甘肃省5种昆虫病原线虫对草地贪夜蛾的致病力测定

Pathogenicity of five entomopathogenic nematodes from Gansu Province on Spodoptera frugiperda

探讨甘肃省昆虫病原线虫对草地贪夜蛾(Spodoptera frugiperda)的防治效果。通过室内生物测定研究了甘肃省5种10个昆虫病原线虫品系对草地贪夜蛾2龄幼虫的致病力,并用筛选出的高效品系对预蛹和蛹进行致病力测定。结果表明,夜蛾斯氏线虫(Steinernema feltiae)0663PG和卡森斯氏线虫(Steinernema krussei)0657L对草地贪夜蛾2龄幼虫有较高的致病力。在线虫和2龄幼虫数量比为160∶1时,夜蛾斯氏线虫0663PG和卡森斯氏线虫0657L侵染72 h后,草地贪夜蛾死亡率分别达到100%和80%。草地贪夜蛾预蛹在夜蛾斯氏线虫0663PG的处理下2 d后均可成功化蛹,处理15 d后在数量比为3200∶1时,蛹的羽化率为96.67%。数量比为12800∶1时,夜蛾斯氏线虫0663PG侵染草地贪夜蛾蛹13 d后,蛹的羽化率为93.33%,夜蛾斯氏线虫0663PG对草地贪夜蛾预蛹和蛹的致死率均低于10%。综上可知,夜蛾斯氏线虫0663PG线虫品系对草地贪夜蛾幼虫具有较好的防治效果。草地贪夜蛾预蛹和蛹对昆虫病原线虫不敏感,线虫侵染后对蛹的羽化率和羽化时间没有显著影响(P>0.05)。

This study used a series of bioassays to examine the efficiency of using 5 species and 10 indigenous isolates of entomopathogenic nematodes to control the 2^(nd) instar larvae of Spodoptera frugiperda.The pathogenicity of entomopathogenic nematodes with a high virulence were tested against prepupae and pupae.All isolates,showed infectivity to the 2^(nd) instar S.frugiperda larvae;Steinernema feltiae 0663PG and Steinernema krussei 0657L were particularly effective.After exposing one 2^(nd) instar S.frugiperda larva to 160 S.feltiae 0663PG for 72 h,the mortality rates were 100%for the former.When exposed to 50 S.krussei 0657L,the 2^(nd) instar S.frugiperda larvae had a mortality rate of 80%.The S.frugiperda prepupae pupated successfully after 2 d of being infected with S.feltiae 0663PG.When exposed to 3200 S.feltiae 0663PG for 15 d,S.frugiperda pupae had eclosion rates of 96.67%.However,after exposing one S.frugiperda pupae to 12800 S.feltiae 0663PG for 13 d,S.frugiperda pupa had eclosion rates of 93.33%.The mortality rates of S.frugiperda prepupae and pupae were less than 10%.The results showed that S.feltiae 0663PG has great potential as a biological control for S.frugiperda larvae.The S.frugiperda prepupae and pupae were insensitive to the entomopathogenic nematodes,and infections of the latter had no significant effect(P>0.05)on the rate and time of the emergence of S.frugiperda pupae.