Distributional patterns of fall armyworm parasitoids in a corn field and pasture field in Florida

Authors: HAY-ROE, MIRIAN - University Of Florida; Meagher, Robert - Rob; Nagoshi, Rodney; NEWMAN, YOANA - University Of Florida

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/2016
Publication Date: 5/1/2016
Citation: Hay-Roe, M.M., Meagher Jr, R.L., Nagoshi, R.N., Newman, Y. 2016. Distributional patterns of fall armyworm parasitoids in a corn field and pasture field in Florida. Biological Control. 96:48-56.
DOI: https://doi.org/10.1016/j.biocontrol.2016.02.003

Interpretive Summary: The fall armyworm moth is a serious pest of row and vegetable crops in the U.S. This pest insect has two major feeding strains, the corn strain that prefers eating on corn and sorghum and the rice strain that prefers pasture and turf grasses. Caterpillars of both strains are attacked by a wide variety of parasites that can be used as biocontrol agents. However, little is known about the identity and biology of most of these parasites. Researchers at USDA, Agricultural Research Service, Center for Medical, Agricultural and Veterinary Entomology in Gainesville, Florida, in collaboration with colleagues from University of Florida, conducted field experiments in corn fields and grass pastures in northern Florida to determine the natural parasites present, to assess whether parasites attack both strains at the same rate and whether the different parasites are located in the same areas of the fields. The results showed that in corn fields parasitoid wasps were the most abundant parasites while in pastures flies constituted the most abundant parasites and that they all parasitized both fall armyworm strains. Within the fields, some species were more common at the edge while others were more common towards the middle. These results will assist in developing strategies for enhanced biocontrol of the fall armyworm through placement of attractive flowering plants to modify parasite localization within a field.

Technical Abstract: An assessment of parasitoids and their selective patterns among Spodoptera frugiperda corn and rice host strains was performed from August 2008-August 2010 in a corn crop and a grass pasture in northern Florida under different seasonal conditions (spring and fall). Sentinel larvae from our laboratory were placed in both habitats. Results obtained in the corn crop differed from those in the pasture due to poor recovery rate of larvae in the pasture habitat. In corn fields, we found that the parasitoid community was composed of eight species of Hymenoptera and one Diptera species, which represented four families and two guilds. The more abundant parasitoid species in the corn field included Aleiodes laphygmae, Meteorus autographae, Cotesia sp., Euplectrus platyhypenae and Ophion flavidus while the Diptera species constituted the most abundant parasitoid in pastures. Among the parasitoid species collected in pastures were three Diptera species and four hymenoptera species. Parasitoid species did not discriminate among fall armyworm host strains, however they varied among the different habitats in the corn field. The ectoparasitoid Euplectrus platyhypenae and an unknown ichneumonid species were found primarily at the edges of the crop (in areas adjacent to the woods); while the endoparasitoids Cotesia sp. and Meteorus sp. were recovered more often in the main corn crop. Meteorus and Ophion were more abundant in the spring while the unknown ichneumonid was more abundant in the fall. Predator species differ among corn and pasture, which might contribute to the dynamics of parasitoid species in these fields.