INSETICIDAL OILS FROM AMAZON PLANTS IN CONTROL OF FALL ARMYWORM

ABSTRACT The potential insecticidal of oils from southwestern Amazon plants against Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae) was investigated. Initial bioassays were performed with undiluted oils from 11 plant species. The efficacy of the oils was evaluated against eggs and third -instar caterpillars of S. frugiperda. The oils of Copaifera sp. (Leguminosae), Orbignya phalerata (Arecaceae), and Carapa guianensis (Meliaceae) displayed a high efficacy against the caterpillars and were used in subsequent concentration-response bioassays, at concentrations established through preliminary tests. The highest nonlethal concentrations of oils and the lowest lethal concentrations were calculated. A completely randomized design was adopted in both bioassays. The LC50 of the oils varied from 7.50 to 60.84% (v/v). Copaifera sp. oil had the highest toxicity and was 6.84-fold more toxic than O. phalerata oil and 8.11-fold more toxic than Carapa guianensis oil. In general, oils from Copaifera sp., O. phalerata, and Carapa guianensis were effective in controlling S. frugiperda caterpillars under laboratory conditions, and are good candidates for use in integrated management programs of corn pests.

摘要 本研究探究了亚马逊西南部植物精油对草地贪夜蛾（Spodoptera frugiperda (J. E. Smith, 1797)，鳞翅目（Lepidoptera）：夜蛾科（Noctuidae））的潜在杀虫活性。本研究首先针对11种植物的未稀释精油开展初步生测，以其对草地贪夜蛾卵及3龄幼虫的防治效果作为评价指标。其中Copaifera属（Copaifera sp.，豆科（Leguminosae））、Orbignya phalerata（棕榈科（Arecaceae））以及圭亚那楝（Carapa guianensis，楝科（Meliaceae））的精油对幼虫展现出较高的杀虫活性，因此后续采用预实验确定的浓度梯度开展浓度-反应生测。本研究计算得到了各精油的最高非致死浓度与最低致死浓度，两类生测均采用完全随机设计方案。三种精油的半致死浓度（LC50）范围为7.50%~60.84%（体积比，v/v），其中Copaifera属精油的杀虫毒性最强，其毒性是O. phalerata精油的6.84倍，是圭亚那楝精油的8.11倍。总体而言，亚马逊西南部的该三种植物精油在实验室条件下可有效防治草地贪夜蛾幼虫，具备应用于玉米害虫综合治理项目的良好潜力。