The insect immune system includes several mechanisms responsible for defending against pathogens, parasites, and parasitoids. Some botanical insecticides, such as Azadirachta indica oil, cause changes in the immune system of various insect species. Spodoptera frugiperda is an important agricultural pest; thus, knowledge about the effect of neem oil on the immune system of this species can assist in its management. This study aimed to evaluate the effect of A. indica oil on the immune system of S. frugiperda. Caterpillars (2–3 mg) were placed individually in containers (50 ml) with approximately 10 g of diet, containing 125, 250, and 500 ppm of neem oil with propanone; the control group received only the propanone diet. In four experiments, the total number of hemocytes, the phagocytic activity, the activity of lysozyme-like enzymes, and phenoloxidase activity were measured in caterpillars at the end of the sixth instar. The total number of hemocytes in insects exposed to neem oil was 21% lower than in the control group. The percentage of cells that phagocyted the latex beads was similar among the caterpillars that ingested the different concentrations. The mean diameter of cell lysis halos was reduced only at concentrations of 125 and 250 ppm. Absorbance did not differ between treatments. Knowing that this oil reduces the number of circulation cells and the activity of lysozyme-like enzymes is of great importance to design control strategies, once the neem oil could be added to other biological agents for mortality reducing the chances of this insect surviving in the environment.

中文翻译：

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印楝（无患子目：楝科）油对草地贪夜蛾（鳞翅目：夜蛾科）幼虫免疫系统的影响。


昆虫免疫系统包括多种负责防御病原体、寄生虫和拟寄生物的机制。一些植物杀虫剂，例如印楝油，会导致各种昆虫的免疫系统发生变化。草地贪夜蛾(Spodoptera frugiperda)是一种重要的农业害虫；因此，了解印楝油对该物种免疫系统的影响有助于对其进行管理。本研究旨在评价印度草油对草地贪夜蛾免疫系统的影响。将毛毛虫（2-3 毫克）单独放入装有约 10 克饲料的容器（50 毫升）中，其中含有 125、250 和 500 ppm 的印楝油和丙酮；对照组仅接受丙酮饮食。在四个实验中，测量了第六龄末毛毛虫的血细胞总数、吞噬活性、类溶菌酶活性和酚氧化酶活性。接触印楝油的昆虫的血细胞总数比对照组低 21%。在摄入不同浓度的毛毛虫中，吞噬乳胶珠的细胞百分比相似。仅当浓度为 125 和 250 ppm 时，细胞裂解晕的平均直径才会减小。处理之间的吸光度没有差异。了解这种油会减少循环细胞的数量和类溶菌酶的活性，对于设计控制策略非常重要，一旦印楝油可以添加到其他生物制剂中以降低这种昆虫在环境中生存的机会，以降低死亡率。