RESISTANCE TO PLANT ALLELOCHEMICALS IN HELIOTHIS-VIRESCENS (FABRICIUS)

Potential metabolic routes for the resistance of tobacco budworm (TBW) larvae to host plant allelochemicals nicotine, 2-tridecanone and quercetin were explored. Midgut preparations from larvae resistant to nicotine and 2-tridecanone had elevated levels of cytochrome P450 which were associated with significant increases in metabolism for five of six monooxygenase substrates. In quercetin tolerant larvae, metabolism of two monooxygenase substrates was significantly enhanced although no increase in P450 content was observed. Glutathione transferases and esterases did not appear to be involved in the resistance of any of the strains examined. Patterns of substrate oxidations varied between strains and inducing agents, suggesting that different isozymes of P450 are associated with resistance and induction.