Development of a Spray-drying Technique for Submerged Spores of Entomopathogenic Fungi

Abstract

The stability of blastospores or submerged conidia of entomopathogenic fungi is one of the key problems associated with the practical use of fungal biopreparations. A spray-drying technique was developed which allows the drying of blastospores and/or submerged conidia, here called submerged spores, without a significant loss of viability and with only a slight delay in eY cacy. The method was tested successfully using the fungal species Metarhizium anisopliae , M. flavoviride, Beauveria bassiana and Paecilomyces fumosoroseus . For all experiments, a laboratory spray dryer was used. The optimum inlet and outlet temperatures were found to be 64 2oC and 48 2oC respectively. The best protective agent for submerged spores was skimmed milk powder at concentrations of 10 or 20%. The addition of sugars, especially 2.5% sugar-beet syrup, slightly improved the viability after spray-drying. Submerged spores of eight isolates of M. anisopliae, M. flavoviride, B. bassiana and P. fumosoroseus were suspended in 20% skim...