Determination of Host Specificity of the Alligatorweed Flea Beetle, Agasicles n. sp., with Radioisotopes1

Host specificity was determined with 3 experimental designs. each replicated. Three plant species, Alternanthera phylloxerroides (Mart.) Griseb., Atriplex patula L. var.hastate (L.) A. Gray, and Polygonum punctatum Ell., that were known to invoke different degrees of feeding in alligatorweed flea beetles, Agasicles n. sp., were supplied labeled phosphorus (via the roots) as P32O4H2K, nearly carrier free (~20 µ/Ci in 65 ml,~10-7M), during a 74.5-hr period prior to feeding. Plants thus prepared were offered to the beetles. In the 3 tests the results confirmed the host specificity of the beetle to alligatorweed, and a ratio of feeding to nibbling was determined from the radio assays.