Survival and molting incidence were studied after heat (40C) and cold (0C) shocks
in specimens of Panstrongylus megistus with the aim of establishing its response to
temperature stress under laboratory rearing conditions and to understand occasional changes
in the biological characteristics of specimens captured in nature. The response to the thermal
shocks was found to vary as a function of the temperature and duration of the shock,
developmental phase and sex of the specimens, and in certain cases, the insect habit and
nourishment conditions. P. megistus specimens were found to be less resistant to the
heat shock assay than Triatoma infestans, another reduviid species. The short cold
shock affected survival of P. megistus more than did the heat shock, survival of
fully-nourished specimens being preferential. The response of adults to the short cold shock
was affected by sex, males being generally less resistant. The insect sylvatic habit was found to
seldom affect the thermal shock response established for specimens with domestic habit. A
decrease in molting frequency and sometimes a slowdown of the molting rate were found after
the short heat and cold shocks, possibly promoted by change in hormonal balance, and
differing from patterns reported for T. infestans. The results indicate that no
generalization should be made for different reduviid species in terms of the effects of
temperature shocks.
