“Slugs? In my guts?” Slug predators revealed from gut analysis of ground beetles

• Trinity Antoszewski, Insect Ecology and Conservation, University of Delaware

• Michael Crossley, Entomology and Wildlife Ecology, University of Delaware

Slugs are a key pest of no-till corn and soybean in the US Mid-Atlantic, causing millions of dollars of damages and pesticide expenditures. Biocontrol, which is the use of natural enemies to manage pest species, could be a promising alternative to pesticide applications to control slugs. One group of insects in particular, ground beetles (Coleoptera: Carabidae), is known to include slug predators, but the extent to which the ground beetle species present in the US Mid-Atlantic are preying on slugs is unknown. Here, we used molecular gut content analysis to assess the extent of slug-feeding in five ground beetle species found in Delaware and Maryland: Agonum octopunctatum, Amphasia serica, Chlaenius tricolor, Poecilus lucublandus, and Scarites quadriceps. Curiously, the carnivorous species tested (C. tricolor and S. quadriceps) fed on slugs less frequently than the omnivorous species (i.e., their diets are known to also include seeds): out of the omnivorous species, 71% of the samples tested had slug DNA in them, while only 29% of the carnivorous species tested had slug DNA. Examination of more carnivorous and omnivorous species could reveal if this is a general trend. More broadly, our results suggest that efforts to promote ground beetles in the landscape could facilitate natural suppression of slugs.