A shift towards sustainable management for Japanese beetle

Japanese beetle (Popillia japonica Newman) is an invasive insect that continues to spread throughout the Midwestern United States. Adult beetles feed on over 300 host plant species including wild shrubs, hardwoods, and agricultural commodities, often resulting in severe economic damage. To manage Japanese beetle, field crop growers spray up to four additional insecticide applications per season, which have non-target effects on pollinators and natural enemies. To mitigate these non-target effects, we evaluated an attract-and-kill strategy using insecticidal nets in soybean. Attract-and-kill treatments consisted of 76 m of insecticidal net placed along a single field border baited with pheromone lures. Attract-and-kill treatments were compared with grower standard treatments (insecticide sprays) and non-treated negative controls. We quantified defoliation, seed damage, Japanese beetle abundance, functional group abundance, and herbivore feeding guild abundance. To quantify insect movement towards insecticidal nets, we protein-marked soybean fields with milk solution and the surrounding natural habitat with egg solution. We collected insects from treatments and assessed presence of protein markers with enzyme-linked immunosorbent assays. We found that herbivore abundance, including Japanese beetle, and overall predator abundance were greater in attract-and-kill treatments compared with grower standard treatments; however, attract-and-kill provided economically equivalent protection against defoliation. Surprisingly, attract-and-kill treatments had higher seed quality, potentially resulting from increased predator abundance compared to grower standard treatments.