Parasitoid mark-release-recapture techniques -: II.: Development and application of a protein marking technique for Eretmocerus spp., parasitoids of Bemisia argentifolii

In this study, we validate and apply techniques for marking and capturing small parasitoids of the silverleaf whitefly, Bemisia argentifolii Bellows & Perring [= B. tabaci (Gennadius), strain B] for mark-release-recapture (MRR) studies. The marker is the purified protein, rabbit immunoglobulin G (IgG), which was applied externally by topical spray or internally by feeding. Marked parasitoids were then assayed using a sandwich enzyme-linked immunosorbent assay (ELISA) for the presence of the protein marker using an antibody specific to rabbit IgG. Virtually all of the externally marked Eretmocerus sp. (Ethiopia, M96076) (98.0%) contained enough rabbit IgG to be easily distinguished from unmarked parasitoids, regardless of the amount of protein applied or the post-marking interval. A field MRR study was then conducted to examine the dispersal characteristics of E. emiratus Zolnerowich & Rose. Parasitoids marked externally and internally with protein were released on three separate trial dates into the center of a cotton field bordered by cantaloupe and okra. Overall, a total of 1388, 637, and 397 marked and unmarked wasps were captured in suction traps during each trial, respectively with the majority of parasitoids captured between 0600 and 0800 h. Furthermore, even though we released an equal proportion of males to females, our traps consistently contained more males. Our results suggest that there are gender-specific differences in the dispersal behavior of E. emiratus. Almost 400 of the captured parasitoids collected during the three release trials were positively identified for the presence of the protein marker. The distribution of the marked parasitoids revealed two distinct patterns. First, almost all of the marked parasitoids recaptured in the cotton plot were in suction traps at or adjacent to the release site. Second, marked parasitoids were recaptured more frequently in distant traps located in the cantaloupe plot than in distant traps located in the cotton and okra plots, thus suggesting that the parasitoids were moving toward the cantaloupe plots.