生防菌爪哇棒束孢对斜纹夜蛾的防效与安全性评价

Control effects of biocontrol strain Isaria javanica on Spodoptera litura(Fabricius)and evaluation safety

【目的】明确生防菌爪哇棒束孢对斜纹夜蛾的防控效果与安全性,为高效绿色防控斜纹夜蛾提供科学依据。【方法】采用浸叶法测定爪哇棒束孢对斜纹夜蛾的室内毒力;采用喷雾法测定200亿孢子/克爪哇棒束孢可湿性粉剂对斜纹夜蛾的田间控制效果;通过药膜法和喷雾法分别评价200亿孢子/克爪哇棒束孢可湿性粉剂对黑卵蜂和甘蓝的安全性。【结果】室内毒力测定结果表明,爪哇棒束孢对斜纹夜蛾3龄幼虫具有较强的毒杀作用,幼虫取食经1.00×10^(7)孢子/mL爪哇棒束孢处理的甘蓝叶片48 h后死亡率达86.96%。田间防治效果试验结果表明,甘蓝田喷施900、1125和1350 g/ha浓度的200亿孢子/克爪哇棒束孢可湿性粉剂10 d后对斜纹夜蛾的防治效果分别为73.08%、82.77%和83.69%。安全性评价结果表明,200亿孢子/克爪哇棒束孢可湿性粉剂对黑卵蜂48 h的致死中浓度(LC_(50))为2.11×10^(8)孢子/mL,对黑卵蜂安全系数为5.27(t>5.00),为低风险性生物农药;200亿孢子/克爪哇棒束孢可湿性粉剂对供试3种甘蓝品种生长速率抑制率均在10.00%以下,且无变色、坏死、萎蔫及畸形等任何可见药害症状。【结论】爪哇棒束孢对斜纹夜蛾3龄幼虫具有较强的毒杀作用,可作为防治斜纹夜蛾有效且安全的生物农药使用。建议在甘蓝斜纹夜蛾低龄幼虫盛发期使用200亿孢子/克爪哇棒束孢可湿性粉剂1125~1350 g/ha进行防治。

【Objective】To evaluate the effects of prevention and control on Spodoptera litura(Fabricius)and the safety of Isaria javanica biocontrol strain and to provide scientific basis for its extensive application.【Method】The indoor toxicity of I.javanica to S.litura was tested with leaf immersion method.Field control effects of 2.0×10^(10) conidia/mL I.javanica WP to S.litura were carried out using the spray method.To evaluate the safety of 2.0×10^(10) conidia/mL I.javanica WP on Telenomus remus and Brassica oleracea var.capitata L.were carried out using the drug film method and the spray method,respectively.【Result】The results showed that I.javanica had a strong toxicity to the 3rd instar larvae of S.litura.The mortality rate of larvae fed on B.oleracea leaves treated with 1.00×10^(7) conidia/mL I.javanica for 48 h reached86.96%.The results of control effects showed that after spraying 2.0×10^(10) conidia/mL I.javanica WP at 900,1125 and 1350 g/ha concentrations for 10 d,the control effects on S.litura were 73.08%,82.77%and 83.69%,respectively.The results of safety evaluation showed that the medial lethal concentration(LC_(50))of 2.0×10^(10) conidia/mL I.javanica WP for T.remus was 2.11×10^(8) conidia/mL(48 h).The safety coefficient to T.remus was 5.27(t>5),which was a low risk biological pesticide.The inhibition rate of 2.0×10^(10) conidia/mL I.javanica WP on the growth rate of the three cabbage varieties was less than 10.00%,and there were no visible symptoms of discoloration,necrosis,wilting,deformity,etc.【Conclusion】I.javanica has strong toxic effect on 3rd instar larvea of S.litura,can be used as an effective and safe biological pesticide for the control of S.litura.It is suggested that 1125-1350 g/ha 2.0×10^(10) conidia/mL I.javanica WP can be used at occurrence period of S.litura larvea on cabbage to control the damage.