Effect of High Temperature on Abamectin and Thiamethoxam Tolerance in Bemisia tabaci MEAM1 (Hemiptera: Aleyrodidae).

Simple Summary: Bemisia tabaci (Gennadius) is a worldwide agricultural pest and is one of the most harmful invasive insect pests in the world. The overuse of insecticides has caused B. tabaci to develop high resistance against multiple insecticidal chemicals. It is well recognized that over-expression of cytochrome P450s involved in insecticide detoxification is one common and major mechanism of resistance to various classes of insecticides in insects. In addition to gene duplication and amplification, up-regulation of P450s at the transcriptional level is a common and important mechanism for P450-mediated insecticide resistance. Here, two new CYP450 genes from B. tabaci MEAM1 were cloned, and their expression patterns were studied in response to two different insecticides, high temperature, and their combined effects. The results showed that the insecticide tolerance could be reduced by high temperatures; under combined stress, the mortality of B. tabaci MEAM1 increased. This study is an important addition to the research on insecticide tolerance in B. tabaci and may help to reduce the overreliance on insecticides for B. tabaci control. Bemisia tabaci (Gennadius) is one of the most important invasive species in China, with strong insecticide resistance and thermotolerance. In this study, we investigated the effects of elevated temperature on the tolerance of B. tabaci MEMA1 to abamectin (AB) and thianethixam (TH) insecticides. We firstly cloned two new CYP450 genes from B. tabaci MEAM1, including one CYP6 family gene (BtCYP6k1) and one CYP305 family gene (BtCYP305a1). The expression patterns of the two BtCYP450 genes were compared in response to high-temperature stress and insecticide exposure, and RNAi was then used to demonstrate the role that these two genes play in insecticide tolerance. The results showed that expression of the two BtCYP450 genes could be induced by exposure to elevated temperature or insecticide, but this gene expression could be inhibited to a certain extent when insects were exposed to the combined effects of high temperature and insecticide treatment. For AB treatment, the expression of the two BtCYP450 genes reached the lowest level when insects were exposed to a temperature of 41 °C and treated with AB (combined effects of temperature and insecticide). In contrast, TH treatment showed a general decrease in the expression of the two BtCYP450 genes with exposure to elevated temperatures. These findings suggest that insecticide tolerance in B. tabaci MEAM1 could be mediated by high temperatures. This study provides a prospective method for the more effective application of insecticides for the control of B. tabaci in the field. [ABSTRACT FROM AUTHOR]