Host-feeding of three parasitoid species on Bemisia tabaci biotype B and implications for whitefly biological control

Parasitoids in the genera Encarsia and Eretmocerus (Hymenoptera: Aphelinidae) are important biological control agents of whiteflies through their reproductive as well as host-feeding activities. The feeding capacities of female parasitoids of three species with different reproductive strategies [Encarsia sophia (Girault & Dodd), Encarsia formosa Gahan, and Eretmocerus melanoscutus Zolnerowich & Rose] on their host, sweetpotato whitefly, Bemisia tabaci (Gennadius) biotype B (Homoptera: Aleyrodidae), were evaluated on cabbage in a single-instar no-choice experiment in the laboratory and a mixed-instar choice experiment in the greenhouse. In both single- and mixed-instar experiments, significant differences in host-feeding capacities were found among the three parasitoid species. Encarsia sophia exhibited superior capacity of host-feeding compared to E. formosa and E. melanoscutus. In the single-instar experiment, parasitoids fed more on younger (smaller) hosts than older (larger) hosts. In the mixed-instar experiments, all three parasitoid species exhibited a clear preference for feeding on older hosts compared to younger hosts. Total number of whitefly nymphs fed on by E. sophia was approximately three times that of the other two parasitoid species. Whitefly mortality accounted for by host-feeding by E. sophia was up to 59.7%, and, thus, equivalent to parasitization. The significance of host-feeding of E. sophia for biological control of B. tabaci is discussed.