Biological control of Bemisia tabaci with fungi

Recent advances in production, formulation, and application of insect pathogenic fungi have resulted in improvements in longstanding whitefly mycoinsecticide products based on Verticillium lecanii, and development and registration of several new products based on Paecilomyces fumosoroseus and Beauveria bassiana. These products have the capacity to suppress and, in some instances, provide good control of whiteflies in both greenhouse and field crops. However, numerous factors continue to impede the commercial development of fungi as whitefly biological control agents. These include slow action, poor adulticidal activity, potentially negative interactions with commonly used fungicides, relatively high cost, limited shelf life, and dependence on favorable environmental conditions. Development of methods and strategies for overcoming these limitations has progressed, however, and various practices that enhance mycoinsecticide efficacy have been identified. Principal ecommendations include: (1)initiating treatments against the early stages of the pest to prevent population buildup, (2)targeting pest populations developing under moderate environmental conditions (e.g., during spring or fall growing seasons), (3)selecting crops amenable to multiple, highly efficient spray applications, and (4)applying fungi asynchronously with incompatible fungicides. Commercial markets for these products have been slow to develop and remain unstable in the face of strong competition from less costly, highly efficacious chemical insecticides. Nevertheless, continuing problems with chemical insecticide resistance and environmental and food contamination support continued development of fungi as relevant tools in the whitefly biological control arsenal.