Abstract: Although cytochrome P450s have been well known to play crucial roles in insecticide resistance in insects, the mechanisms of P450-based metabolic resistance have not been fully characterized at the molecular level. Thanks to the development of genomics and biochemical techniques, rapid advances in the studies on the mechanisms of P450-mediated insecticide resistance have been achieved in recent years. This review attempts to summarize the current understandings in this field. P450-mediated resistance is a very common mechanism for almost all types of insecticides, and a single P450 enzyme may confer cross-resistance to different classes of pesticides. Variable genetic basis of resistance has been documented between populations resistant to the same insecticide due to multiple P450 options for evolving resistance. P450-mediated resistance may be due to either increased enzyme production (via enhanced transcription and/or gene duplication and amplification), or a change in structural gene itself that may alter the catalytic properties of the enzyme (caused by point mutations), or gene recombination of two closely linked genes that creates a chimeric enzyme with a novel ability. Constitutive transcriptional overexpression of resistance-associated P450 can be caused by cis- or/and trans-acting factors that have not been well understood. These findings suggest that mechanisms underlying P450-mediated insecticide resistance are diverse and complicated, and resistance monitoring and management should be customized for specific populations in a dynamic context.

Key words: Insect, cytochrome P450, insecticide, insecticide resistance, molecular mechanism, resistance management