Mb MNPV对不同群体草地贪夜蛾的毒力差异分析

Virulence of MbMNPV to Populations of Spodoptera frugiperda

甘蓝夜蛾核型多角体病毒Mamestra brassicae multiple nucleopolyhedrovirus(MbMNPV)是一种广谱昆虫病毒,近年来已被应用于草地贪夜蛾Spodoptera frugiperda J.E.Smith的防治上,而不同地区的草地贪夜蛾因环境因子的差异导致其对MbMNPV等生物农药的敏感性不同。本研究首先基于COI和Tpi基因对湖南长沙、河南济源、四川成都、广西南宁和辽宁丹东等5个地区的草地贪夜蛾群体进行了生物型鉴定,同时通过饲毒法测定了不同群体草地贪夜蛾幼虫对MbMNPV的敏感性。结果表明,基于COI基因的鉴定结果显示湖南长沙、河南济源和辽宁丹东的草地贪夜蛾均为水稻型,四川成都和广西南宁群体的草地贪夜蛾为水稻型和玉米型的混合群体,而基于Tpi基因的鉴定结果显示5个群体的草地贪夜蛾均为玉米型。5个群体的草地贪夜蛾3龄幼虫在浓度为1×10^(8)PIB/mL和1×10^(7)PIB/mL的MbMNPV处理下7 d校正死亡率均在90%以上,而浓度为1×10^(6)PIB/mL时,湖南长沙、广西南宁和四川成都群体的校正死亡率显著高于辽宁丹东群体。进一步的毒力测定发现,辽宁丹东群体的LC50是湖南长沙群体的4.9倍,相同浓度下的LT50也均高于湖南长沙群体,同时基于Log-rank检验结果也表明在1×10^(5)PIB/mL~1×10^(8)PIB/mL处理下辽宁丹东群体草地贪夜蛾幼虫的平均存活时间显著高于湖南长沙群体。本研究表明,不同地区的草地贪夜蛾群体对MbMNPV敏感性存在差异,辽宁丹东的草地贪夜蛾群体较其他群体对MbMNPV敏感性更低。

Mamestra brassicae multiple nucleopolyhedrovirus(MbMNPV)is a broad-spectrum insect virus,which has been used to control Spodoptera frugiperda J.E.Smith in recent years.However,S.frugiperda populations from different regions have shown varying sensitivity to biological pesticides such as MbMNPV due to environmental factors.In this study,with identification of biotypes of the S.frugiperda populations from Changsha,Hunan(HNCS),Jiyuan,Henan(HNJY),Chengdu,Sichuan(SCCD),Nanning,Guangxi(GXNN),and Dandong,Liaoning(LNDD)by COI and Tpi genes,we determined the sensitivity of S.frugiperda larval populations to MbMNPV by diet method.The identification based on the COI gene showed that the populations of HNCS,LNDD and HNJY were all rice strains and the populations of SCCD and GXNN were mixed corn and rice strain,while the identification based on the Tpi gene showed that all the five populations were corn strains.The mortalities of the five S.frugiperda larval populations were all over 90%with 1×10^(8) PIB/mL and 1×10^(7) PIB/mL of MbMNPV,but with 1×10^(6) PIB/mL of MbMNPV,the mortalities in HNCS,GXNN and SCCD were significantly higher than that in LNDD.The LC50 of LNDD was 4.9 times higher than that of HNCS,and the LT50 and mean survival time of LNDD were higher than those of HNCS at the same concentration of MbMNPV.This study shows that there are differences in sensitivity to MbMNPV among populations of S.frugiperda from different regions,S.frugiperda population in LNDD is less sensitive to MbMNPV than the other populations.