Heating rate and induced thermotolerance in Mexican fruit fly (Diptera: Tephritidae) larvae, a quarantine pest of citrus and mangoes.

A bioassay and graduated temperature water baths were used to document the induction of thermotolerance in third-instar Mexican fruit fly, Anastrepha ludens (Loew). The 99% lethal time dose for larvae exposed to 44 degrees C core temperatures in artificial fruit is 61.5 min when a slow heating rate (120 min ramp) is applied, but only 41.9 min when a fast heating rate (15 min ramp) is applied. In electrophoretic profiles a heat inducible protein of molecular weight 32 kDa was detected in 76% of the larvae exposed to the slow ramp treatment, but only 42% of the larvae in the fast ramp treatment. Results from this research demonstrate that thermotolerance can be induced under conditions used to commercially disinfest fresh produce and highlight the necessity for specifying heating rates in quarantine treatment schedules.