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. Panstrongylu s megistus, following sequential ci,ld shocks in which a milder shock at 0 or 5 degreesC for 1 h preceded a more severe shock (0 degreesC. 12 h). The shocks were separated by intervals of 8. 18. 24. and 72 h at 28 degreesC. T he survival rate after sequential shocks was identical to that of unshocked controls. Cold-shock tolerance differed from heat-shock tolerance since th e latter varied with the time between shocks and was much more transient. S equential cold shocks produced a higher molting incidence when the first sh ock was given at 0 compared to 5 degreesC. This response was more rapid tha n that to sequential heat shocks. Cold-shock tolerance in P. megistus may i nvolve heat-shock proteins, although other protective mechanisms may also o ccur concurrently. This is the first report of cold-shock tolerance in a bl oodsucking sucking hemipteran. (C) 2001 Academic Press.