DNA metabarcoding of gut contents reveals key habitat and seasonal drivers of trophic networks involving generalist predators in agricultural landscapes

BACKGROUND Understanding the networks of trophic interactions into which generalist predators are embedded is key to assessing their ecological role of in trophic networks and the biological control services they provide. The advent of affordable DNA metabarcoding approaches greatly facilitates quantitative understanding of trophic networks and their response to environmental drivers. Here, we examine how key environmental gradients interact to shape predation by Lycosidae in highly dynamic vegetable growing systems in China. RESULTS For the sampled Lycosidae, crop identity, pesticide use and seasons shape the abundance of prey detected in spider guts. For the taxonomic richness of prey, local- and landscape-scale factors gradients were more influential. Multivariate ordinations confirm that these crop-abundant spiders dynamically adjust their diet to reflect environmental constraints and seasonal availability to prey. CONCLUSION Plasticity in diet composition is likely to account for the persistence of spiders in relatively ephemeral brassica crops. Our findings provide further insights into the optimization of habitat management for predator-based biological control practices. (c) 2022 Society of Chemical Industry.

Automated summary

This study highlights how environmental gradients interact to shape predation by Lycosidae in vegetable growing systems, with factors such as crop identity, pesticide use, and seasons influencing prey abundance in spider guts. It also shows that the taxonomic richness of prey is influenced by local- and landscape-scale factors, and that crop-abundant spiders adjust their diet to reflect environmental constraints and seasonal prey availability. Plasticity in diet composition is suggested to contribute to the persistence of spiders in ephemeral brassica crops, providing insights for habitat management in predator-based biological control practices.