BIOLOGY AND ECOLOGY OF COTTON PESTS EMPHASIZING MANAGEMENT OF BOLL WEEVILS
Title: Tritrophic interaction among host plants, whiteflies, and parasitoids
Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 14, 2009
Publication Date: December 15, 2009
Citation: Greenberg, S.M., Jones, W.A., Liu, T. 2009. Tritrophic interaction among host plants, whiteflies, and parasitoids. Southwestern Entomologist. 34(4):431-445.
Interpretive Summary: The three whitefly species, Bemisia tabaci, Trialeurodes vaporariorum, and Trialeurodes abutilonea, are widespread pests of the most important vegetable, field, and ornamental crops around the world. Insecticides can provide control but are expensive and misuse often results in resistance development. Integrated pest management programs, including the use of more promising parasitoids (Eretmocerus mundus, Eretmocerus eremicus, and Encarsia pergandiella) which reduce crop losses by killing whiteflies, should be the main strategy of crop protection. The successful utilization of parasitoids will depend on our knowledge of many factors, including tritrophic interactions among host plants, insects, and parasitoids. We studied the effects of beans, cotton, sweet potato, and tomatoes on the mortality and development of the three whitefly species, and then compared biological attributes of parasitoids when reared on whitefly species maintained on different host plants. Knowledge of the interrelationship between host plants, whiteflies, and their parasitoids is critical in developing rearing techniques, making decisions in augmentative release trials, developing predictive models, and understanding the mechanisms involved in parasitoid competition. Ultimately, Er. Eremicus was recommended to producers as a promising species for B. tabaci and T. vaporariorum management, especially in greenhouses. These findings will make utilization of parasitoids for management of whiteflies more practical. Such control will reduce the need for additional insecticide use and associated environmental problems.
Laboratory experiments were conducted to compare effects of cotton, bean, sweet potato, and tomato on the mortality and development of Bemisia tabaci (Gennadius) biotype B, Traileurodes abutilonea (Haldeman), and T. vaporariorum (Westwood) and on the key biological parameters of an exotic parasitoid species, Eretmocerus mundus Mercet, and two indigenous parasitoid species, Er. Eremicus Rose and Zolnerowich and Encarsia pergandiella Howard. Cotton was most suitable for B. tabaci, and bean was the most suitable for T. vaporariorum. Sweet potato and tomato did not show significant differences on these two whitefly species. Total preimaginal mortality of B. tabaci on cotton was 35.2% versus 77.3% of T. vaporariorum. Development time for B. tabaci was significantly shorter (17.5 d) than for T. vaporariorum (23.2 d). The T. abutilonea mortality and development time was not dependent on the host plant. Eretmocerus mundus parasitism was highest on B. tabaci, while the lowest was on T. vaporarium when both whiteflies were reared on cotton. Results for T. abutilonea were intermediate. Encarsia pergandiella parasitism was significantly higher than those by Er. Mundus attacking the same whitefly species reared on bean or cotton, except parasitism in B. tabaci. Eretmocerus mundus emergence rate was highest in B. tabaci on cotton, and the lowest in T. abutilonea on bean. Encarsia pergandiella emergence was significantly higher than Er. Mundus among whitefly species and host plants except B. tabaci. Er. eremicus performed similarly on both whitefly species on tomato.