The Synergism of Substituted Phenyl N-methylcarbamates by Piperonyl Butoxide1

The toxicity of 40 substituted phenyl N-methylearbamates to the house fly, Musca domestica L., was re-evaluated with piperonyl butoxide as a synergist. There was no correlation between house fly toxicity and fly brain anticholinesterase activity when the carbamate was used alone. In general, the use of piperonyl butoxide with the carbamate increased the toxicity to levels which parallel anticholinesterase activity. An approximately linear relationship between the logarithm of toxicity and cholinesterase inhibition was obtained. The data support previous suggestions that variability in the toxicity of carbamates used alone is due to different detoxication rates in the insect.