Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/9/2007
Publication Date: 6/1/2007
Citation: Meagher Jr, R.L., Mislevy, P., Nagoshi, R.N. 2007. Caterpillar (Lepidoptera: Noctuidae) feeding on pasture grasses in central florida. Florida Entomologist. 90:295-303. Interpretive Summary: Fall armyworm and striped grass loopers infest forage grass, turf grass, corn, and sorghum plantings in the southeastern United States. In Florida, both species can be serious pests of subtropical bermudagrasses, stargrasses, and corn. Two entomologists at the Center for Medical, Agricultural and Veterinary Entomology (CMAVE), Gainesville, Florida, and an agronomist at the University of Florida, conducted field experiments in south-central Florida to document populations levels on a seasonal basis and to determine if some grass varieties sustained more damage than others. Laboratory experiments conducted at CMAVE showed that both fall armyworm and looper larvae developed faster and were heavier when fed stargrass varieties than varieties of bermudagrass. These results will help beef cattle growers who use forage grasses for pasture and hay production select varieties that may offer lower population levels of these pests.
Technical Abstract: Stargrasses (Cynodon nlemfuensis Vanderyst var. nlemfuensis) and bermudagrasses [C. dactylon (L.) Persoon] are important warm weather forage grasses, with several varieties developed and optimized for conditions found in central and southern Florida. Major insect pests of these grasses include grass loopers (Mocis spp.) and fall armyworm [Spodoptera frugiperda (J. E. Smith)], which annually impose substantial economic effect on pasture lands. Population studies conducted during a three-year period showed that both species had similar profiles with respect to larval population seasonality but not abundance. Plot studies with four stargrass and four bermudagrass lines showed that higher grass looper populations were found in stargrasses than bermudagrasses. These results correlated with laboratory studies that found grass loopers and fall armyworm larvae generally developed faster with larger weights on lines of stargrass than lines of bermudagrass. It was also found that the two fall armyworm host strains can differ substantially in their larval weight, developmental time, and survivability when grown on different lines of grasses. These results indicate that the selection of pasture grasses made by growers can significantly and differentially affect the population densities of these grass defoliators.