棉铃虫食性杂，寄主广，为害严重又对现有农药易产生抗药性，为有效防控其对作物的为害，本文通过室内毒力测定研究了甘南草原有毒植物黄帚橐吾（Ligularia virgaurea ）乙醇提取物对棉铃虫幼虫的农药生物活性，结果表明：黄帚橐吾乙醇提取物对棉铃虫2～3龄幼虫有很强的拒食活性，拒食中浓度（AFC50）为2．59 mg／mL。当提取物浓度为10．00 mg／mL 时，拒食率可达95％以上；触杀和胃毒活性也较强，致死中浓度（LC50）在3．00 mg／mL 左右，浓度为10．00 mg／mL 时，校正死亡率均可达80％以上，而且3种作用的活性强度随浓度增大而增强。杀卵和熏蒸活性相对较弱，但浓度大于10．00 mg／mL 时也有比较明显的杀灭活性。本研究结果证明黄帚橐吾乙醇提取物可以有效防控棉铃虫幼虫的危害，为黄帚橐吾类农药的开发和棉铃虫的有效防治提供了依据和有效途径。%Helicoverpa armigera Hübner is a major Lepidoptera pest on various crops in China,and it can develop easily pesticide resistance.Ligularia virgaurea (Maxim.)Mattf.is a kind of poisonous plant growing in the grass-land of Gannan Tibetan autonomous prefecture.In order to prevent and control H .armigera effectively,the bio-activity of the ethanol extracts of L .virgaurea against H .armigera was investigated in laboratory.The results showed that the extracts of L .virgaurea had strong antifeedant activity against the 2nd-3rd instars of H .armig-era with the AFC50 value of 2.59 mg/mL.Once the concentration of the extracts increased to 10.00 mg/mL,the antifeedant rate could reach to more than 95%.The extracts also demonstrated good contact toxicity and stomach toxicity activity,with LC50 value of all above 3.00 mg/mL.The corrected mortality was above 80% when the concentration of the extracts was 10.00 mg/mL.The higher the concentration,the stronger the activity.The ex-tracts had only weak ovicidal and fumigation activities,but the activity was obvious at the concentration of more than 10.00 mg/mL.These results demonstrated that the ethanol extracts of L .virgaurea could effectively control the harm of of H .armigera larvae,which provided a scientific basis for further development of new pesticides with L .virgaurea for H .armigera control.
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