We used high-throughput sequencing molecular gut content analysis (HTS-MGCA) to examine diets of the red imported fire ant (Solenopsis invicta; hereafter fire ant). Because adult fire ant workers rely on their larvae (brood) to digest prey and share it via trophallaxis with the rest of the colony, we conducted a study to determine if we could sequence the gut contents of final instar ant brood instead of adult workers to better capture colony diet. We sequenced all samples on the Illumina HiSeq 2500 using general primers to amplify and identify arthropod DNA within larval guts. We first verified our methods in a controlled-feeding experiment in the laboratory using crickets (Gryllodes sigillatus), beet armyworm (Spodoptera exigua), or a mixture of both species, and then we analyzed the diets of field-collected fire ants. The sequences from our controlled-feeding lab samples were very accurate, validating our analysis pipeline. We identified a total of 45 diet events from six field-collected fire ant samples. All fire ant field samples contained sequences from both detritus-based food webs (arthropods that consume decaying material) and plant-based food webs (arthropods that consume living plant material). HTS-MGCA of fire ant larvae was highly successful and provided novel insights into the community-level impacts of ant foraging. Our approach should be widely applicable to the study of resource use and trophic interactions in other eusocial insects.

我们使用高通量测序分子肠道含量分析 (HTS-MGCA) 来检查红色进口火蚁（Solenopsis invicta；以下简称火蚁）的饮食。因为成年火蚁工蚁依靠它们的幼虫（幼虫）消化猎物并通过滋养体与其他蚁群共享它，所以我们进行了一项研究，以确定我们是否可以对最终龄蚁幼体而不是成年工蚁的肠道内容物进行测序，以更好地捕获菌落饮食。我们使用通用引物在 Illumina HiSeq 2500 上对所有样本进行测序，以扩增和鉴定幼虫肠道内的节肢动物 DNA。我们首先在实验室使用蟋蟀（Gryllodes sigillatus）、甜菜夜蛾（Spodoptera exigua)，或两种物种的混合物，然后我们分析了野外采集的火蚁的饮食。我们控制喂食实验室样本的序列非常准确，验证了我们的分析流程。我们从六个现场收集的火蚁样本中确定了总共 45 个饮食事件。所有火蚁野外样本都包含来自基于碎屑的食物网（消耗腐烂材料的节肢动物）和基于植物的食物网（消耗活植物材料的节肢动物）的序列。火蚁幼虫的 HTS-MGCA 非常成功，并为蚂蚁觅食的社区影响提供了新的见解。我们的方法应该广泛适用于研究其他真社会性昆虫的资源利用和营养相互作用。