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.