Short day exposure suppresses water loss rate in the lone star tick Amblyomma americanum and blacklegged tick Ixodes scapularis (Acari: Ixodidae)

摘要

We report that all non-fed stages of the lone star tick Amblyomma americanum and blacklegged tick Ixodes scapularis have reduced water loss by exposure to short days. This reduction in water loss is more pronounced in larvae and nymphs than in adults. Impressive was the rapid response: all non-fed stages could transition quickly, losing water fast (long day), then slow (short day), and back to fast (long day), with only a single day exposure to short or long day conditions. Short days did not improve the tick's dehydration tolerance limit. Ticks under short days were capable of absorbing water vapour, so their ability to rehydrate by water vapour absorption is not inhibited by change in photoperiod. Our conclusion is that a short-day-induced temporary quiescence helps to regulate water loss that applies to any non-fed stage for overwintering. The shallow nature of this quiescence implies that ticks could easily become active at any time and re-enter quiescence.