Geographical and interspecific variation in susceptibility of three common thrips species to the insecticide, spinetoram

Abstract

Different species of thrips can occur in the same location and on the same plant. However, variation among dominant thrips species in their susceptibility to insecticide remains unclear. In this study, we evaluated the susceptibility of Frankliniella occidentalis, Thrips palmi and Frankliniella intonsa, three common thrips on vegetables, to spinetoram, from 12 geographical areas across China. Thrips palmi showed the lowest susceptibility to spinetoram (LC50 ranged from 0.1192 to 117.6707 mg L−1), while F. intonsa showed the highest susceptibility (LC50 ranged from 0.0044 to 0.6476 mg L−1). Field-evolved resistance to spinetoram was found for T. palmi and F. occidentalis, resulting in 987.17-fold and 323.77-fold differences in toxicity within each of these species, respectively. The Shouguang populations of T. palmi and F. occidentalis had the highest overall levels of resistance, with LC50 values of 117.6707 mg L−1 and 11.4290 mg L−1, respectively. Levels of susceptibility in southern populations of F. intonsa were low compared to northern populations of this species in China. In conclusion, our study highlighted variation in susceptibility of thrips to spinetoram, both among species and among geographical areas. The results should help the implementation of management tactics, and they provide insights into the displacement of thrips species in fields.