Tritrophic Interactions Among Host Plants, Whiteflies, and Parasitoids

Abstract

Effects of cotton, Gossypium hirsutum L.; green bean, Phaseolus vulgaris L.; and sweet potato, lpomoea batatas (L.) Lam.; on mortality and development of sweetpotato whitefly, Bemisia tabaci (Gennadius) biotype B; bandedwinged whitefly, Trialeurodes abutilonea (Haldeman); and greenhouse whitefly, T. vaporariorum (Westwood); and on the key biological parameters of an exotic parasitoid species, Eretmocerus mundus Mercet, and an indigenous parasitoid, Encarsia pergandiella Howard, were compared in the laboratory. Cotton was most suitable for sweetpotato whitefly, and bean was most suitable for greenhouse whitefly. No significant differences were found between these two whitefly species on sweet potato. Preimaginal mortality of sweetpotato whitefly on cotton was 35.2% versus 77.3% of greenhouse whitefly. Developmental time of sweetpotato whitefly was significantly shorter (17.5 days) than that of greenhouse whitefly (23.2 days). The mortality and developmental time of bandedwinged whitefly did not differ on the different host plants. Parasitism by Er. mundus was greatest in sweetpotato whitefly and least in greenhouse whitefly when both whiteflies were reared on cotton. Parasitism of bandedwinged whitefly was intermediate. Parasitism by En. pergandiella was significantly greater than that by Er. mundus attacking the same whitefly species reared on bean or cotton, except parasitism of sweetpotato whitefly. Emergence of Er. mundus was greatest from sweetpotato whitefly on cotton, and least for bandedwinged whitefly on bean. Emergence of En. pergandiella was significantly greater than that of Er. mundus among host plants and whitefly species except sweetpotato whitefly.