BIOLOGICAL-CONTROL OF THE ZEBRA MUSSEL DREISSENA-POLYMORPHA AND THE SNAIL BIOMPHALARIA-GLABRATA, USING GRAMICIDIN-S AND GRAMICIDIN-D AND MOLLUSCICIDAL STRAINS OF BACILLUS

Applications of Final Whole Culture (FWC) or primary powder material f rom strains of each of four Bacillus species (B. alvei, B. brevis, B. circulans, B. laterosporus) used singly, as well as the antibiotics Gr amicidin S (GS) and Gramicidin D (GD) used singly, were found to be mo lluscicidal against several life cycle stages of the zebra mussel Drei ssena polymorpha. Combinations of the bacterial material with either G S or GD were either additive (for GS) or antagonistic (for GD). The sm aller the life cycle stage of the animal, the more sensitive it was to either the bacterial or antibiotic agent. The veliger stage was parti cularly sensitive to each agent, with the molluscicidal effect being m ore rapid in the veliger (5 h) than in the adult (6 days). The mollusc icidal effects of these agents (at 1-100 mu g ml(-1)) against the veli ger stages of the zebra mussel were comparable to the activity of B. t huringiensis and B. sphaericus against their target organisms. These a gents used singly were also active against small adult Biomphalaria gl abrata, the snail vector of schistosomiasis (eg at tenths of mu g ml(- 1) of GS).