Comparison of carabid densities in different cover crop species in north Florida

Authors: Meagher, Robert - Rob; BROWN, JAMES - University Of Florida; Miller, Neil; FLEISHER, SHELBY - Retired Non ARS Employee; BOWERS, KRISTEN - University Of Florida; HIGHT, STEPHEN - Retired ARS Employee; Legaspi, Jesusa; BROWN, ROBERT - Animal And Plant Health Inspection Service (APHIS); Nagoshi, Rodney; WRIGHT, DAVID - University Of Florida

Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/22/2023
Publication Date: 12/7/2023
Citation: Meagher Jr, R.L., Brown, J.T., Miller, N.W., Fleisher, S.J., Bowers, K., Hight, S.D., Legaspi, J.C., Brown, R.C., Nagoshi, R.N., Wright, D.L. 2023. Comparison of carabid densities in different cover crop species in north Florida. Florida Entomologist. 106(4):220-229. https://doi.org/10.1653/024.106.0403.
DOI: https://doi.org/10.1653/024.106.0403

Interpretive Summary: Fall armyworm is a migratory moth pest of row, turf and vegetable crops. As it migrates during spring from southern Florida and southern Texas, it feeds and develops on cover crops such as field corn and sorghum-sudangrass. Natural enemies, including predatory beetles (carabids), can feed on and decrease populations. Scientists with the USDA-ARS, Center for Medical, Agricultural and Veterinary Entomology in Gainesville, Florida, in collaboration with scientists from the University of Florida, tested the impact of alternate cover crop plants on carabid populations in the field. Three cover crop species, sorghum-sudangrass, cowpeas and sunn hemp, were grown in three locations in Florida. Pitfall traps were used to compare numbers of carabid beetles caught in different cover crop treatments. While almost 2,000 predatory and omnivorous carabid beetles were collected, there were no differences in beetle numbers among cover crop plants. Three species present, Calosoma sayi, Tetracha carolina, and Cicindela punctulata, are known to readily feed on different stages of fall armyworm. The presence of these species associated with the cover crops is promising as a potential tool for management of fall armyworm immatures.

Technical Abstract: Many ground beetle species (Coleoptera: Carabidae) prey on noctuid larvae and pupae. Therefore, agricultural practices that maintain or even enhance carabid populations have the potential to reduce noctuid pest populations through predation. One such pest is the fall armyworm, Spodoptera frugiperda (J. E. Smith), a migratory noctuid pest of row, turf and vegetable crops. Before migrating in spring from southern Florida and southern Texas, it feeds and develops on cover crops such as field corn and sorghum-sudangrass and expands its populations. Here we tested the impact of cover crops with differing capacity to support fall armyworm development on carabid populations in the field. Three cover crop species, sorghum-sudangrass, cowpeas and sunn hemp, were previously studied for their effects on fall armyworm populations, with sunn hemp showing high incompatibility with fall armyworm development. The cover crops were grown in three locations in north and north-central Florida and pitfall traps were used to compare numbers of carabid beetles caught in different cover crop treatments. Almost 2,000 predatory and omnivorous carabid beetles were collected. Three species in particular, Calosoma sayi Dejean, Tetracha carolina (L.), and Cicindela punctulata Olivier, readily feed on different stages of S. frugiperda in the laboratory and may aid in the reduction of damaging populations in the field. There were no differences in beetle numbers among cover crop plants. In another trial, more beetles were collected in plots of a popular sunn hemp cultivar developed in the southeastern U.S., ‘AU Golden’, than in plots of another germplasm line, Tillage Sunn™. Further research should determine if the predatory species found in this study prey on S. frugiperda in the field and if this added mortality helps reduce damaging populations.