Effects of plant community composition on epigeal arthropods

Epigeal arthropods form the backbone of ecosystem services in many agricultural and natural settings, with carabid beetles and spiders playing a major role as generalist predators and weed biocontrol agents. Non-crop habitat can affect epigeal arthropods in multiple ways, such as providing refuge for both prey items and predators, and serving as an alternative food source, the effects of which can vary with plant community composition. To test these changes in composition, we examined how epigeal arthropod identity and activity-density varied across six different pollinator plantings within an agricultural setting in North Dakota established in 2024 : 1) alfalfa, 2) commercially available pollinator mix, 3) treatment 2 plus alfalfa, 4) cover crop mix, 5) native U.S. plants, and 6) native North Dakota plants. Epigeal arthropods were sampled for 1 week each month using pitfall traps, with one trap in the center of each plot with 25 cm long plastic guide walls extending from each trap in an X pattern. Carabid beetle populations were significantly higher in the native U.S. and North Dakota treatments due to the greater diversity of food items available and the adaptations of native species to prefer each other. Our findings provide insight into how plant diversification can affect epigeal arthropods.