Experimentally induced heat-shock tolerance in Panstrongylus megistus (Hemiptera : Reduviidae)

The survival and molting incidence of fifth-instar nymphs of Panstrongylus megistus (Burmeister, 1835), a vector of Chagas; disease, were investigated following sequential heat shocks in which a mild shock (35 or 40 degreesC, 1 h) preceded a more drastic one (40 degreesC, 12 h). The shocks were sepa rated by 8-, 18- 24-, or 72-h periods at 28 degreesC. The heat-shock tolera nce response was more effective when the first shock was given at 40 degree sC. When the period between shocks was 18 h, the tolerance to sequential sh ocks tin terms of specimen survival) weakened, which suggested a transient control of the process that enables the organism to circumvent the unfavora ble effects of severe shock. In tel ms of molting incidence, the heat-shock tolerance was only demonstrated when the period between the first shuck at 40 degreesC for 1 h and the second shock at 40 degreesC for 12 h was great er than or equal to 24 h. These results are the first to demonstrate the in duction of heat-shock tolerance in a blood-sucking hemipteran.