Spider (Araneae) abundance and species richness comparison between native wildflower plantings and fallow controls in intensively managed agricultural areas

Abstract

Large-scale agriculture has led to a loss of overall biodiversity and ecosystem services (e.g., biological control) within farmland. Native wildflower plantings have been used to restore ecosystem services and increase conservation measures within agricultural areas. In this study, we examined spider (Araneae) communities within small wildflower plots and fallow control plots that were primarily composed of grasses. Utilizing multiple trapping schemes (pitfalls, sweep netting, and pan trapping), spiders were found to be more abundant within the wildflower plots compared to fallow controls but species richness or Shannon–Wiener diversity indices were not different between the two habitats. The sheet web-weaving spider, Ceraticelus tibialis, (Araneae: Linyphiidae) was more abundant within the fallow controls, whereas, some spider families (Lycosidae, and Oxyopidae) were significantly more abundant in the wildflower plots. Categorizing spiders into hunting/web-building guilds showed that ambushers, space, and stalkers were significantly more abundant in the wildflower plots but low-sheet/tangle weavers were significantly more abundant in the fallow controls. Our results suggest that wildflower plantings can be a successful way to increase overall spider abundance within intensive agricultural areas and, thus, may help contribute to biological control of pest insects. However, our results also suggest wildflower plantings may not be a useful conservation tool that increases spider biodiversity within agricultural areas.