Efficacy of Beauveria bassiana on colonized millet seed as a biopesticide for the control of shore flies

Abstract

Shore flies (Scatella stagnalis) have been implicated as an aerial vector of several soilborne plant pathogens of greenhouse crops. A strain of Beauveria bassiana (Bb), isolated from a shore fly cadaver, was evaluated as a biopesticide for the control of shore flies. Bb was grown on autoclaved millet seed for 2 weeks, air-dried at 24°C for 7 days and stored in paper bags. Dried Bb-colonized millet seeds were broadcast on the surface of pots containing potting medium naturally-infested with larvae and pupae or pots infested only with adult flies. Controls consisted of insect-infested pots amended with autoclaved millet seeds. Pots of the same treatment were placed in insect-proof screen cages. At daily intervals for 15 days, adult fly populations were recorded in each cage. In cages initially containing only larvae and pupae, adult fly populations in the cantrol (no Bb) treatment reached a final population of 70 adults on day 15. In contrast only two adult flies were observed in the Bb-treatment. In cages containing only adult shore flies, the entire population was dead within 10 to 12 days in the Bb-treatment. In the absence of Bb, 65% of the initial population of adults was still alive on day 12.