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应用斯氏线虫(Steinernema carpocapsae)的4个品系和异小杆线虫(Heterorhabditis bacteriophora)的3个品系,以滤纸为介质对八字地老虎三龄和五龄幼虫进行致病力测定,以筛选出对八字地老虎寄生效果较好的昆虫病原线虫品系及最佳防治龄期。生物测定结果表明,7个不同昆虫病原线虫品系均对八字地老虎三龄幼虫具有致病力,其中斯氏线虫Sc-2的致死速度最快,侵染24、36和72 h的校正死亡率一直高于其他线虫品系,96 h时校正死亡率达到100%。Sc-2侵染五龄幼虫24、36、72、96和120 h校正死亡率也一直高于其他线虫品系。可以看出Sc-2是对八字地老虎幼虫最敏感的昆虫病原线虫品系。但随着八字地老虎幼虫发育该线虫的致病力减弱,即Sc-2对五龄幼虫的校正死亡率低于三龄幼虫。八字地老虎蛹对昆虫病原线虫7个品系都不敏感,侵染后可促进蛹提前羽化。因此,田间防治八字地老虎时三龄幼虫期效果最好。
Four strains of Steinernema carpocapsae and three strains of Heterorhabditis bacteriophora were used to test the virulence of three-year-old and fifth-instar larvae of tiger on the filter paper, Striped the tiger parasitic effect better insect pathogenic nematode strain and the best age of prevention and treatment. The bioassay results showed that all of the 7 different nematode nematode strains were pathogenic to the third-instar larvae of the tiger, and the mortality of Scirnerella sibiricum Sc-2 was the fastest, and the corrected mortality at 24, 36 and 72 h Consistently higher than other nematode strains, with a corrected mortality rate of 100% at 96 h. The adjusted mortalities at 24, 36, 72, 96 and 120 h of Sc-2 infected fifth instar larvae were also consistently higher than those of other nematode strains. It can be seen that Sc-2 is the most sensitive insect pathogenic nematode strain to the eight-letter tiger larvae. However, the pathogenicity of the nematode was weakened with the development of the tiger larvae. The corrected mortality of Sc-2 to the fifth instar larvae was lower than that of the third instar larvae. Eight characters of the tiger pupa on the insect pathogenic nematode 7 strains are insensitive to infection can promote pupae emergence in advance. Therefore, the field of prevention and control of the tiger when the third instar larvae best.