Seasonal incidence and laboratory rearing of selected chloropid flies occurring in tall fescue in Tennessee

A two-year study was undertaken to determine seasonal population densities and emergence of chloropid flies (Diptera: Chloropidae) in endophyte-infected (E+) and noninfected (E-) tall fescue in Robertson Co., TN., and aspects of the biology of Rhopalopterum carbonarium. a common chloropid, were investigated. A total of 22 chloropid species or variants were collected in sweep samples and/or emergence traps during 1991-1992. Rhopalopterum carbonarium (Loew) was the most abundant chloropid collected in both years. Population densities of this and ten other species, were significantly lower in E+ plots than E- plots on several sampling dates; however, on no sampling dates were significantly more specimens collected from E+ plots than E- plots. Fewer chloropids emerged from E+ plots than from E- plots. Three known pest species of chloropids were collected during this study. Two plant feeders, Oscinella frit (Loew), the frit fly, and Meromyza americana Fitch, the wheat stem maggot, were collected in significantly fewer numbers in sweep samples from E+ plots than from E- plots on at least one occasion. Significantly fewer Liohippelates pallipes (Loew), one of the "eye gnats," emerged from E+ fescue clippings than from E- clippings. A colony of R. carbonarium was maintained in a growth chamber in 1991. R. carbonarium developed from egg to adult on dead E+ and E- fescue tissues and crabgrass. These studies revealed that population densities of chloropid flies with different larval habits are negatively affected by the presence of Acremonium coenophialum. Additional studies are needed to determine the possible effects of planting E- pastures on the pest status of chloropids occurring in tall fescue.