Indoxacarb biotransformation in the German cockroach.

Area of Science:

• Entomology
• Pest Management
• Insecticide Toxicology

Background:

• Indoxacarb is a widely used insecticide for German cockroach control.
• Understanding its metabolism is vital for effective pest management and resistance monitoring.
• No prior studies detailed indoxacarb's enzymatic biotransformation in German cockroaches.

Purpose of the Study:

• To elucidate the metabolic pathways of indoxacarb in susceptible and resistant German cockroach strains.
• To identify key metabolites and enzymes involved in indoxacarb biotransformation.
• To investigate potential mechanisms of indoxacarb resistance in field populations.

Main Methods:

• Liquid chromatography and high-resolution mass spectrometry were used to analyze indoxacarb metabolism.
• In vitro biotransformation studies utilized NADPH and cytochrome P450 systems.
• Enzyme-inhibiting insecticide synergists (piperonyl butoxide and DEF) were employed in bioassays and in vivo studies.

Main Results:

• Indoxacarb is bioactivated to a toxic metabolite (DCJW) via hydrolysis, similar to other insects.
• Further metabolism yields hydroxylated and ring-opened products, with higher rates in field strains.
• NADPH/cytochrome P450 enzymes are involved in forming hydroxylated and ring-opened metabolites.

Conclusions:

• Metabolic pathways identified contribute to indoxacarb detoxification and bioactivation in German cockroaches.
• Differential metabolism rates in field strains suggest a role in insecticide resistance.
• This research provides a foundation for developing indoxacarb resistance management strategies.