Engorged nymphs act as a conditioning stage to protect adult American dog ticks and lone star ticks (Acari: Ixodidae) against heat stress

To correlate proper development and survival with moulting in hot summers for adults of the American dog tick Dermacentor variabilis and the lone star tick Amblyomma americanum, the maximum heat shock response was determined for engorged nymphs. An impressive ability to moult successfully with near complete adult survival occurred with 1-hour heat shock as high as 46°C for both species. Heat shock exposures at and above 48°C were detrimental, disrupting regular life history pattern by extending the crawling phase and severely reducing the number of adults that emerged. Amblyomma americanum was characterized by completion of adult development from engorged nymphs, greater adult yield, and enhanced adult survival in response to short-term heat exposure up to 50°C for engorged nymphs and 54°C for adult females. Both species featured the improved ability to recover from heat-induced injury as adults following prior exposure to heat at an ecologically relevant temperature (32oC) as an engorged nymph. Capacity ...