Molecular gut content analysis indicates the inter- and intra-guild predation patterns of spiders in conventionally managed vegetable fields

Inter- and intra-guild interactions are important in the coexistence of predators and their prey, especially in highly disturbed vegetable cropping systems with sporadic food resources. Assessing the dietary range of a predator taxon characterized by diverse foraging behavior using conventional approaches, such as visual observation and conventional molecular approaches for prey detection, has serious logistical problems. In this study, we investigated the trophic interactions of a functionally diverge group of predators -spiders- to accomplish the ultimate goal that is the predation of spiders on major crop pests. We used high-throughput sequencing (HTS) and biotic interaction networks to precisely annotate the predation spectrum and highlight the predator–predator and predator-prey interactions in Brassica fields. The prey taxa in the gut of spiders were mainly enriched with insects (including dipterans, coleopterans, orthopterans, hemipterans and lepidopterans) and arachnids (such as Araneae) along with a wide range of other prey factions. Despite the generalist foraging behavior of spiders, the community structure analysis and interaction networks highlighted the overrepresentation of particular prey taxa in the gut of each spider family, as well as showed the intra-family predation between different spiders. Identifying the diverse trophic niche proportions underpins the importance of spiders as predators of pests in highly disturbed agroecosystems. More specifically, combining HTS with advanced ecological community analysis reveals the preferences and biological control potential of particular spider taxa, so provides a valuable evidence base for targeted conservation biological control efforts in complex trophic networks.DNA extracted from spiders for DNA metabarcoding; amplified using primer pairs mlCOlintF and HCO2198; sequenced using Illumina MiSeq