Physiological Factors Influencing the Toxicity of Carbamate Insecticides to Insects1

The toxicity of 6 carbamate insecticides, alone and synergized with several methylenedioxyphenyl synergists, has been evaluated against the housefly, Musca domestica L., the honey bee, Apis mellijera L.; and the German cockroach, Blattella germanica (L.). The topical LD50 values of the carbamates were markedly affected by the age and sex of the house fly and cockroach, but the differences were almost completely abolished by synergism with piperonyl butoxide, sesamex, and methylene-dioxynaphthalene. The variations in the toxicity of the carbamates to the house fly and German cockroach were well correlated with the titre of soluble phenolases in the various life stages, sexes, and in adults of different ages. However, the honey bee is extremely susceptible to these carbamate insecticides, and little synergism occurs with the methylenedioxyphenyl compounds. In the honey bee only a very low titre of phenolase could be demonstrated.