To understand and improve the stability of the insecticidal activity of tobacco extract, the 3rd instar larvae of Malacosoma neustria testacea was determined by the leaf film method. Spectrophotometry identified extract effects on activities of several enzymes. In addition, to improve the stability of the extract, microcapsules were prepared by complex coacervation and phase separation with the extract as core material, and gelatin and gum arabic as wall material. With the embedding rate as the evaluation index, the response surface method was used to optimize the preparation process of the microcapsules. The results show that the extract had a strong insecticidal activity on the larvae, with inhibitory effects on several enzymes examined of carboxylesterase, acetylcholinesterase, glutathione-S transferase, catalase, and superoxide dismutase. The inhibition rate increased with time. The best preparation process of tobacco extract microcapsules was 25% mass fraction of emulsifier, 2.05% mass fraction of gelatin, 3% mass fraction of gum arabic, 1.34 wall core ratio, 36 min of complex coacervation time. The embedding rate was 58.4% which is approximately the theoretical embedding rate (58.9%). The microcapsules prepared by this method have a smooth surface, good combining form and particle size distribution, and a median diameter of 8.6 μm. Infrared characteristic peaks of the extracts were preserved at 877.55 cm^‒1 and 2922.13 cm^‒1. Microencapsulation can improve the thermal stability of the tobacco extract. Indoor toxicity tests showed that LC₅₀ of extract microcapsules was 20.2 mg·mL^‒1, equivalent to the toxicity level of the tobacco extract itself, indicating that microencapsulation did not reduce extract insecticidal effects. This research may provide a reference for the optimization of the tobacco extract microcapsule preparation process.

为了了解和提高烟草提取物的杀虫活性的稳定性，这是一种新的疟原虫的第三龄幼虫用叶膜法测定。分光光度法鉴定了提取物对几种酶活性的影响。另外，为了提高提取物的稳定性，以提取物为核心材料，以明胶和阿拉伯胶为壁材料，通过复合凝聚和相分离制备微胶囊。以包埋率作为评价指标，采用响应面法优化了微胶囊的制备工艺。结果表明，该提取物对幼虫具有很强的杀虫活性，对所检测的几种酶具有抑制作用，这些酶包括羧酸酯酶，乙酰胆碱酯酶，谷胱甘肽-S转移酶，过氧化氢酶和超氧化物歧化酶。抑制率随时间增加。烟草提取物微胶囊的最佳制备工艺是乳化剂的质量分数为25％2。明胶质量分数为05％，阿拉伯胶质量分数为3％，壁核比为1.34，复杂凝聚时间为36分钟。嵌入率是58.4％，大约是理论嵌入率（58.9％）。通过这种方法制备的微胶囊具有光滑的表面，良好的结合形式和粒度分布，并且中值直径为8.6μm。提取物的红外特征峰保留在877.55 cm^-1和2922.13厘米^-1。微囊化可以改善烟草提取物的热稳定性。室内毒性试验表明，提取物微胶囊的LC ₅₀为20.2 mg·mL ^‒1，与烟草提取物本身的毒性水平相当，表明微囊化并未降低提取物的杀虫作用。该研究可为优化烟草提取物微胶囊制备工艺提供参考。