Changes in Critical Temperature During Nymphal and Adult Development in the Rabbit Tick, Haemaphysalis Leporispalustris (Acari: Ixodides: Ixodidae)

Abstract

1. During the developmental period from nymphal to adult engorgement of the rabbit tick, Haemaphysalis leporispalustris critical temperature changed with developmental stage and nutritional state, but was similar in the two sexes. 2. Critical temperature was low in engorged nymphs one day after drop-off (in the range of 36-40°C), increased during the following 15 days (46-47°C), slightly decreased just after ecdysis (42-43°C), remained constant in unfed females for the next 2 months (42-43°C) and then decreased again during engorgement of adult females (from 42-43 to 37-38°C then to 35-36°C). The rates of water loss also changed with the developmental period. 3. The hypothesis that evaporative water loss might initiate the rapid engorgement phase is supported, although not confirmed, by a close correspondence between the host body temperature and the critical temperature of the tick just prior to the rapid engorgement phase.