Data from: A pragmatic approach to the analysis of diets of generalist predators: the use of next-generation sequencing with no blocking probes

Predicting whether a predator is capable of affecting the dynamics of a prey species in the field implies the analysis of the complete diet of the predator, not simply rates of predation on a target taxon. Here, we employed the Ion Torrent next-generation sequencing technology to investigate the diet of a generalist arthropod predator. A complete dietary analysis requires the use of general primers, but these will also amplify the predator unless suppressed using a blocking probe. However, blocking probes can potentially block other species, particularly if they are phylogenetically close. Here, we aimed to demonstrate that enough prey sequence could be obtained without blocking probes. In communities with many predators, this approach obviates the need to design and test numerous blocking primers, thus making analysis of complex community food webs a viable proposition. We applied this approach to the analysis of predation by the linyphiid spider Oedothorax fuscus in an arable field. We obtained over two million raw reads. After discarding the low-quality and predator reads, the libraries still contained over 61 000 prey reads (3% of the raw reads; 6% of reads passing quality control). The libraries were rich in Collembola, Lepidoptera, Diptera and Nematoda. They also contained sequences derived from several spider species and from horticultural pests (aphids). Oedothorax fuscus is common in UK cereal fields, and the results showed that it is exploiting a wide range of prey. Next-generation sequencing using general primers but without blocking probes provided ample sequences for analysis of the prey range of this spider and proved to be a simple and inexpensive approach.要预测捕食者在野外能否影响猎物种群动态，需对捕食者的完整食谱开展全面分析，而非仅关注其对单一目标类群的捕食率。本研究采用Ion Torrent 下一代测序技术（next-generation sequencing），对一种广食性节肢动物捕食者的食谱进行探究。完整的食谱分析需使用通用引物，但通用引物会同时扩增捕食者自身的序列，除非借助封闭探针（blocking probe）对其进行抑制。然而，封闭探针可能会同时抑制其他物种的序列扩增，尤其当物种间系统发育关系较近时。本研究旨在证明，无需使用封闭探针即可获取足够的猎物序列数据。在捕食者类群丰富的群落中，该方法无需设计并测试大量封闭引物，从而使复杂群落食物网的分析成为可行方案。我们将该方法应用于农田中皿蛛科（Linyphiidae）蜘蛛暗色微蛛（Oedothorax fuscus）的捕食行为分析。本次实验共获取超过200万条原始读段（raw reads）。剔除低质量读段及捕食者自身序列读段后，测序文库仍保留超过61000条猎物序列读段（占原始读段的3%；占通过质量质控的读段的6%）。测序文库中富集了弹尾纲（Collembola）、鳞翅目（Lepidoptera）、双翅目（Diptera）及线虫动物门（Nematoda）的序列。此外，文库中还包含多种蜘蛛及园艺害虫蚜虫（aphids）的序列。暗色微蛛（Oedothorax fuscus）在英国谷类作物田广泛分布，本研究结果表明其可捕食多种猎物。采用通用引物但无需封闭探针的下一代测序技术，可为该蜘蛛的猎物范围分析提供充足的序列数据，且该方法简便易行、成本低廉。