Data from: Diet shifts by adult flightless dung beetles Circellium bacchus, revealed using DNA metabarcoding, reflect complex life histories

Life history changes may change resource use. Such shifts are not well understood in the dung beetles, despite recognized differences in larval and adult feeding ability. We use the flightless dung beetle Circellium bacchus to explore such shifts, identifying dung sources of adults using DNA metabarcoding, and comparing these with published accounts of larval dung sources. C. bacchus is traditionally considered to specialise on the dung of large herbivores for both larval and adult feeding. We successfully extracted mammal DNA from 151 adult C. bacchus fecal samples, representing 16 mammal species (ranging from elephants to small rodents), many of which are hitherto undescribed in the diet. Adult C. bacchus showed clear dung source preferences, especially for large herbivores inhabiting dense-cover vegetation. Our approach also confirmed the presence of cryptic taxa in the study area, and we propose this may be used for biodiversity survey and monitoring purposes. Murid rodent feces were the most commonly fed-upon dung source (77.5%) for adult C. bacchus, differing markedly from the large and megaherbivore dung sources used for larval rearing. These findings support the hypothesis of life history-specific shifts in resource use in dung beetles, and reveal a hitherto unsuspected, but ecologically important, role of these dung beetles in consuming rodent feces. The differences in feeding abilities of the larval and adult life history stages have profound consequences for their resource use and foraging strategies, and hence the ecological role of dung beetles. This principle and its ecological consequences should be explored in other scarabaeids.

生活史变化可能会改变资源利用模式。尽管蜣螂的幼虫与成虫取食能力存在公认差异，但学界对这类资源利用转变的认知仍较为匮乏。本研究以无飞行能力的蜣螂Circellium bacchus为研究对象，探究此类资源利用转变：通过DNA宏条形码（DNA metabarcoding）技术鉴定成虫的粪便食源，并将其与已发表的幼虫粪便食源记录进行对比。传统上认为，C. bacchus的幼虫和成虫均以大型草食动物的粪便为专一食源。本研究成功从151份成虫C. bacchus的粪便样本中提取到哺乳动物DNA，涵盖16种哺乳动物（从大象到小型啮齿动物），其中多数类群在其此前的食性记录中未被提及。成虫C. bacchus表现出明确的粪便源偏好，尤其偏好栖息于密被植被生境的大型草食动物粪便。本研究方法还证实了研究区域内存在隐存分类单元，我们认为该方法可用于生物多样性调查与监测工作。成虫C. bacchus最常取食的粪便源为鼠科啮齿动物粪便（占比77.5%），这与幼虫饲养阶段所使用的大型及巨型草食动物粪便来源存在显著差异。本研究结果支持蜣螂资源利用存在生活史特异性转变的假说，并揭示了这类蜣螂取食啮齿动物粪便的、此前未被认知但具有重要生态学意义的生态功能。幼虫与成虫生活史阶段取食能力的差异，对其资源利用与觅食策略乃至蜣螂的生态功能均具有深远影响。该原理及其生态学效应应在其他金龟子科（Scarabaeidae）类群中开展进一步研究。