Bemisia argentifolii (Homoptera : Aleyrodidae) attacking species of medicinal herbal plants

Research was conducted on the production potential of selected medicinal he rbal plant species as new crops suitable for cultivation in South Carolina. 'Whiteflies (Bemisia argentifolii Bellows & Perring) were found in an expe rimental production field infesting five perennial species of medicinal her bal plants [feverfew, Tanacetum parthenium (L.) Schultz-Bipontinus; St. Joh n's wort, Hypericum perforatum L.; purple coneflower, Echinacea pallida (Nu ttall) Nuttall and E. purpurea (L.) Moench; and common valerian, Valeriana officinalis L.]. This article reports on whiteflies attacking and developin g on these plant species. Density of whitefly nymphs was highest (mean = 2. 3/cm(2)) on the second fully expanded leaf on the epical meristem of E, pur purea as compared with the same leaf position on the other plant species wh ere average whitefly density ranged from 0.1 to 0.6 nymphs per square centi meter from late November 1998 through January 1999. Similarly, adult captur e on sticky cards was high (mean = 123 whiteflies per card) in plots of E. purpurea compared with plots of the other four species (mean = 8 to 20 whit eflies per card per species), and adult counts were elevated in the highest (440 kg N/ha) of three fertility rates in E, purpurea. Moreover, laborator y tests agreed with the observation of a higher population of B. argentifol ii on E. purpurea compared with the other four plant species. The whitefly completed development on all five plant species, and whitefly-associated pa rasitoids emerged from field-leaf samples of each plant species.