Spectral interactions of insecticide synergists with microsomal cytochrome P-450 from insecticide-resistant and susceptible house flies

The spectral interactions of 45 insecticide synergists and related compounds with oxidized and reduced cytochrome P-450 from microsomes of insecticide-resistant and -susceptible house flies were investigated. The type III interaction typical of piperonyl butoxide was the most common spectral interaction for the compounds studied. In addition to this, several other varients of the type III interaction were noted. In general these responses with house fly microsomes were similar to those reported for mammals, although some minor species and strain differences were observed. The cytochrome P-450 from susceptible house flies, although reported previously not to exhibit type I difference spectra with many xenobiotics, was found to elicit this spectral response with several methylenedioxyphenyl compounds.