Itol A, an isoryanodane diterpene derived from Itoa orientalis Hemsl. (Flacourtiaceae), is a potential plant-based insecticide. However, the effect of itol A on the tobacco cutworm [Spodoptera litura (Fab.) (Lepidoptera: Noctuidae)], an important and widely distributed insect pest, remains unclear. In this study, the toxicity and inhibitory potency of itol A on S. litura were evaluated. The results indicated that itol A exhibited larvicidal activity against the third instar larvae in a concentration-dependent manner (LC50 875.48 mg/L at 96 h). Antifeedant activity also was observed, and the 24-h AFC50 values were 562.05 and 81.47 mg/L in the no-choice and choice experiments, respectively. The insect growth was inhibited after treatment of itol A, as reflected by long developmental periods, low-quality pupae, and various abnormalities. Itol A exerted ovicidal effect on S. litura, with an estimated LC50 of 759.30 mg/L. Itol A deterred oviposition in the choice experiment (ODI50 909.60 mg/L). Besides, the activities of α-amylase, general protease, superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) were inhibited after itol A treatment over time compared to controls, which may be a relevant mechanism underlying the toxicity of itol A toward S. litura. However, the activities of lipase, carboxylesterase (CarE), glutathione S-transferase (GST), and cytochrome P450 monooxygenase (P450) were increased. Taken together, these results suggest that itol A could be a good botanical pesticide to reduce the population of S. litura in integrated pest management programs.

中文翻译：

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植物源农药醇 A 对烟草地老虎、斜纹夜蛾 (Spodoptera litura (Fab.)) 的作用。


Itol A，一种源自 Itoa orientalis Hemsl 的异草烷二萜。 （Flacourtiaceae）是一种潜在的植物性杀虫剂。然而，醇A对烟草地老虎[Spodoptera litura (Fab.)（鳞翅目：Noctuidae）]这一重要且分布广泛的害虫的影响仍不清楚。本研究评估了醇A对斜纹夜蛾的毒性和抑制效力。结果表明，醇A对三龄幼虫具有浓度依赖性杀幼虫活性（96 h时LC50 875.48 mg/L）。还观察到拒食活性，在无选择和选择实验中，24小时AFC50值分别为562.05和81.47 mg/L。醇A处理后，昆虫生长受到抑制，表现为发育周期长、蛹质量低、出现各种异常现象。 Itol A 对斜纹夜蛾具有杀卵作用，估计 LC50 为 759.30 mg/L。 Itol A 在选择实验中阻止了产卵 (ODI50 909.60 mg/L)。此外，与对照组相比，经过一段时间的醇A处理后，α-淀粉酶、普通蛋白酶、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和过氧化物酶（POD）的活性均受到抑制，这可能是其毒性的相关机制。醇A针对斜纹夜蛾。然而，脂肪酶、羧酸酯酶（CarE）、谷胱甘肽S-转移酶（GST）和细胞色素P450单加氧酶（P450）的活性增加。总而言之，这些结果表明，醇 A 可能是一种良好的植物源农药，可在害虫综合防治计划中减少斜纹夜蛾的数量。