The Impact of Sewage Effluent on the Occurrence of Psychodidae (Diptera) in a Stream

Abstract

A total of twenty-two species of Psychodidae was collected from two streams in northwestern Pennsylvania from 1979-1981, using aquatic emergence traps. At Fourmile Creek, 644 specimens were collected from two sites, one upstream and one downstream from a discharge of sewage effluent, while at another control site (Sixmile Creek), 257 specimens were collected. At the sewage affected site in 1981, 13 species were collected with Psychoda parthenogenetica (Tonnoir) accounting for 65% and Tinearia alternata (Say) 19% of the collection while at the upstream site 16 species were collected. Telmatoscopus quadripunctatus (Banks) accounted for 19% in 1981 and Tinearia limicola (Vaillant) 33% in 1980 at this upstream site. At Sixmile Creek in 1981, 13 species were collected and Quateiella interdicta (Dylar) (43%) was most abundant while in 1979 Panimerus basalis (Banks) (43%) was dominant. The tribe Psycodini was most abundant in the sewage-contaminated water while the tribes Pericomini and Tematoscopini were most abundant at the uncontaminated sites.