Mortality of diamondback moth, Plutella xylostella (L.), larvae treated with insecticides as a function of temperature

Leaf-dip bioassays were conducted at four constant temperatures by using diamondback moth (Plutella xylostella. [L.]) larvae and the two insecticides permethrin and methamidophos at various rates. Predicted LC50 and LC90 values were calculated based on results from the bioassays and used to determine the effect of temperature on the toxicity of the insecticides. Results indicated that permethrin toxicity to the larvae decreases with temperature whereas methamidophos toxicity increases with temperature. We discuss the implications of these results for a management strategy for diamondback moth larvae in the southern United States.