the mass production of ticks of known age and developmental stage. In this paper we summerize our experiences obtained during laboratory rearing of Dermacentor marginatus Sulzer, This central European species occurs all over Hungary (JANISCH, 1959). In Hungary it is an intermediate host of the pathogen of equine babesiosis, hence it is of veterinary importance (BUZA et ai., 1953). MA TERIAL AND METHOD Sixteen engorged females were collected from grazing cattle in the vicinity of the village of Izs:ik (County B:ics-Kiskun) in the spring of These animals were placed in glass containers lined with several layers of filter paper on the bottom which were kept continuously wet with physiological saline solution. The bottles were closed with fine-rneshed net and placed in an exsiccator where > 90"/0 relative humidity was maintained with help of KH2P04 solution (WINSTON and BATES, 1960). The exsiccator was placed in a shady part of the laboratory. Temperature of the laboratory was continuously recorded during the study with help of a minimum-maximum th,ermometer, the relative humidity of the exsiccator was monitored with an hygromete r. 71

2 The larvae and the nymphs were fed on the ears of leverets in the following manner: the starved developmental forms were placed into net sacks that could be pulled over the ears of the rabbits, and the sack pulled over the shaved ears were fastened with plaster to the base of the ear (Fig. 1). The adults were fed on cattle. The process of egg-deposition and the development of the larvae and nymphs were daily registered with help of stereomicroscope. RESULTS AND DISCUSSION The data for complete life cycle are given in Table 1. Table 1. Data on the development of Dermacentor marginatus Sub. (at c, and 900/0 relative humidity) Developmental stage Shortest time (days) Quiescent phase prior to OViposition 7 Duration of embryonal development 25 Hardening of the cuticle of the larvae 3 Feeding of larvae 4 Molting of larvae 5 Hardening of the cuticle of the nymphs 7 Feeding of nymphs. 5 Molting of nymphs 11 Hardening of the cuticle of the adults 10 Feeding of adults 6 Complete developmental cycle 83 The first females started depositing eggs, which lasted for several days, after a 7 - days period of preoviposition. The bodies of the ticks gradually decreased in size and were finally desiccated, and at the same time large clumps composed of several hundred eggs appeared in front of them (Fig. 2). We observed that the females covered each of the eggs with a substance, presumably for protection and adhesion, by reaching forward with their capitules, and with the "four-lobed" whitish excretory tube situated in the slit between the head and the scutum smeared a quantity of secretion on the eggs (Fig. 3). As from day 13 after the deposition of the eggs the developing larvae were visible in the eggs, the first specimens hatched on day 25. The translucent cuticle of the larvae gradually hardened, and at the same time changed colour to brown. Similarly to other species, the larvae secreted a white substance when ready for commencing feeding (KOHLS, 1937). They fed for 4-5 days on the ears of the rabbits and we found that the ticks which escape d from the sacks that were not properly fastened to the ears, settled on the nearest site of thin cuticle, the eyelids, were they attached themselves Fig. 1: Net sacks pulled over the ears of the rabbits and fastened with plaster. Fig. 2: Dermacentor marginatus females during oviposition. Fig. 3: D. marginatus female while depositing eggs reaches its capitule downward and thus its four-lobed subscutal excretory tube is distended to the vestibulum vaginae (orig. by M. Janisch) (a= scutum, b= palpus, c= glandula subscutalis, d= vestibulum vaginae ). Fig. 4: Nymphs that had escaped from the ne t sack are feeding on the eyelid of the rabbit. 72

