Activity of Bacillus thuringiensis var. israelensis on Bradysia coprophila (Diptera: Sciaridae)1

The effects of Bacillus thuringiensis var. israelensis (H-14) (Bti) were tested against the fungus gnat, Bradysia coprophila, in the laboratory and the greenhouse. The LC50 of Bti to 9-day-old larvae was 50.9 IU/cm2. When insects were exposed to Bti (50.9 IU/cm2) during the period from egg to pupa, only 8% of the insects survived compared to 84% survival of insects treated only with water. Sublethal doses of Bti appeared to retard development of late instars. B. thuringiensis var. kurstaki had minimal activity on this insect when compared to Bti. In the greenhouse, Bti was also toxic to larvae of B. coprophila.