绿僵菌MaFZ-13对橙带蓝尺蛾幼虫致病力及林间防治效果

【目的】橙带蓝尺蛾Milionia basalis近年来在我国南方地区严重危害罗汉松Podocarpusmacrophyllus和竹柏Podocarpus nagi，扩散蔓延速度快，造成了很大的损失。本研究旨在评估金龟子绿僵菌Metarhizium anisopliae MaFZ-13菌株对橙带蓝尺蛾幼虫的致病力，探寻橙带蓝尺蛾生物防治新资源。【方法】通过绿僵菌MaFZ-13不同浓度(1.0×10⁵~1.0×10⁹孢子/mL)孢子悬浮液接种橙带蓝尺蛾幼虫，运用时间-剂量-死亡率(TDM)模型对生物测定结果进行分析，同时通过林间喷施1.0×10⁸孢子/mL绿僵菌孢子悬浮液进行林间防治效果试验。【结果】橙带蓝尺蛾幼虫累计死亡率随着绿僵菌MaFZ-13孢子悬浮液孢子浓度的增加和接种时间的延长而增大。接种1.0×10⁹孢子/mL孢子悬浮液8 d后以及接种1.0×10⁸孢子/mL孢子悬浮液10 d后，幼虫死亡率均达到100%；接种1.0×10⁷孢子/mL孢子悬浮液15 d后幼虫死亡率为95.6%。应用TDM模型对生测数据进行分析，结果表明所建模型通过Hosmer-Lemeshow拟合异质性检验，并由模型估算出了该菌株对橙带蓝尺蛾幼虫的致死剂量和致死时间。绿僵菌MaFZ-13菌株接种4, 5, 6和7 d后的半致死剂量(LC₅₀)对数估计值分别为7.99, 7.12, 6.46和5.83。以1.0×10⁷, 1.0×10⁸和1.0×10⁹孢子/mL的孢子浓度接种时，绿僵菌MaFZ-13菌株对橙带蓝尺蛾幼虫的LT₅₀值分别为5.19,3.99和2.81 d。林间用1.0×10⁸孢子/mL绿僵菌孢子悬浮液喷洒9 d后橙带蓝尺蛾幼虫死亡率可达到85.8%，防治效果为85.05%。【结论】绿僵菌MaFZ-13对橙带蓝尺蛾幼虫具有较强的致病力，林间防治效果良好，具有较好的应用潜力。

Pathogenicity and field efficacy of Metarhizium anisopliae strain MaFZ-13 againstMilioniabasalis(Lepidoptera: Geometridae) larvae

【Aim】 Milionia basalis is an insect pest causing serious damage to buddhistpine (Podocarpus macrophyllus) and broadleaf podocarpus (Podocarpus nagi) in southern Chinain recent years, and spreads rapidly, causing huge loss. This study aims to search newbiocontrol agent for this pest by evaluating the pathogenicity ofMetarhizium anisopliaestrain MaFZ-13 against M. basalis larvae. 【Methods】M. basalislarvae were inoculatedwith different concentrations (1.0×10⁵-1.0×10⁹conidia/mL) of spore suspension of M.anisopliae strain MaFZ-13, and then the bioassay data were analyzed usingtime-dose-mortality (TDM) model. In the meantime, the field control efficacy against thispest was also tested by spraying the spore suspension of M. anisopliae strain MaFZ-13 atthe concentration of 1.0×10⁸ conidia/mL. 【Results】 The cumulative mortality of M.basalis larvae increased with the spore concentration of M. anisopliae strain MaFZ-13spore suspension and inoculation time. The cumulative mortality of M. basalis larvaereached 100% at 8 d after inoculation with the spore suspension at the concentration of 1.0×10⁹ conidia/mL and 10 d after inoculation with the spore suspension at the concentrationof 1.0×10⁸ conidia/mL, respectively. When inoculated with the spore suspension at theconcentration of 1.0×10⁷ conidia/mL, 95.6% larvae died at 15 d after inoculation. The dataanalysis using TDM model revealed that the constructed model fitted the data well as shownby Hosmer-Lemeshow goodness of fit test, and the values of lethal dose and lethal time ofthis fungal strain against M. basalis larvae were estimated with the model. The logarithmvalues of the estimated LC₅₀ values of M. anisopliae strain MaFZ-13 against M. basalislarvae were 7.99, 7.12, 6.46 and 5.83, respectively, at 4, 5, 6 and 7 d after inoculation.When inoculated with M. anisopliae suspension at the concentrations of 1.0×10⁷, 1.0×10⁸and 1.0×10⁹ spores/mL, the median lethal time (LT₅₀) values of M. anisopliae strain MaFZ-13 against M. basalis larvae were 5.19, 3.99 and 2.81 d, respectively. The spore suspensionof M. anisopliae strain MaFZ-13 at the concentration of 1.0×10⁸ conidia/mL caused 85.8%mortality of M. basalis larvae in the field at 9 d after spraying, with the controlefficacy of 85.05%. 【Conclusion】 M. anisopliae strain MaFZ-13 has high pathogenicity andfield efficacy against M. basalis larvae, with high potential application value.