Inheritance of resistance to imidacloprid and chlorpyrifos in greenhouse whitefly, Trialeurodes vaporariorum

Inheritance of resistance of the greenhouse whitefly, Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae), to imidacloprid and chlorpyrifos was studied. In this study, the Filistan population (FL) and the Fardis population (FR) were used as resistant and susceptible parents, which collected from Varamin and Karaj cities, respectively. The resistance ratios (RR) of FL population obtained for imidacloprid and chlorpyrifos were about 13.62 and 14.91-fold, respectively. LC50 values of chlorpyrifos on F1 (R♂×S♀) and Fʹ1 (R♀×S♂) crosses did not show any significant difference. Therefore, the resistance of T. vaporariorum to chlorpyrifos is autosomal. Also, the values of dominance factor indicated that the resistance of greenhouse whitefly to chlorpyrifos is inherited in incomplete recessive form. In addition, by using the expected mortality of the F2 generation with the generations resulting from crossing, it was determined that the resistance of T. vaporariorum to chlorpyrifos is polygenic. The results obtained from imidacloprid bioassays showed that the resistance of the greenhouse whitefly to this compound is autosomal, incompletely dominant, and polygenic. The present study suggests that according to the knowledge of the inheritance of resistance of T. vaporariorum, it is possible to delay the spread of resistance by using timely, correct, intermittent, and mixed insecticides.