The Fate of Dieldrin in Insects1

Abstract

Under normal physiological conditions the rates of penetration of dieldrin into S- and into R-flies, Musca domestica L., are similar, but in S-flies this rate becomes reduced coincident with the onset of symptoms of excitation. At the same time, the haemolymph of dieldrin-intoxicated flies becomes very much dehydrated and the intestines are swollen with fluid, a phenomenon also occurring with insecticides not related to dieldrin. Translocation of sublethal amounts of dieldrin via the legs to other body parts is similar in S- and R-flies. After a limited period of tarsal exposure to the toxicant, a concentration equilibrium is reached in the body within 2–3 hr, the final distribution then being approximately: legs 5%, head 9%, thorax 22%, wings 1%, and abdomen 63%. The insecticide is less concentrated in the tissues of thorax and legs than in the head and abdomen, but there is also no difference between S- and R-flies in this respect. House flies converted only 10% of a sublethal dose into more hydrophilic and presumably nontoxic material in 24 hours; with Aedes aegypti (L.) larvae this conversion is even less, under 5% in 3 days. There were no significant differences between the 2 strains in the rate of conversion.