Red de Ecoetología, Instituto de Ecología A.C, Xalapa, Mexico.
Centro Tlaxcala de Biología de La Conducta, Universidad Autónoma de Tlaxcala, Tlaxcala, Mexico; Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, CDMX, Mexico.
Chemosphere. 2021 Apr;269:128707. doi: 10.1016/j.chemosphere.2020.128707. Epub 2020 Oct 23.
Ivermectin is the most common antiparasitic drug used in livestock in many regions of the world. Its residues are excreted in dung, threatening non-target fauna such as dung beetles, fundamental for cleaning dung in pastures. However, it is unclear which are the physiological mechanisms used by dung beetles to cope with ivermectin. Here we evaluated experimentally the physiological responses of the dung beetle Euoniticellus intermedius to ivermectin-induced stress. We measured metabolic rates, heat shock protein 70 (Hsp70) expression, antioxidant capacity, and oxidative damage in lipids in both males and females exposed to a sublethal dose. Compared to control beetles, ivermectin-treated males and females had increased metabolic rates. Moreover, ivermectin-treated females increased their expression of Hsp70 whereas males increased their antioxidant capacity. No changes in the levels of oxidative damage to lipids were detected for either sex, suggesting a process of hormesis, such that exposure to a moderate concentration of ivermectin could stimulate the action of a protective mechanism against oxidative stress, that differs between sexes. However, it does not exclude the possibility that damage to other biomolecules might have occurred. Sexual differences in physiological responses can be interpreted as the result of hormonal differences or life-history trade-offs that favor different mechanisms in females and males. Hsps and antioxidants are involved in the physiological response of beetles to ivermectin and may be key in providing resistance to this contaminant in target and non-target species, including dung beetles.
伊维菌素是世界许多地区畜牧业最常用的驱虫药。它的残留物会随粪便排出，威胁到蜣螂等非靶标动物，而蜣螂对牧场中的粪便清理至关重要。然而，目前尚不清楚蜣螂是如何利用生理机制来应对伊维菌素的。在这里，我们实验评估了粪金龟 Euoniticellus intermedius 对伊维菌素诱导的应激的生理反应。我们测量了暴露于亚致死剂量的雄性和雌性蜣螂的代谢率、热休克蛋白 70（Hsp70）表达、抗氧化能力和脂质的氧化损伤。与对照甲虫相比，伊维菌素处理的雄性和雌性甲虫的代谢率增加。此外，伊维菌素处理的雌性甲虫增加了 Hsp70 的表达，而雄性甲虫增加了其抗氧化能力。两性的脂质氧化损伤水平均未发生变化，表明存在一种激素刺激作用，即暴露于中等浓度的伊维菌素可以刺激一种针对氧化应激的保护机制的作用，这种作用在两性之间存在差异。然而，这并不排除其他生物分子可能受到损害的可能性。两性在生理反应上的差异可以解释为激素差异或生活史权衡的结果，这有利于雌性和雄性采用不同的机制。热休克蛋白和抗氧化剂参与了甲虫对伊维菌素的生理反应，可能是包括蜣螂在内的靶标和非靶标物种对这种污染物产生抗性的关键。
