Mechanisms and crossresistance of imidacloprid resistance in Frankliniella occidentalis
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Key Words：Frankliniella occidentalis, crossresistance, carboxylesterase, glutathione Stransferase
Abstract： In order to better understand the risk of imidacloprid resistance in Frankliniella occidentalis (Pergande), crossresistance and resistance (synergists and enzyme activity) of this pesticide were investigated. After 35 generations’ selections, the selection populations obtained 2126\| fold resistance to imidacloprid. Imidacloprid had medium levels of crossresistance to abamectin and emamectin benzoate, and had low levels of crossresistance to cyhalothrin, methomyl and chlorpyrifos. The synergists s,s,stributyl phosphorotrithioate(DEF), triphenyl phosphate(TPP) and diethyl maleate (DEM) showed significant synergism (SR50,DEF=638, P<0005; SR50,TPP=552，P<0005; SR50,DEM=160，P<0005) with regard to the toxicity of imidacloprid in the resistant population (BK). In vitro assays of enzyme activities showed significantly increased activity of carboxylesterase (506
\|fold) and glutathione Stransferases (163\|fold) in the resistant population (BK), indicating that enhanced detoxification is responsible for imidacloprid resistance in F. occidentalis.