Ivermectin is a powerful antiparasitic drug commonly used in cattle. Ivermectin residues are excreted in dung, threatening non-target coprophagous fauna such as dung beetles. This can have severe ecological and economic consequences for dung degradation and soil fertility. Even though the negative effects of direct ivermectin exposure on dung-degrading organisms are well known, effects could extend across generations. Here, we tested the effects of paternal or maternal exposure to ivermectin on offspring in the dung beetle Euoniticellus intermedius. This species is a classic study subject in ecotoxicology and sexual selection because males have a cephalic horn that is under intense selection via male-male competition. After confirming a negative effect of ivermectin on the number of emerged beetles, we found trans-generational effects of ivermectin exposure on the horn size of male offspring. Surprisingly however, this trans-generational effect only occurred when only the father was exposed. We detected no trans-generational effects of ivermectin exposure on offspring number, sex ratio or body size. Our results confirm that ivermectin not only has a strong effect on exposed individuals but also in their progeny. Our study opens new questions about the mechanisms responsible for parental effects and their long-term fitness consequences in contaminated habitats.

伊维菌素是牛中常用的强大抗寄生虫药。伊维菌素残留物在粪便中排出，威胁到非目标的共食性动物，例如粪便甲虫。这可能对粪便的降解和土壤肥力产生严重的生态和经济影响。尽管直接暴露伊维菌素对降解粪便的生物的负面影响是众所周知的，但这种影响可能会延续到几代人。在这里，我们测试了父本或母本接触伊维菌素对粪甲虫Euoniticellus intermedius的后代的影响。该物种是生态毒理学和性选择的经典研究对象，因为雄性的头角在通过雄性-雄性竞争而受到强烈选择时。在确认伊维菌素对出现的甲虫数量有负面影响后，我们发现了伊维菌素暴露对雄性后代角大小的跨代影响。然而，令人惊讶的是，这种跨代效应只有在只有父亲被暴露时才发生。我们没有发现伊维菌素暴露对后代数量，性别比或体型没有影响。我们的结果证实，伊维菌素不仅对暴露的个体有强烈的作用，而且对他们的后代也有很强的作用。我们的研究提出了新的问题，即造成父母影响的机制及其在受污染的生境中的长期适应后果的新问题。