[Parthenogenetic generations of Helicometra fasciata Rud., 1819 (Trematoda: Opecoelidae) in the Black Sea molluscs Gibbula adriatica].
Morphology of the Helicometra fasciata Rud., 1819 parthenogenetic generation from the Black Sea gastropods Gibbula adriatica (Phil.) was studied for the first time. Data on seasonal dynamics of the hemipopulation of daughter sporocysts are given. Daughter sporocysts of H. fasciata infest 10 +/- 0.2 % of G. adriatica (mainly specimens of larger size and elder age classes). As a rule, local microhemipopulations of daughter sporocysts castrate mollusc hosts. Reproduction of H. fasciata daughter sporocysts is asynchronous: daughter sporocysts born specimens of next sporocyst generation during autumn and winter, and then they begin producing cercaria. In winter development of the cercaria embryo is blocked. Second change of the character of the each sporocyst' posterity is impossible because of the annual life cycle of G. adriatica. Endogenous agglomeration of the H. fasciata daughter sporocysts is extremely little: individuals of next sporocyst generation develop from no more than 2 % of embryonic balls. Energy resources of the mollusc host are used by the H. fasciata daughter sporocysts mainly for producing cercaria; this fact can be interpreted as an adaptation of H. fasciata to using medium-sized, short-living mollusc hosts.
Korniĭchuk
Iu M
IuM
D000818:Animals; D006790:Host-Parasite Interactions; D008974:Mollusca / Q000469:parasitology*; D009792:Oceans and Seas; D033661:Oocysts / Q000166:cytology; D010312:Parthenogenesis; D011156:Population Density; D012426:Russia; D012621:Seasons; D014200:Trematoda / Q000033:anatomy & histology / Q000302:isolation & purification / Q000502:physiology*