The Effects of Temperature and Stage of Life Cycle upon the Toxicity and Metabolism of DDT in the House Fly1

Abstract

Negative temperature coefficients were shown to hold for DDT-resistant and susceptible houseflies in the range of 15[degree] to 35[degree]C. At the higher temperature, resistant flies were affected faster than susceptible flies. The converse was true at the lower temperature. Chemical analysis for DDT and DDE showed that with increase in temperature the change in DDT detoxification rate exceeded the change in absorption rate. At 35[degree]C, DDT metabolism was especially high within the 1st. few hrs. after treatment in the resistant flies. Thus, if an insect lived for a few hrs. at the higher temperature it had an increasing chance of survival. Additional studies on the toxic effect of DDT inclusion in larval diets of DDT-resistant and -susceptible flies at 2000 ppm and 25 ppm, respectively, produced 30% adult mortality in each strain. Internal DDT recovered from each strain of adult flies was less than the amounts required to kill the adult flies by tropical application, but that remaining in the resistant ones was several times greater than that needed to kill susceptible flies.