Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/6/2011
Publication Date: 8/1/2011
Citation: Beuzelin, J.M., Meszaros, A., Reagan, T.E., Wilson, L.T., Way, M.O., Blouin, D.C., Showler, A.T. 2011. Seasonal infestations of two stem borers (Lepidoptera: Crambidae) in noncrop grasses of Gulf Coast rice agroecosystems. Environmental Entomology. 40(5):1036-1050. Interpretive Summary: Two main stem borers of sugarcane in the United States are the sugarcane borer and the Mexican rice borer. Transect sampling in rice growing areas of the Texas Gulf Coast revealed that grasses in non-cropped areas (field margins and further beyond cultivated fields) serve as hosts for the borers, particularly for the Mexican rice borer. Some weed species are more commonly encountered in the winter; hence they serve as host plants until preferable hosts are available during the spring and summer.
Technical Abstract: Infestations of two stem borers, the Mexican rice borer, Eoreuma loftini (Dyar) and the sugarcane borer, Diatraea saccharalis (F.) (Lepidoptera: Crambidae), were compared in non-crop grasses adjacent to rice, Oryza sativa L., fields. Three farms in the Texas Gulf Coast rice production area were surveyed every 6-8 wk between 2007 and 2009 using quadrat sampling along transects. While sugarcane borer densities were relatively low, average Mexican rice borer densities ranged from 0.3 to 5.7 immatures per square meter throughout the two-year period. Early annual grasses, including ryegrass, Lolium spp., and brome, Bromus spp., were infested during the spring whereas the perennial johnsongrass, Sorghum halepense (L.) Pers., and Vasey’s grass, Paspalum urvillei Steud., were infested throughout the year. Johnsongrass was the most prevalent host (41-78% relative abundance), but Vasey’s grass (13-40% relative abundance) harbored as much as 62% of the recovered Mexican rice borer immatures (during winter). Young rice in newly planted fields did not host stem borers prior to June; April sampling in fallow rice fields showed that any available green grass material, volunteer rice or weed, can serve as a host during the spring. Our study suggests that non-crop grasses are year-round sources of Mexican rice borers in Texas rice agroecosystems and may increase pest populations.