Insecticide activity of surfactins and iturins from a biopesticide Bacillus subtilis Cohn (S499 strain)

Surfactin C14, surfactin C15, and iturin C15 are lipopeptides purified from Bacillus subtilis (S499 strain). They were incorporated into the artificial diet of the fruit fly Drosophila melanogaster to assess their potential insecticidal activities. Surfactins with long fatty acid chains (C14 and C15) had an insecticidal effect on the fruit fly, D. melanogaster. On the contrary, iturin was not toxic to D. melanogaster. At 100 ppm, surfactin C14 and C15 caused 85.4 and 92.6% adult mortality, respectively, after a one-day exposure. F1 progeny fly emergence inhibition by C14 and C15 were 79.8 and 91.3%, respectively. To check whether the biocide activity of lipopeptides was due to their surface-active properties, detergent Triton X100, SDS, CTAB, and Tween 80 were tested. No adult mortality was recorded with the detergents but Triton X100 and SDS showed F1 progeny emergence inhibition similar to that of surfactins. We showed that there was a dose-response activity with surfactin C15