Life cycle of tortoise tick Hyalomma aegyptium under laboratory conditions

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 in our 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 on average 25days (range 17-44), whereas males remain after female engorgement on tortoise host. Female pre-oviposition period was 14days (3-31), followed by 24days of oviposition (18-29). Pre-eclosion and eclosion, both together, takes 31days (21-43). Larvae fed 5days (3-9), then molted to nymphs after 17days (12-23). Feeding period of nymphs lasted 7days (5-10), engorged nymphs molted to adults after 24days (19-26). Sex ratio of laboratory hatched H. aegyptium was nearly equal (1:1.09). The average weight of engorged female was 0.95 (0.72-1.12)g. The average number of laid eggs was 6,900 (6,524-7,532) 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 147days (98-215).