Thermal death studies of third-instar Caribbean fruit fly (Diptera: Tephritidae)

Laboratory tests examined mortality of 3rd-instar Caribbean fruit fly, Anastrepha suspensa (Loew), exposed to 40 degrees C in water baths. Larvae chilled to 4 degrees C before treatment had similar percentage survival (94%) as larvae held at ambient temperature (approximate to 25 degrees C) after exposure to 40 degrees C for 10 min. Significant differences for percentage survival were found between larvae exposed for various durations in sealed metal tubes with rearing diet and larvae exposed in fabric-sleeved cylinders with no diet. Submersion of larvae for 2 h in water at approximate to 25 degrees C before treatment in a 40 degrees C water bath for 67 min did not influence survival. When larvae were exposed to 40 degrees C for 67 min in empty tubes (no diet), larval cohorts at low densities (32 +/- 14 larvae per tube) had higher survival (85.8%) than survival (19.4%) of larvae treated at higher densities (361 +/- 155 larvae per tube). Temperature regimes alone did not explain larval mortality. Other factors such as larval density, substrate, and environmental factors could contribute to mortality.