Cytochrome P-450 in insects—V.: Monoterpene induction of cytochrome P-450 and associated monooxygenase activities in the larva of the variegated cutworm Peridroma saucia (Hübner)

Abstract

1. The induction of microsomal cytochrome P-450 and associated polysubstrate monoxygenase activities by natural levels (0.01–0.1%) of the naturally occurring monoterpenes pulegone, menthone and menthol was examined in sixth-instar larvae of the variegated cutworm ( Peridroma saucia Hübner). 2. The monoterpenes increased cytochrome P-450 levels, aldrin and heptachlor epoxidase activity in microsomes from midgut and other tissues of the midsection. 3. NADPH-dependent cytochrome c reductase levels generally were not increased in midgut microsomes and were increased in carcass microsomes by higher doses of the inducers. 4. Induction by any of the monoterpenes increased the size of the Type I (substrate) binding spectra obtained with pulegone, menthone and nerolidol, but not those obtained with menthol. 5. The induction of polysubstrate monooxygenases by these compounds may increase the resistance of the larvae to both host plant allelochemicals and to insecticides in the field.