植物提取物和常用药剂对蚜虫重要天敌瓢虫孵化、存活和捕食效能的影响

Effect of plant extracts and some biorational insecticides on egg hatch, survival and predation rates of Menochilus sexmaculata (Fabrieius) and Coccinella trasversalis Fabricius:the key natural enemies of cruciferous vegetable aphids in south Chin

为解决目前化学合成杀虫剂长期大量使用所带来的“3R”问题 ,有必要从对人畜无毒或低毒、对害虫天敌安全的植物和其它天然产物中筛选与环境相容性好的物质作为害虫控制的手段。已经从 63种植物中筛选出两种对蔬菜蚜虫有较好控制作用的植物苍耳 Xanthium sibiricum Petr.et Widd.和白蝴蝶Syngonium podophyllum Schott。报道该两种植物乙醇提取物以及几种常用天然源药剂 (鱼藤酮精、机油乳剂和 0 .3%印楝素乳油 )对深圳菜区蚜虫重要天敌瓢虫 (六斑月瓢虫 Menochilussexmaculata( Fabricius)和狭臀瓢虫 Coccinella trasversalis Fabricius)的影响。结果表明 ,两种植物提取物 ( 0 .0 4 g DW/ml)对所测试瓢虫的孵化、存活和捕食效能与对照之间在 0 .0 1或 0 .0 5水平均无显著差异 ,表明两种植物提取物对瓢虫安全、无明显毒性。而鱼藤酮精 ( 80 0× )、机油乳剂 ( 4 0 0× )和 0 .3%印楝素乳油 ( 2 0 0 0× )在所测试的浓度对瓢虫卵的毒性较强 ,瓢虫卵的孵化率明显降低 ,仅有对照瓢虫卵孵化率的 7.74%～ 1 4.31 % ,因此应避免在田间瓢虫大量产卵的季节使用。苍耳和白蝴蝶提取物对蚜虫的重要天敌瓢虫没有负面影响 ,可以考虑作为保护十字花科蔬菜免遭蚜虫危害的植物保护剂配方。

One of the mechanisms that plants have developed to resist the effects of herbivorous pests is the production of secondary metabolites. Recently these metabolites have been considered as potential alternatives to synthetic pesticides because they are natural products that are active against insect pests while being compatible with the environment because of their low-toxicity to humans, livestock and natural enemies. In southern China the problems of resistance, resurgence and residue associated with the use of synthetic insecticides is particularly severe in cruciferous vegetable production. In a previous study the bioactivity of extracts from 63 plant species were screened against Myzus persicae (Sulzer) and Lipaphis erysimi (Kaltenbach) in vegetables. Extracts from Xanthium sibiricum Petr. et Widd. and Syngonium podophyllum Schott were found to be particularly active and in this study we compared the effect of plant extracts from these two species with a range of other biorational insecticides (including rotenone, petroleum spray oil and 0.3% azadirachtin water-in-oil emulsion) on the important predatory coccinellid species Menochilus sexmaculata (Fabrieius) and Coccinella trasversalis Fabricius in the laboratory. There was no significant difference between survival of adults, predation of adults and larvae, hatching of eggs of coccinellids treated with alcohol extracts of X. sibiricum and S. podophyllum and the control groups treated with water. . However, rotenone (800×), petroleum spray oil (400×) and 0.3% azadirachtin water-in-oil emulsion (2000×) did significantly reduce hatchability of the coccinellid eggs, with the hatching rates being 7.74%～14.31% that of control groups. Results indicate that rotenone, petroleum spray oil and azadirachtin should not be used during the reproductive period of the coccinellids. X. sibiricum and S. podophyllum extracts appear to have promising prospects for formulation into natural insecticides against cruciferous vegetable aphids, as they have no adverse effects on predatory coccinellids.