Influence of two species of dung beetles on larvae of face fly.

Laboratory experiments were carried out to assess the influence of two dung beetles Onthophagus taurus Schreber and Onitis alexis Klug, on larvae of face fly, Musca autumnalis DeGeer, developing within the same cowpats. Increasing densities of both teneral and mature O. taurus caused corresponding decreases in the survival of fly larvae and the size of emerging adults. In contrast, survival of face fly larvae was independent of the density of teneral O. alexis . but quite dependent upon the density of mature beetles. This difference was related to the amount of dung buried by beetles in the two age-classes. The earlier both species of beetles colonized cowpats relative to face fly, the more face fly was adversely affected. When reared with either species of beetle alone, mortality among fly larvae was greater than could be attributed to starvation. When reared with both species, both the survival and size of face fly larvae were lower than predicted by the combined effects of each beetle alone. Implications for future efforts to manage the face fly with dung-burying scarabs are discussed.