Transmission of Dieldrin from Insects to their Progeny

Abstract

ABSORPTION of small quantities of chlorinated hydrocarbon insecticides affects the reproductive capacity of several species of insects. Egg production may be increased^1,2, or the insect may be so affected that egg formation is prevented³. When a sub-lethal dose of aldrin or dieldrin (1 µg) was applied to the desert locust, Schistocerca gregaria, the average number of egg pods produced per female was not less than that produced by untreated females, and the eggs were viable⁴. When the effect of flight on the toxicity of dieldrin to adult S. gregaria was being studied, it was noted that first instar hoppers (nymphs) from one or two egg pods laid by females treated with 4 µg dieldrin/g body weight showed symptoms typical of dieldrin poisoning and died shortly after hatching, suggesting that the insecticide had been translocated to the eggs, and that the quantity present in the hoppers was lethal. Further experiments were therefore carried out in which known quantities of dieldrin were applied to adult insects of three species, in order to observe the effects on the progeny of those that survived.