use P450 DNA-based markers of pyrethroid resistance in Anopheles funestus, coupled with extensive in vivo and in vitro functional validation, to demonstrate that the proficient pyrethroids metabolizing P450s, CYP6P9a/-b, are reducing neonicotinoid efficacy in malaria vectors while exacerbating the potency of chlorfenapyr. The gene discussed is CYP2B6; the disease is malaria.