Toxicity evaluation of botanical insecticides and their mixture against the spiraling whitefly,Aleurodicus dispersus

【背景】螺旋粉虱是新入侵海南省的严重为害经济作物及园林苗木的害虫。目前,植物源杀虫剂因具有高效和环境友好等特性而被广泛用于害虫防治中。【方法】采用喷雾法和药膜接触法分别测定了9种植物性杀虫剂对螺旋粉虱的毒力。【结果】在供试的9种植物性杀虫剂中,除虫菊素和鱼藤酮对螺旋粉虱成虫的毒力最强,24h的LC50分别为2.56和34.15mg·L-1;印楝素和苦瓜叶提取物的毒力次之,LC50分别为158.36和311.02mg·L-1。除虫菊素对螺旋粉虱若虫和卵也有一定的触杀作用,LC50分别为61.42和77.39mg·L-1。将印楝素和鱼藤酮分别与除虫菊素以1:1的比例混合,对螺旋粉虱成虫的毒力表现出明显的增效作用,其共毒系数(CTC)分别为193.11和224.35。【结论与意义】除虫菊素、鱼藤酮、印楝素和苦瓜叶提取物对螺旋粉虱均具有较强的毒性;印楝素或鱼藤酮与除虫菊素(1:1)的混合物不仅能增强触杀效果,而且能延缓害虫抗药性的产生。

Toxicity evaluation of botanical insecticides and their mixture against the spiraling whitefly,Aleurodicus dispersus

Background]Aleurodicus dispersus Russell,a destructive invasive pest was first found in Hainan,China,in April 2006.Botanical insecticides have long been suggested as attractive alternatives to synthetic ones for pest management because of their high potency,efficacy and more eco-friendly nature.Method]The spraying and film contact methods were used to measure the toxicity of nine botanical insecticides and their mixture against A.dispersus.Result]The maximum mortality of adults was recorded for pyrethrum and rotenone with LC50 at 24 h being 2.56 mg·L-1 and 34.15 mg·L-1,respectively.These were followed by azadirachtin (24 h LC50 being 158.36 mg·L-1) and bitter melon leaf extracts (24 h LC50 being 311.02 mg·L-1).Pyrethrum showed significant insecticidal action to the eggs and nymphs of A.dispersus with 24 h LC50 being 77.39 mg·L-1 and 61.42 mg·L-1,respectively.Bioassay results indicated that mixed azadirachtin or rotenone with pyrethrum (1:1) exhibited a significant synergism against A.dispersus,and their cotoxicity coefficient (CTC) were 193.11 and 224.35,respectively.Conclusion and significance]Several of the examined botanical pesticides showed potential to control A.dispersus.The mixture of azadirachtin or rotenone with pyrethrum could not only have synergism but also delay the resistance of A.dispersus.