| Chilo suppressalis(Walker)is one of the most important pests of rice,which seriously affects the quality and yield of rice.Irrational and abuse of insecticides have aggravated not only pest incidence,but also resistant to many insecticides.Zhejiang Province is lowest population area of C.suppressalis,and it is also menas that the area with high tolerance of C.suppressalis.In recent years,chlorantraniliprole,avermectin,and methoxyfenozide have been commonly used in the field for controlling C.suppressalis.The objective of this study is to monitor the above three insecticide resistance aginst different populations of C.suppressalis in Zhejiang Province and clarified the insecticide resistance in different situation.Detoxification enzyme activities were determined for analysis their correlations with resistance levels,and the resistance mechanism was analyzed.Based on the above results,mixing insecticides and the mixture solution of insecticdes with high synergism have been screened on the stem borer was recorded.It can be provided a theoretical basis for delaying the development of resistance to stem borer and control of rice resistant stem borer.The main findings are summarized as follows:1.Insecticide resistance monitoring of C.suppressalis in different populationsThe insecticide resistance levels of chlorantraniliprole,avermectin and methoxyfenozide in Ninghai,Jinhua,Haiyan,Zhapu,Longyou,Wenling,Yueqing,Rui’an,Xiaoshan and Zhuji varietiesagainst different population of C.suppressalis were determined by rice seedling dipping method.The results showed that the difference in the resistance levels of these three insecticides was more obviously in different populations.The Jinhua and Xiaoshan populations have higher resistance to these three insecticides,while the Zhuji,Zhapu and Haiyan populations were relatively lower resistant.In generally,C.suppressalis populations have the highest resistance to chlorantraniliprole,and the resistance ratios(RRs)are between 37.82 and 151.09,reaching high(10.0<RR≤100)to high(RR>100.0)resistance level;the resistance of avermectin is the lowest,and the RRs are between 7.90-30.10,which showed low(5.0<RR ≤10.0)to moderate(10<RR≤100.0)resistance level;the resistance to methoxyfenozide are between 20.41 and 149.60,moderate(10.0<RR<100.0)to high level of resistance(RR>100).2.Determination of detoxification enzyme activity of C.suppressalis in different populationsThe CarE,GSTs and P450 activities in different C.suppressalis populations were determined.And the correlation between these enzyme activities and the resistance level of different populations was analyzed.The results indicated that different populations showed different detoxification enzyme activities.There was no significant correlation between the other two agents and the measurement of three enzyme activities except the resistance to chlorantraniliprole was negative significantly correlated with CarE.This phenomenon might be related to the insecticide use history difference among geographical populations.3.Indoor compound formula screeningIn order to screen out the high efficiency insecticide mixed solution for controlling C.suppressalis,the toxicity of 15 compounding formulas on the Jinhua population of the pest was determined by rice seedling dipping method.The results showed that comparison of he toxicity of single insecticide and three kinds of mixing schemes of spinosad and indoxacarb,avermectin and bisultap,emamectin benzoate and methoxyfenozide have significant synergistic effect.The co-toxicity coefficients(CTCs)of indoxacarb:spinosad at 1:1,1:9,and 9:1 were 403.20,384.44,and 361.30,respectively.The CTC of emamectin benzoate:methoxyfenozide at 1:1,1:9,and 9:1 were 219.28,553.81 and 272.16,respectively.The CTC of avermectin:bisultap at 1:1,1:9,and 9:1 were 330.35,88.00 and 645.85,respectively.In conclusion,this study investigated that the resistance status of the different geographical populations of C.suppressalis was measured by three detoxification enzyme activities in Zhejiang Province in 2018,and analyzed the correlation between the resistance levels and their activities of detoxification enzymes.On the other hand,the screening of mixing insecticides apply for resistance management problem of C.suppressalis.These results provided a scientific basis for the resistance management of C.suppressalis and have guiding significance for production practice. |
