Temperature and humidity effects on the oviposition of Hyalomma aegyptium ticks of different engorgement weights.

Abstract

In Lebanon the land tortoise, Testudo (Pseudotestudo) kleinmanni , is the primary host of Hyalomma (Hyalommasta) aegyptium (L.), while the agamid lizard, Agama stellio , and the Eurasian hedgehog, Erinaceus europaeus , are of secondary significance. Female ticks engorged to a considerably larger size on the tortoise and hedgehog than on the lizard. Females from the different hosts were held under different combinations of temperature and humidity and their weight and egg output were checked daily. Most eggs were deposited between 20° and 35°C; very few were laid at 15°C, and none at all at 40°C. The total number of eggs laid was independent of both temperature and saturation deficit. The maximum rate of egg deposition was reached at 30°C and showed no change up to 35/C. The weight of the engorged ♀ affected the total number of eggs laid, while the number of days over which the oviposition period extended was independent of both weight and temperature. Females kept at 20° to 35°C and weighing less than 254 mg laid no eggs. The average number of eggs laid per ♀ was 5198 while the maximum output by a single ♀ (weighing 1462.8 mg) was 16,427. Desiccation did not abbreviate either the longevity, pre-oviposition or oviposition periods. The pre-oviposition period showed an inverse relationship with temperature, but a similar relationship was not clearly defined by either the oviposition period or total longevity. Some unrecognized factor causing mortality frequently expressed itself without reference to the physical environment during the oviposition period.