Laboratory evaluation of six species of entomopathogenic fungi for the control of the house fly (Musca domestica L.), a pest of intensive animal units.

The effectiveness of six species of entomopathogenic fungi for the control of adult and larval stages of the house fly Musca domestica was assessed in the laboratory. Metarhizium anisopliae and Tolypocladium cylindrosporum were the pathogens most virulent to house fly larvae. Tolypocladium cylindrosporum prevented adult emergence at doses of 1 x 10(8), 10(7), 10(6), and 10(5) conidia/ml, and M. anisopliae prevented emergence at 1 x 10(8) and 10(7) conidia/ml, with only 1.0 and 16% emergence at 1 x 10(6) and 1 x 10(5) conidia/ml, respectively. Adults were susceptible to aqueous suspensions of conidia of all species tested; however, M. anisopliae was the most pathogenic in the shortest time, giving 100% mortality in 6 days. Five vegetable oils, one mineral oil, and two adjuvants were screened as potential carriers of M. anisopliae conidia. Linseed and soya bean oil were the most effective carriers, with complete mortality achieved in only 3 days, resulting in at least a x2 decrease in the time to 100% kill compared with the equivalent aqueous suspension of conidia. Linseed, soya bean, and cotton seed oil were also compared using a dose-response bioassay. Linseed oil was the most effective carrier of M. anisopliae, giving 100% kill in 3 days at a dose of 1 x 10(5) and in 6 days at 1 x 10(3) conidia/fly. The implications of these results in relation to house fly control and to future research are discussed.