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4 3.. 4

5 and started sucking blood (Fig. 4). The fed larvae commenced molting after a quiescent period of 5 days. The hatched nymphs fed for several days after the hardening of their cuticle, and after having been placed back in the containers, the first adults appeared on day 11. A few days prior to molting the nacreous -pigmented scute of the males, or the brown insular pattern of that could be discerned through the nymphal cuticle. The adults fed for 6-8 days after the hardening of the cuticle. The development of D. marginatus is often months in nature. Anyone of the post-embryonal developmental stages may successfully overwinter (HIEPE and RIBBECK, 1982). The duration of ontogeny may substa ntially be shortened in laboratory conditions. According to earlier data the complete development of this species during laboratory rearing occurs in 4.5 months (BABOS, 1964). During our studies, at C and::> 90% relative humidity the complete developmental cycle was over in 83 days. Other thr.ee-host species have been reported to' have different developmental periods, i. e. 71 days for Amblyomma americanum (Linnaeus, 1758) and 96 days for Dermacentor andersoni (Loomis, 1961). There are several causes for the discrepancies in the data, such as species and population characteristics, and the temperature and humidity condition significantly influence the duration of development. D. marginatus is important from public health and veterinary aspects, therefore further laboratory studies are necessary to establish the environmental factors influencing the population dynamics of the species, and to find reliable methods for mass production of developmental stages for toxicological studies. JANISCH, M. - F ARKAS, R.: A Dermacentor marginatus Sulz. kullancsfaj tenyesztese laborat6riumi viszonyok kozott A szerz6k beszamolnak a Magyarorszagon szeles k6rben elterjedt k6z- es allategeszsegtigyi jelent6seggel blr6 kullancsfaj laborat6riumi tenyesztes soran szerzett tapasztalataikr6l. A szarvasmarhakr6l gy(1jtott, szlvott n6stenyeket C-on, ::> 90% relatlv paratartalm~ k6rnyezetben helyeztek el. Petelerakast6l az ut6dnemzedek adultusainak taplalkozasaig k6- vetlek nyomon a fejl6des szakaszait. A legr6videbb fejl6desi id6nek 83 napot kaptak. Befejezestil hangsulyozzak, hogy a faj populaci6-dinamikajat befolyasol6 k6rnyezeti tenyez6k alaposabb megismerese, valamint a toxiko16giai vizsgalatokhoz sztikseges ismert koru fejl6- desi alakok tomeges el6all(tasa tovabbi laborat6riumi vizsgalatokat igenyel. REFERENCES BABOS, S. (1964): Die Zeckenfauna Mitteleuropas. - Akademiai Kiad6, Budapest, Spec. pp BRETT, G.A. (1939): On the period of survival of the egg, larva and first nymph stages of the argasid tick O. moubata Murray at different relative humidities. - Bull. Ent. Res., 30: BUZA, L. - HAJDU, G. - TEMESI, Z. (1953): L6babesiosis el6fordulasa hazankban. - Magy. Allatorv. Lap., ~: GREGSON, J. D. (1942): Laboratory rearing of ticks. - Proc. Ent. Soc. Brit. Columbia, 39:

6 HIEPE. Th. - RIBBECK, R. (1982): Lehrbuch der Parasitologie, Band 4: Veterinarmedizinische Arachno-Entomologie. - VEB. Gustav Fischer Verlag Jena. JANISC H, M. (1959): A hazai kullancsfauna felt~rk~pez~se. - Allatt. Kozl., 47: KOCH, H.G. - MOUNT, G.A. (1980): Mass rearing of lone star ticks. - J.Econ.Ent. 73: KOCH, H.G. (1981): Lone star tick: molting of engorged larvae and nymphs and survival of unfed nymphs at different temperatures and humidities. - The Southwest. Entomol., ~: KOHLS. G. M. (1937): Tick rearing methods with special reference to the Rocky Mountain _ wood tick, Dermacentor andersoni Stiles. In: Culture Methods of Invertebrate Animals. Comstock PubliShing Co., Ithaca, N. Y. LOOMIS, E. C. (1961): Life histories of ticks under laboratory conditions (Acarina: Ixodidae and Argasidae). - J.Parasit., 47: WINSTON, P.H. - BATES, D.H. (1960): Saturated solutions for control of humidity in biological research. - Ecology,!!: Received: 18 July, 1984 JANISCH, M. - Dr. FARKAS, R. University of Veterinary Sciences, Department of General Zoology and Parasitology. Landler JenO u. 2. H-1078 Budapest HUNGARY 74