Toxicological Studies on the Egyptian Cotton Leaf worm, Prodenia litura. VI. Potentiation and Antagonism of Organophosphorus and Carbamate Insecticides

The toxicity of 11 organophosphorus and 2 carbamate insecticides was determined by topical application to 3rd instar larvae of the Egyptian cotton leafworm, Prodenia litura F. Several organophosphorus insecticides were potentiated when pairs were applied jointly. Most of the potentiated pairs contained 1 strong and another weak insecticide. There were also antagonistic pairs as well as other pairs producing only additive effect when jointly applied. Most pairs that showed potentiation by contact showed it also when applied as stomach poisons. Several pairs of 1 organophosphorus and 1 carbamate insecticide, either carbaryl or UC 10854® (m-isopropylphenyl methyl carbamate), were potentiated as well.