3种植物提取物及其组合对稻田天敌群落的影响

应用生物多样性指数,评价了3种植物乙醇提取物及其组合对稻田主要天敌群落多样性的影响.结果表明,薇甘菊Mikania micrantha Kunth乙醇提取物2.0g·l00mL-1以下及其组合、香泽兰Chromolaena odorata (L.)King & Robinson乙醇提取物2.0g·100mL-1以下及其组合,蜘蛛、捕食性天敌昆虫和寄生性天敌昆虫的多样性指数(H')与均匀度指数(E)较清水对照均有不同程度的提高;薇甘菊乙醇提取物2.0g·100mL-1以上对捕食性天敌昆虫、香泽兰乙醇提取物2.0g·100mL-1以上对蜘蛛和寄生性天敌昆虫均有一定的毒杀作用,且随着浓度的提高和施用次数的增加,其毒杀作用增强;而印楝素(现代苦楝油Melia azedarach L.的提取物)与其他2种植物提取物(0.01g·mL-1)的不同组合均对稻田天敌类群均有较强的毒杀作用.因此建议降低香泽兰乙醇提取物与印楝素的使用浓度或施用次数,以减轻对自然天敌的影响.

Impact of Plant Extracts and Their Combination on the Natural Enemy Community in Paddy Fields

The diversity index was used to evaluate the impact of plant extracts on natural enemy community in rice paddy fields.Results showed when alcohol extracts from Mikania micrantha Kunth or Chromolaena odorata（L.） King Robinson at the concentration lower than 2.0 g·100mL-1 were sprayed,the diversity index （H′） and evenness index（E） of spider,predators and parasitoids all increased compared with water control,indicating that they were safe to these natural enemies.In contrast,the alcohol extracts from M.micrantha and C.odorata at the concentration higher than 2.0 g·100mL-1 had toxic effects on predator,spider and parasitoid to some extent;toxic effects grew steadily with increase in extract concentration and spray times.Azadirachtin,extracts from Melia azedarach L., and their different combination with the alcohol extracts from M.micrantha and C.odorata had strong toxic effects on natural enemy in paddy fields.Therefore,spraying concentration and times of these plant extracts should be reduced to protect natural enemy community.