Prospects of using entomopathogenic fungus in development of a biopesticide product with nematicidal activity

Abstract

Abstract Entomopathogenic and nematophagous fungi are the recourse for biological control of phytoparasitic insects or various stages of nematodes. The objective of this work was to evaluate the prospects of using an entomopathogenic fungus strain of Beauveria bassiana to develop a biological product, in native form and immobilized on a carrier, which would possess, among other characteristics, nematicide activity. In culture suspension based on a mixture of milk whey and brewing spent grain liquor, the product showed catalase and cellulolytic activity, as well as high yield of spore-bearing biomass. Insecticidal activity of the fungus has been determined relative to a test-organism - Drosophila melanogaster. Virulence was at 50% with the infective dose of 102 CFU. A method of fungus passaging through organism of an insect is proposed as a way of maintaining biological activity. We have found nematocidal activity of the strain of B.bassianа with regard to a test organism – bacterial-feeding nematodes of the Rhabditidae family. A correlation dependency has been revealed between biological activity in terms of motile stages of nematodes and the concentration of culture suspension containing enzymes, secondary metabolites and native (own) toxins of entomopathogenic fungus. Use of native, undiluted suspension based on the mixture of milk whey and brewing spent grain liquor ensured 100% death of the number of nematodes within 2 day of incubation. The suggested product is a biodegradable carrier-immobilized form of biopesticide developed using spent grain that ensured viability of infectious units of the strain after storage.