Parasitoids of the bean leaf beetle (Coleoptera : Chrysomelidae) found in Nebraska soybean fields

The bean leaf beetle, Cerotoma trifurcata (Forster) (Coleoptera: Chrysomeli dae), is the major insect pest of soybean in Nebraska and throughout much o f the midwestern United States. Natural enemies of the bean leaf beetle hav e been reported in other states, but none have been reported in Nebraska. I n this study, bean leaf beetle adults were obtained by aspirating those fou nd on soybean plants early in the season and by sweep net once plants were in the V4 stage (approximately 0.33 meter tall). Sampling was done in 1997 and 1998 in soybean fields at the University of Nebraska Agricultural Resea rch and Development Center in Saunders County in east-central Nebraska. Bee tles were taken to the laboratory and reared to monitor for parasitoid emer gence or preserved in ethyl alcohol for later examination for external para sitic mites. Nine tachinid parasitoids emerged from nine of the beetles tha t were collected in 1997 and identified as Celatoria sp. (species undescrib ed) (Diptera: Tachinidae). Percentage of beetles infested with the parasito id ranged from zero to 1.1. Ectoparasitic mites, identified as Trombidium h yperi Vercammen-Grandjean, Van Driesche, and Gyrisco (Acari: Trombidiidae), were found under the elytra on six of the preserved beetles from 1997 and 16 of the beetles from 1998. A total of 8 mites were found in 1997 and 55 w ere found in 1998. Percentage of beetles infested with the mites ranged fro m 0-4 in 1997 and from 0-40 in 1998. This is the first report of natural en emies of the bean leaf beetle from Nebraska. This information may be useful to those developing integrated pest management strategies for the bean lea f beetle in the future.