Monitoring Of Resistance To Imidacloprid And Thiamethoxam Of Bemisia Tabaci In Xinjiang And Exploitation Of Detection Technology Based On BA-ELISA

Bemisia(abaci is a serious agricultural pest in the world that is known as a "super pest".Under the management strategy of chemical control as the main means,the unreasonable use of insecticides inevitably leads to the resistance of B.tabaci to various insecticides.Due to the excessive use of neonicotinoids including imidacloprid and thiamethoxam for controling B.tabaci,the resistance to neonicotinoids has developed worldwide over the years.The populations of B.tabaci in Xinjiang also developed resistance to imidacloprid and thiamethoxam based on our research group’s preliminary investigations.The resistance mechanisms are different among different geographical populations.The resistance mechanism to neonicotinoids of B.tabaci in Xinjiang is still unclear.In this study,the imidacloprid and thiamethoxam resistance levels of different populations of B.tabaci in Xinjiang were determined by adult leaf dip method.The expression of 18 cytochrome P450 genes related to neonicotinoid resistance was analyzed by real-time fluorescence quantitative PCR.Finally,based on the preliminary work of our research group,a technique to detect resistance of B.tabaci field populations based on BA-ELISA was developed with the polyclonal antibody of CYP4G68.The results will provide technical support for clarifying the resistance level and development trend of the insect to neonicotinoids and provide scientific guidance for the establishing of resistance management methods and strategies.The main findings of this paper are summarized as follows:1.Resistance to imidacloprid and thiamethoxam of field populations of Bemisia tabaci in XinjiangThe monitoring and detection of pest resistance is an important basis for the development of resistance management.In this study,the resistance levels to imidacloprid and thiamethoxam of five B.tabaci populations collected from Yining(YN),Turpan(TP1,TP2),Hetian(HT)and Shache(SC)in Xinjiang were evaluated by adult leaf-dip bioassay method to provide a scientific basis for efficient control of B.tabaci.The results showed that the populations had developed moderate to high levels of resistance to imidacloprid in Xinjiang.TP1 population had a high level of resistance to imidacloprid with a resistance ratio of 46.07 fold.TP2,SC,HT and YN populations developed moderate level of resistance to imidacloprid with resistance ratio of 11.53,15.62,12.26 and 14.06 fold respectively.A Low level of resistance to thiamethoxam was found only in the HT population.2.Expression analysis of P450 gene in Bemisia tabaci from XinjiangMany studies demonstrated that the resistance to neonicotinoids of insects was due to the enhanced detoxification caused by overexpression of cytochrome P450 genes,but the resistance molecular mechanisms in different geographical populations or strains are different.In this study,real-time fluorescent quantitative PCR(qPCR)was used to quantitatively measured the expression of 18 P450 genes,and to verify whether these genes are involved in neonicotinoids resistance of the field populations of B.tabaci in Xinjiang.The results showed that CYP6CM1,CYP4G68,CYP6DZ7,CYP303A1-like and CYP6DZ4 in the TP1 resistant population overexpressed,which may be one of the mechanisms of resistance to imidacloprid of B.tabaci in Xinjiang.3.Rapid detection of resistance to Xinjiang whitefly based on BA-ELISAAfter verifying the relationship between CYP4G68 overexpression and resistance in B.tabaci populations in Xinjiang,this study established a rapid detection of resistance to imidacloprid of B.tabaci in Xinjiang.This technique was established by an ELISA method based on the strong affinity of avidin(Avidin)and biotin(Biotin)with the polyclonal antibodies of CYP4G68 to detect the resistance levels of imidacloprid in Xinjiang populations.The results showed that the color reaction of susceptible strain(NJ-S)was the lightest,while the those of the field populations were darker compared to NJ-S.The relative contents of CYP4G68 protein in TP1,SC,YN,TP2 and HT were 23.5,16.0,15.3,13.3 and 6.7 times of that in NJ-S,respectively.The method is simple and sensitive,which is suitable for rapid detection of resistance level in field populations of B.tabaci.