Metabolic resistance to organophosphate insecticides in natural populations of the whiteflyBemisia tabaci(Hemiptera: Aleyrodidae) in Egypt and molecular identification of mitotypes

The whiteflyBemisia tabaci(Gennadius) (Hemiptera: Aleyrodidae) cryptic species has become an important pest of cotton and vegetable crops in Egypt. In this study, resistance to three organophosphate insecticides (OPs), chlorpyrifos-methyl, profenofos and pirimiphos-methyl, and detoxification enzymatic activities of acetylcholinesterase, carboxylesterase, and monooxygenase were evaluated to establish baseline resistance levels forB. tabaciinfesting cotton in seven Egyptian governorates, compared to a susceptible laboratory referenceB. tabacicolony. Resistance to OPs ranged from low-to-moderate or low-to-high, while detoxification enzymatic activities were predominantly governorate-dependent. Phylogenetic analysis of a fragment of the mitochondria cytochrome oxidase I gene (756 bp) identified field-collectedB. tabacias the B mitotype. The results provide baseline OP resistance levels forB. tabacithat will aid in interpreting future monitoring outcomes and enable detection of insecticide resistance fluxes.

Automated summary

This study evaluated resistance levels of the whitefly Bemisia tabaci in Egyptian cotton to three organophosphate insecticides and detoxification enzymatic activities, providing important baseline data for future monitoring. Enzymatic activities varied among governorates, and phylogenetic analysis identified field-collected B. tabaci as the B mitotype.