昆虫病原线虫对小地老虎的致病力测定及防治效果

Virulence and control effect of entomopathogenic nematodes against Agrotis ypsilon( Rottemberg)

为探讨应用昆虫病原线虫防治小地老虎技术的可行性,采用培养皿滤纸法比较9个品系的昆虫病原线虫对小地老虎幼虫的致病力,同时通过盆栽试验验证了斯氏线虫属小卷蛾斯氏线虫Steinernema carpocapsae NC116品系、芫菁夜蛾斯氏线虫S.feltiae SF-SN品系和异小杆线虫属嗜菌异小杆线虫Heterorhabditis bacteriphora H06品系的保苗效果和防治效果,并测定了苦参碱与NC116品系混用对小地老虎3龄幼虫的联合作用效果。结果表明,NC116品系对小地老虎3龄幼虫致病力最高,其对3龄、4龄和5龄的LD50分别为2.4、7.5、和31.2条/头,表明随小地老虎幼虫龄期递增,其致病力下降。盆栽玉米苗上分别施用线虫100~200条/头时,对玉米保苗效果及对小地老虎3龄幼虫的控制效果依次为NC116】H06】SF-SN。0.8 mg/L苦参碱和NC116品系混用后,可使小地老虎3龄幼虫死亡率提高109.89%,二者表现增效作用。

To evaluate the potential control effects of nine entomopathogenic nematodes( EPN) strains against Agrotis ypsilon Rottemberg larvae,the filter paper culture method was used to determine their pathogenicity against the larvae of A. ypsilon under laboratory conditions. Protective effects upon seedlings and control efficiency of three EPN strains( Steinernema carpocapsae NC116,S. feltiae SF-SN and Heterorhabditis bacteriphora H06) were also studied by pot experiments. Meanwhile,the combined effects of nematodes strain NC116 and different concentrations of matrine to the third instar larvae were determined. The results showed that strain NC116 had the highest pathogenicity to the third instar larvae of A. ypsilon,and their pathogenicity decreased as the larval instar increased: strain NC116 LD50 values to the third,fourth and fifth instar larvae were 2. 4,7. 5,and 31. 2 IJs / larva,respectively. Pot experiments showed that the protective effects for seedlings and the control efficacy at the dosage of 100- 200 IJs / larva were in the following order: NC116 > H06 > SF-SN. Mortality of A. ypsilon was raised by 109. 89% under the mixed application of 0. 8 mg / L matrine and nematode strain NC116,which showed a synergistic interaction.