The research on gonotrophic cycles of the females of the species Tabat/lis sudeticus (Diptera: Tabanidae) was conducted in a region adjacent to the river Sava ...
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Vol. 21, No.2, 113 -II H, 2002
Ekol6gia (Bratislava)
n.ESEARCH OF THE GONOTROPHIC CYCLE OF TI-IE SPECIES Tabanus sudeticus Z c II c r 1842 (DIPTERA: TABANIDAE) IN EASTERN CROATIA /
STJEPAN KRCMAR, PAULA DURBESIC, BRANKO DMITROVIC Department of Biology, Faculty of Education, J.J. Strossmayer University, L. Jagera 9, 31000 Osijek, Croatia Department of Zoology, Faeully of Natural Science, University of Zagreb, Roosevcltov trg 6, 10000 Zagreb, Croatia Medical Faculty, J. J. Strossmayer University, J. Hutlera 4,31000 Osijek, Croatia Abstract Krcmar S., Durbesic P., Dmitrovic 13.: Research of the gonotrophie cycle of the species Tabanlls sudeticus Z e I I e r 1842 (Diptera: Tabanidae) in Eastern Croatia. Ekol6gia (I3ratislava), Vol. 21, No.2, 113-118,2002. The research on gonotrophic cycles of the females of the species Tabat/lis sudeticus (Diptera: Tabanidae) was conducted in a region adjacent to the river Sava in Croatia in the course of 1995. The analysis was performed on 25 specimens. In the analyzed sample' there were 20 anautogene ous specimens in their first gonotrophic cycle. Egg foil icles of anautogeneous females were mos tly in the second and first stage of development. The shrunk cellular remains of follicular epithe lium on egg follicles of the specimens sampled in July show that these females had one oviposition. Key words: diptera, Tabanlls slidetiClIs, gonotrophic cycle, Croatia
Introduction
Horse flies (Tabanidae) have been the object of numerous research works because they are carriers of many diseases which they transfer on humans and on cattle (Foil, 1989). In recent years thorough research works have been conducted on development cycles ofNe arctic and Palaearctic species of horse flies. Of the 520 examined females belonging to 12 species that have been collected on the territory of the then Czechoslovakia, all specimens - except one belonging to the species Chrysops viduatus - were autogeneous in the first gonotrophic cycle (Doskocil, Chvala, 1980). In Germany both autogeneous and anautogeneous specimens were found in the sample including females of25 species. Spe cies Haeptatoma pellucens and Haematopota pluvialis were autogeneous and all other were anautogeneous (Kniepert, 1980, 1983, 1984). In Switzerland, on the sample of 464 females, it was detennined that Hybomitra kaurii, Haematopota pluvialis and Haematopota 113
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/ crassicornis were autogenous species, while the species Taba/1us hrolllius was anautogcneoLis
(Auroi, 1982). It is known that the females of hematophagolls Dirtcra, including horse nics (Taba nidae) in most cases - but not always - lay eggs only after taking a blood meals (Inaoka, 1992). Horse nics of the srecics Tabanus sudeticus. which is dominant in Eastern Croatia, take their blood meals exclusively on the backs of cattle. Specimens of this species are also known as carriers of spiroplasma (tsp), (Le Goff et al., 1991). In this research, we have tried to determine the number of ovipositions through analysis of egg follicles and also to determine whether the species Tabanus sudeticus is autogeneous or anautogeneous in the investigated region adjacent to the river Sava in Eastern Croatia.
Method Females of the species Tabanus sudeticus were sampled by means of a sampling net while taking their blood meals from callie on the stations in the vicinity of the river Sava in Eastern Croatia in June, July and August 1995. Research was performed on the maturation of egg follicles and on the presence of shrunk cellular remains of follicular epithelium according to the Polovodova method (Detinova, 1962). The sampled horse flies were determined according to the key Chvala et al. (1972).
Results
Analysis was performed on the ovarioles in the ovaries of 25 females of the species Ta banus sudeticus (Table 1). In 15 specimens collected in June, egg follicles were in the first, second and third stage of development. In stage I of its development, the oocyte becomes clearly visible in the distal portion of the follicle, whereas seven nurse cells lie in its proxi mal portion. Stage II is characterized by numerous yolk granules around the nucleus in the oocyte protoplasm (Fig. 1). In stage III of its development, the oocyte increases its share within the follicular space from one half to three quarters (Fig. 2). Ovarioles were also analyzed on the sample of 8 specimens collected in July. In 5 of them shrunk cellular rc-
Tab leI. Developmental stages of egg follicles of analyzed females of the species Tabanus sudeticus sampled next to the Sava river in Croatia Developmental stages of egg follicles Months
Analyzed specimens
I
II
III
IV
V
the shrunk cellular remains
June
15
4
10
I
-
-
-
July
8
I
2
-
-
-
5
August
2
-
2
-
-
-
-
Total
25
5
14
I
-
-
5
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Fig. 1. Transverse section of an ovariole of Tabal/us sude/iells. A - follicular epithelium, B- yolk, C - nucleus, 0 .- nurse cells. Haematoxy\in and Eosin, l25x.
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