The potential of Dicyphus hesperus Knight as a predator of greenhouse whitefly, Trialeurodes vaporariorum (Westwood), and two-spotted spider mites, Tetranychus urticae Koch, was assessed in the laboratory and in a tomato greenhouse. D. hesperus adults fed readily upon both pest species in the laboratory, and nymphs completed development from egg to adult on either whitefly or mites. Whitefly, however, were a superior food for growth and development of D. hesperus compared to mites. Development time was shorter and resulting adult body size was larger for nymphs reared on whitefly compared to those reared on mites. In a greenhouse release, adults oriented to and oviposited on whitefly-infested sentinel plants but did not orient to mite-infested sentinel plants. D. hesperus adults oviposited on greenhouse tomatoes and their progeny completed development in a greenhouse in which both whitefly and mites were present. The results are discussed as they relate to the use of D. hesperus for biological control of pests of greenhouse vegetables.
