Chemical pesticides are the main tool used to handle lepidopteran insects in agriculture. However, in addition to causing environmental problems, the insects have acquired resistance to these molecules. Thus, the development of environmentally friendly biopesticides with higher specificity, such as organic protease inhibitors, has been encouraged. This work evaluated the inhibitory effects of two tripeptides, Pep1 and Pep2, obtained by removing the cleavage site of tripeptidyl substrates for trypsin-like proteases. Anticarsia gemmatalis were used as biochemical model and the trypsin-like activity of larvae exposed to different dosages of the tripeptides and protease inhibitors merged in an artificial diet was evaluated. Further, we selected one dose of each tripeptide to set a biological assay, where the total-proteolytic, cysteine-proteases, chymotrypsin-like and trypsin-like activities were determined. The tripeptides shown to have potential to inhibit trypsin-like serine proteases of A. gemmatalis midgut, being the lowest activity detected at doses of 170.4 μM and 251.2 μM for Pep1 and Pep2, respectively. The survival curves obtained using Kaplan-Meier estimators indicated that Pep2 and Pep1 affected survival when comparing to the control group. However, the effect of Pep1 on survival was more pronounced indicating the lowest percent of survival at the end of the larval phase (20%). In addition, larvae exposed to Pep1 maintained normal total proteolytic activity at the expense of the activities of chymotrypsin-like and cysteine proteases. Collectively, our findings revealed that the tripeptides, especially Pep1, exhibit toxic effects on A. gemmatalis and should be tested against other lepidopteran insects.

中文翻译：

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三肽对Anticarsia gemmatalis酶活性和生命周期参数的抑制作用

化学农药是农业中用于处理鳞翅目昆虫的主要工具。然而，除了造成环境问题外，昆虫还对这些分子产生了抗药性。因此，鼓励开发具有更高特异性的环境友好型生物农药，例如有机蛋白酶抑制剂。这项工作评估了通过去除胰蛋白酶样蛋白酶的三肽基底物的裂解位点获得的两种三肽 Pep1 和 Pep2 的抑制作用。Anticarsia gemmatalis 被用作生化模型，并评估了幼虫暴露于不同剂量的三肽和人工饮食中合并的蛋白酶抑制剂的胰蛋白酶样活性。此外，我们选择了一种剂量的每种三肽来设置生物测定，其中总蛋白水解酶、半胱氨酸蛋白酶、测定了胰凝乳蛋白酶样和胰蛋白酶样活性。三肽显示具有抑制 A. gemmatalis 中肠胰蛋白酶样丝氨酸蛋白酶的潜力，在 Pep1 和 Pep2 的剂量分别为 170.4 μM 和 251.2 μM 时检测到的活性最低。使用 Kaplan-Meier 估计器获得的生存曲线表明，与对照组相比，Pep2 和 Pep1 影响生存。然而，Pep1 对存活率的影响更为明显，表明幼虫期末存活率最低 (20%)。此外，暴露于 Pep1 的幼虫以胰凝乳蛋白酶样和半胱氨酸蛋白酶的活性为代价保持正常的总蛋白水解活性。总的来说，我们的研究结果表明，三肽，尤其是 Pep1，对 A.