Comparative mortality responses of two Cook Island fruit fly (Diptera: Tephritidae) species to hot water immersion.
Mortality responses of 2 species of fruit fly, Bactrocera melanotus [B. melanota] and B. xanthodes, to heat treatments were investigated using hot water immersion. The eggs (young or mature), 1st, 2nd, and 3 ages (early-, mid-, and late-aged) of 3rd instars were immersed in hot water at selected temperatures in the range 43-48°C. B. melanota mature eggs were more heat-tolerant than all other life stages of either fruit fly species except B. xanthodes early-aged 3rd instars at 48°C, where the difference was not significant. At temperatures ≤45°C, 1st instars of both fruit fly species were more heat tolerant than 3rd instars (all ages), whereas at 48°C the estimated times for 99% mortality for 1st and 3rd instars were similar. B. xanthodes young eggs were significantly less tolerant to heat than all other life stages of the same species, whereas for B. melanota young eggs were less tolerant to heat than late-aged 3rd instars, 1st instars, or mature eggs. B. melanota eggs were more heat tolerant than B. xanthodes eggs, whereas the reverse was true for larval stages.