Studies on the Toxicity of insecticide Films

Abstract

Experiments on the effect of changes in relative humidity on the toxicity of DDT- and DNC-films to adults of Tribolium castaneum and larvae of Plutella maculipennis are described. With T. castaneum adults the toxicity of both DDT and DNC films is increased at higher relative humidities, but with larvae of P. maculipennis the toxicity of DDT films decreases while that of DNC films increases at higher humidities. Like these experiments the perusal of the literature does not help in deducing any general principle. However, it is possible to collect instances showing that besides the insect and the insecticide, there may be various factors like the range of humidity tested, the strength of the insecticide used, the stage of the insect, etc., which can affect the result of humidity changes.