BLACK FLIES (DIPTERA: SIMULIIDAE) OF EAST-CENTRAL SASKATCHEWAN, WITH DESCRIPTION OF A NEW SPECIES AND IMPLICATIONS FOR PEST MANAGEMENT

A 5-year study of the black flies of east-central Saskatchewan revealed 21 species, including Simulium incognitum sp.nov. Chromosomal and ecological evidence for reproductive isolation is presented for this new species, formerly known as S. venustum Say CC4, and S. venustum Say CC. All 21 species in the study are associated with productive streams and rivers. As many as nine of these species might comprise the pest assemblage harassing livestock. The major pest, S. luggeri Nicholson and Mickel, is cytologically distinct from populations in the eastern United States on the basis of a two-step, Y-linked inversion in the IIS chromosomal arm. Simulium luggeri is the only livestock pest that breeds almost solely in large streams and rivers. The other eight probable pests breed entirely or partly in streams less than 10 m wide, often below beaver dams, suggesting that management efforts should specifically target these sites.