Laboratory and field evaluation of exotic parasitoids of Bemisia tabaci (Gennadius) (Biotype "B") (Homoptera: Aleyrodidae) in the lower Rio Grande valley of Texas

We evaluated a total of 38 exotic and 2 native parasitoid populations of the sweetpotato whitefly Bemisia tabaci (Gennadius) (Biotype "B") (Homoptera: Aleyrodidae) (= silverleaf whitefly, Bemisia argentifolii Bellows and Perring), using laboratory and held experiments. Numbers of B. tabaci parasitized were counted in sleeve cages on cantaloupe melons (Cucumis melo L. cv "Perlita"), cotton (Gossypium hirsutum L. cv "Delta Pine 51"), and broccoli (Brassica oleracea L. cv "Patriot"). Highest attack rates were found for Encarsia nr. pergandiella (Hymenoptera: Aphelinidae) (Brazil) and Eretmocerus mundus Mercet (Spain) on melons; Eretmocerus sp. (Pakistan) on cotton; and Eretmocerus mundus (Spain) on broccoli. In the laboratory, these three exotic parasitoids attacked significantly greater numbers of hosts than the native species of Encarsia pergandiella Howard and Eretmocerus tejanus Rose and Zolnerowich. Selected exotic parasitoids were evaluated in the field using sleeve cages on melons, cotton, and kale (Brassica oleracea L. cv "Siberian kale"). Eretmocerus spp. from Spain and India performed well, in all crop types. Encarsia nr. pergandiella (Brazil) performed well on melons, but not on kale or cotton. Selected exotic parasitoids were released at various sites throughout Hidalgo County in the Lower Rio Grande Valley of Texas. Of 29 populations released in the held, eleven were later recovered. Two Eretmocerus species (Spain and Pakistan) were commonly recovered throughout the evaluation period. This information will be used to prioritize the parasitoid cultures for mass rearing and release in biocontrol-based IPM programs against B. tabaci.