Experimentally induced heat- and cold-shock tolerance in adult Panstrongylus megistus (Burmeister) (Hemiptera, Reduviidae)

Abstract

The survival rate of domestic male and female adult Panstrongylus megistus was studied after sequential heat and cold shocks in order to investigate shock tolerance compared to that previously reported for nymphs. Sequential shocks were such that a milder shock (0 degree C, 5 degrees C, 35 degrees C, or 40 degrees C for 1 h) preceded a severe one (0 degree C or 40 degrees C for 12 h), separated by intervals of 8, 18, 24, and 72 h at 28 degrees C (control temperature). The preliminary thermal shock induced tolerance to the more severe one, although tolerance intensity depended on the initial shock temperature and the interval between treatments. Despite the observed tolerance, the survival rate for insects subjected to both shocks decreased when compared to that of individuals subjected to a single mild shock. When tolerance differed with sex, females showed greater values than males. In contrast to the response detected in nymphs, for which higher heat tolerance values were sustained for intervals of up to 24 h (preliminary shock, 35 degrees C) or even longer (preliminary shock, 40 degrees C) between sequential shocks, significant values were verified in adults only for shock intervals of up to 8 h (preliminary shock, 40 degrees C). While findings for nymphs exhibited considerable cold-shock tolerance under conditions in which preliminary shocks were given at 5 degrees C or 0 degree C and the periods between shocks were up to 72 h long, the adults were shown to be capable of acquiring a substantial tolerance response to a more severe cold shock only when the preliminary shock was given at 0 degree C and shock interval surpassed 18 h. It is assumed that the mechanisms involved in the cellular protection of P. megistus under sequential temperature shocks (heat shock protein action?) may loose effectiveness with insect development.

Changes of nuclear phenotypes inPanstrongylus megistus(Hemiptera, Reduviidae) under different stress conditions

“…This finding agreed with the resistance of fasted specimens of T. in/estans to combined stress factors such as fasting and heavy metals, and enhanced tolerance to sequential cold shocks (MELLO et al 1995;CAMPOS et al 2002). Probably heat-shock proteins preliminary activated by fasting or fasting plus refeeding conditions induced tolerance to a sequential stressor like a short heat shock (WELCH 1993;GARCIA et al 2003), similarly to the effects promoted in P. megistus by sequential heat or cold shocks (GARCIA et al 2002;2003 ). P. megistus is the principal vector of T. cruzi in the eastern, southern and some northeastern states of Brazil (BARBOSA et al 2001).…”

Effect of sequential heat and cold shocks on nuclear phenotypes of the blood-sucking insect, Panstrongylus megistus (Burmeister) (Hemiptera, Reduviidae)

“…Heat shock tolerance has been demonstrated for P. megistus in terms of increased specimen survival and molting rates elicited by sequential heat shocks in comparison with single heat shocks (Garcia et al 2001b). Present results indicate that heat shock tolerance in P. megistus also involves morphological changes at the cellular level.…”

“…Heat-shock tolerance follows a pattern typical of heat shock protein activation (Garcia et al 2001a). Coldshock tolerance also presumably involves heat shock proteins, although consideration of other protective mechanisms has not been eliminated (Garcia et al 2001b).…”

Expression of heat shock proteins in adult honey bee (Apis mellifera L.) workers under hot-arid subtropical ecosystems

“…HSPs are synthesized constitutively in several insects, such as the silk worm, red flour beetle, mosquito species, Drosophila, Reduviid bug and honey bees (Garcia et al, 2003, Elekonich, 2009, Xu et al, 2010, Zhao et al, 2010). The temperature and its exposure time are very crucial for the synthesis of HSPs, which may protect the insects from thermal damage.…”