Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/8/2025
Publication Date: 4/23/2025
Citation: Pekarcik, A.J., Taylor, C.G., Raudenbush, A.L., Tilmon, K.J. 2025. Biocontrol potential of naturally occurring entomopathogens against Maladera formosae in corn-soybean rotated systems. Pest Management Science. https://doi.org/10.1002/ps.8851.
DOI: https://doi.org/10.1002/ps.8851

Interpretive Summary: BACKGROUND: The Asiatic garden beetle (Maladera formosae) emerged as a significant early season pest of field corn in the Great Lakes region beginning in the mid-2000s. The grubs feed on roots of corn seedling in springtime, causing plants to stunt, wilt, discolor, and die. Management tools used broadly to control annual white grub species, like insecticides, are ineffective against or have not been evaluated specifically for use against this species. Biological control, including insect-killing nematodes, is successful against Asiatic garden beetle in turf systems. The goals of this study were to 1) isolate and identify insect-killing nematode species from agricultural fields in northern Ohio infested with Asiatic garden beetle, and 2) evaluate their ability to infect Asiatic garden beetle grubs in greenhouse and field trials. RESULTS: We isolated two species of insect-killing nematodes fom six field sites including Heterorhabditis bacteriophora and Steinernema carpocapsae, in addition to a free-living nematode, Pristionchus sp. The presence of nematodes in the field was not correlated with soil physical properties like percent sand, silt, or clay. Additionally, the nematodes isolated varied among field sites. We confirmed that all three nematodes can infect and kill Asiatic garden beetle grubs. In a greenhouse study, treatments of the nematodes H. bacteriophora, and H. bacteriophora + Pristionchus sp. in combination killed significantly more grubs than having no nematodes. In an outdoor microcosm study, nematodes successfully survived winter and killed Asiatic garden beetle grubs at similar rates in late Spring, regardless of nematode treatment or inoculation rate. CONCLUSION: These findings indicate that insect-killing nematodes are prevalent in corn-soybean systems with Asiatic garden beetle and have the potential to be an effective tool for the management of this pest in field cropping systems in the Great Lakes region.

Technical Abstract: BACKGROUND: The Asiatic garden beetle, Maladera formosae, emerged as a significant early season pest of field corn in the Great Lakes region beginning in the mid-2000s. Management tools used broadly for annual white grub species, like seed- and soil-applied insecticides, are ineffective against or have not been evaluated specifically for M. formosae. Biological control, including entomopathogenic nematodes, is successful against M. formosae in turf systems. The goals of this study were to 1) isolate and identify nematode species from agricultural fields in northern Ohio with field histories of M. formosae, and 2) evaluate their ability to infect M. formosae grubs in greenhouse and field trials. RESULTS: We isolated two naturally occurring entomopathogenic nematode species from the field including Heterorhabditis bacteriophora and Steinernema carpocapsae, in addition to a free-living Pristionchus sp. nematode. The entomopathogen communities sampled varied among field sites and were not correlated with soil physical properties or M. formosae. We confirmed that all three nematodes can infect and kill M. formosae grubs. In a greenhouse study, H. bacteriophora and H. bacteriophora + Pristionchus sp. killed significantly more grubs than the water control. In an outdoor microcosm study, nematodes successfully overwintered and subsequently killed M. formosae grubs at similar rates, regardless of treatment or inoculation rate. CONCLUSION: These findings indicate that insect-killing nematodes are prevalent in corn-soybean systems with M. formosae and have the potential to be an effective tool for the management of M. formosae in field cropping systems in the Great Lakes region.