Pymetrozine-resistant whitefly Bemisia tabaci (Gennadius) populations in China remain susceptible to afidopyropen

Abstract

The whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is one of the most destructive pests in the world because of its serious damage to various crops and rapid development of insecticide resistance. Afidopyropen is a novel pyropene insecticide with high insecticidal activity against sucking insects and has been registered to control whitefly in China since 2019. In this study, 33 field populations of B. tabaci were collected across China between August 2019 and October 2020 and their cryptic species compositions were investigated. The toxicity of afidopyropen to B. tabaci were measured at different times, which was further compared to the toxicity of pymetrozine. The results showed that only Mediterranean (MED) and Middle East-Asia Minor 1 (MEAM1) species were detected in the field populations. The LC50 values of afidopyropen were significantly higher in the first five days, and subsequently became stable at a lower level after day five. The LC50 value of afidopyropen to field whitefly populations ranged from 1.15 to 4.52 mg/L, and the variation in susceptibility was 1.9-fold. The LC50 value of the mixed susceptible population was 2.31 mg/L, which was established as the whitefly susceptible baseline to afidopyropen in China. The resistance to pymetrozine in field populations ranged from 1.8- to 116.6-fold, but no cross-resistance between afidopyropen and pymetrozine was observed. Taken together, afidopyropen exhibited a great insecticidal potency against 33 field populations of B. tabaci in China and it did not show cross-resistance with pymetrozine, suggesting it could be considered as an effective insecticide in the insecticide resistance management (IRM) of B. tabaci.