Submitted to: Society for Invertebrate Pathology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 8/25/2001
Publication Date: N/A
Technical Abstract: A serious limitation to the commercial use of fungal propagules as biocontrol agents has been the lack of available methodology for producing desiccation-tolerant blastospores with good storage stability or shelf-life. We have evaluated factors that influence the production, drying, and stabilization of blastospores of the entomopathogenic fungus Paecilomyces fumosoroseus (Pfr). When appropriate sources and concentrations of nitrogen are used in the liquid fermentation medium, high yields of blastospores [1-2 x 10(9) spores/mL] were produced after a 48-hour fermentation. Pfr blastospore survival rates of 70-90% were obtained after freeze- drying or air-drying spore preparations to moisture levels below 4%. Pfr blastospores formulated with diatomaceous earth or kaolin clay showed improved storage stability when these preparations were air-dried with moist air (RH > 60%). Freeze-dried Pfr blastospore preparations also showed excellent drying survival and storage stability. Storage temperatures of 4C to -20C maximized the shelf-life of air- or freeze-dried Pfr preparations with some freeze-dried preparations showing no significant loss in viability after 12 months' storage. These studies have demonstrated that effective methods can be developed for producing and stabilizing Pfr blastospores if nutritional and environmental factors are considered. The dried Pfr blastospore preparations produced in these studies have shown excellent biocontrol efficacy against the silverleaf whitefly (Bemisia argentifolii).