Effect of sequential cold shocks on survival and molting incidence in Panstrongylus megistus (Burmeister) (Hemiptera, Reduviidae).

The survival and molting incidence were studied in the insect, Panstrongylus megistus, following sequential cold shocks in which a milder shock at 0 or 5 degrees C for 1 h preceded a more severe shock (0 degrees C, 12 h). The shocks were separated by intervals of 8, 18, 24, and 72 h at 28 degrees C. The survival rate after sequential shocks was identical to that of unshocked controls. Cold-shock tolerance differed from heat-shock tolerance since the latter varied with the time between shocks and was much more transient. Sequential cold shocks produced a higher molting incidence when the first shock was given at 0 compared to 5 degrees C. This response was more rapid than that to sequential heat shocks. Cold-shock tolerance in P. megistus may involve heat-shock proteins, although other protective mechanisms may also occur concurrently. This is the first report of cold-shock tolerance in a blood-sucking hemipteran. Copyright 2001 Academic Press.