Survival and molting incidence after heat and cold shocks in Panstrongylusmegistus Burmeister

Survival and molting incidence were studied after heat (40 degrees C) and c old (0 degrees C) shocks in specimens of Panstrongylus megistus with the ai m of establishing its response to temperature stress tinder laboratory rear ing conditions and to understand occasional changes in the biological chara cteristics of specimens captured in nature. The response to the thermal sho cks 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 fou nd to be less resistant to the heat shock assay than Triatoma infestans, an other reduviid species. The short cold shock affected survival of P. megist us more than did the heat shock, survival of fully-nourished specimens bein g preferential. The response of adults to the short cold shock was affected by sex, males being generally less resistant. The insect sylvatic habit wa s found to seldom affect the thermal shock response established for specime ns with domestic habit. A decrease in molting frequency and sometimes a slo wdown of the molting rate were found after the short heat and cold shocks, possibly promoted by change in hormonal balance, and differing from pattern s reported for T. infestans. The results indicate that no generalization sh ould be made for different reduviid species in terms of the effects of temp erature shocks.