Abstract: Encarsia formosa Gahan (Hymenoptera: Aphelinidae) is the dominant parasitoid of important whitefly species, such as Trialeurodes vaporariorum Westwood and Bemisia tabaci (Gennadius). Most of the Aphelinidae species are small and morphologically similar, and this makes them hard to be identified accurately. In this study, a pair of SCAR (sequence characterized amplified region) primers (EFZZF/EFZZR) which are specific to En. formosa was developed by using other five common Aphelinidae species and four biotypes of B. tabaci as the control. The fragment amplified by these primer pairs was 287 bp in length. Species specificity test showed that all En. formosa specimens were detected with no cross reactions with other aphelinid species, including En. sophia (Girault & Dodd), Eretmocerus hayati Zolnerowich & Rose, Eretmocerus sp., Er. mundus Mercet, Amitus hesperidum Silvertri, or whitefly species including four biotypes (B, Q, ZHJ-1, and ZHJ-2) of B. tabaci as well as T. vaporariorum and Aleurocanthus spiniferus (Quaintanca). Even at the concentration of 7.812 ng/μL DNA, equal to 1/1 600 of a whole female adult of En. formosa, the 287 bp DNA fragment could be detected in all replicates. The technique developed here would be useful for rapid and precise species identification, determination of the host spectrum and more effective utilization of En. formosa.

Key words: Encarsia formosa, Bemisia tabaci, rapid identification, molecular identification, SCAR marker, detection threshold