The fall armyworm (FAW), Spodoptera frugiperda, is an invasive and destructive pest to certain strategic crops, especially maize in Egypt. This research was conducted mainly to obtain secondary metabolites from some wild plants and fungal strains, use them in controlling FAW, and investigate their mode of action. The ethyl acetate extracts of Cladosporium cladosporioides and Verticillium lecanii, as well as the alkaloid extracts of Ricinus communis and Nicotiana glauca, were extracted to obtain their secondary metabolites. The secondary metabolite contents were identified by gas chromatography mass spectrometry and NMR. The toxicity of all extracts against the 3rd-instar larvae of FAW was evaluated. The possible mode of action of the extracts was studied via their effects on larval enzyme activities and larval tissue. The toxicity results illustrated that, the extract of C. cladosporioides was more effective with LC50 229 ppm, followed by the extract of V. lecanii with LC50 341 ppm and N. glauca with LC50 404 ppm, while the least effective extract was R. communis with LC50 1110 ppm after 72 h of treatment. While, the results of larval enzyme activities showed that C. cladosporioides, V. lecanii, and R. communis extracts led to significant activity of AST, ALT, ACP, and ALP enzymes, but GST and AchE were inhibited in treated larvae compared with control. While N. glauca alkaloid extract caused significant inhibition of AST, ALT, ACP, AchE, and GST enzymes, ALP was activated in the treated larvae compared with control. The results of larval tissue slides indicated that the most affected tissues were the cuticle layer and the membrane lining of the midgut, in addition to the fatty bodies. Thus, natural pesticides would have a promising role in terms of controlling the FAW and according to this study, it was recommended that, alkaloid extracts of tested wild plants and ethyl acetate extracts of fungal strains be used as natural pesticides to control the fall armyworm, S. frugiperda.

中文翻译：

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一些真菌菌株和野生植物的次生代谢产物作为天然杀虫剂对抗草地贪夜蛾的杀虫活性和可能的​​作用方式

秋粘虫 (FAW) 草地贪夜蛾 (Spodoptera frugiperda) 是一种对某些战略作物（尤其是埃及的玉米）具有入侵性和破坏性的害虫。本研究主要是从一些野生植物和真菌菌株中获取次生代谢产物，用于防治秋粘虫，并探讨其作用方式。提取枝孢枝孢和黄萎病菌的乙酸乙酯提取物，以及蓖麻和青烟草的生物碱提取物，获得其次生代谢产物。通过气相色谱质谱和核磁共振鉴定次级代谢产物含量。评估了所有提取物对秋粘虫三龄幼虫的毒性。通过提取物对幼虫酶活性和幼虫组织的影响，研究了提取物可能的作用方式。毒性结果表明，C. cladosporioides 提取物的 LC50 为 229 ppm，效果较好，其次是 V. lecanii 提取物，LC50 341 ppm，N. glauca 的 LC50 404 ppm，而效果最差的是 R. communis 提取物。处理 72 小时后，LC50 为 1110 ppm。同时，幼虫酶活性结果表明，与对照相比，C. cladosporioides、V. lecanii 和 R. communis 提取物导致 AST、ALT、ACP 和 ALP 酶显着活性，但 GST 和 AchE 受到抑制。 。虽然 N. glauca 生物碱提取物对 AST、ALT、ACP、AchE 和 GST 酶产生显着抑制，但与对照相比，处理过的幼虫中 ALP 被激活。幼虫组织切片的结果表明，除了脂肪体之外，受影响最严重的组织是角质层和中肠的膜层。因此，天然农药在控制草地贪夜蛾方面具有广阔的前景，根据本研究，建议使用受试野生植物的生物碱提取物和真菌菌株的乙酸乙酯提取物作为天然农药来控制草地贪夜蛾，果蝇。