Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 13, 1996
Publication Date: N/A
Interpretive Summary: The corn earworm and tobacco budworm are two important pests of numerous crops in the United States and world-wide. One means of controlling these pest insects is by collecting and then releasing their natural enemies. But, before beginning an active release program, one has to determine which natural enemies would offer the most efficient control of crop-damaging insects. In order to accomplish this, a previously devised method was used. This method employs monoclonal antibodies to test the stomach contents of potential predators for the presence of proteins derived from specific pest insects. In the present study, we sought to identify the proteins recognized by antibodies raised to corn earworm and tobacco budworm eggs. Our results indicated that both antibodies recognized an egg protein known as vitellin. The antibodies varied in their ability to recognize vitellins from various insect species, with one antibody only recognizing vitellin of the corn earworm and the second antibody only recognizing vitellins of the Heliothis/Helicoverpa complex (which include the corn earworm and tobacco budworm, as well as other important pest insects). Neither of the antibodies strongly recognized the vitellins of insects tested from outside this complex. Additionally, the antibodies were found to recognize vitellin's precursor protein from moths, which plays a major role in egg development. Thus, these two antibodies will serve as important tools for evaluating the efficiency of potential insect predators and for determining possible target sites for the disruption of insect development.
Technical Abstract: Studies were performed to identify and partially characterize the antigens recognized by monoclonal antibodies raised against eggs of Helicoverpa zea (Boddie) and Heliothis virescens (Fabricius) (Lepidoptera:Noctuidae). Through western blot analysis with native PAGE, the antigens for both of these antibodies were determined to be vitellin. Western blotting with SDS-PAGE indicated that the determinant for the antibody produced to H. virescens eggs (HVE-1) was exclusively found on the large molecular weight apoprotein of vitellin, apoVn-I. The determinant for the antibody to H. zea eggs (HZE-1) was not detected by western blotting with SDS-PAGE, indicating that its determinant was not recognizable after holoprotein dissociation. Further electrophoretic analyses indicated that the apparent molecular weights of the native vitellins ranged from 472 to 522 kd, and that those of their apoproteins ranged from 164 to 169 kd (apoVn-I) and 45 to 47 (apoVn-II). The species and stage specificity of the antibodies was also elucidated. The HZE-1 antibody was found to be specific for eggs of H. zea and two Old World relatives (Helicoverpa armigera (Hubner), Heliothis punctigera (Wallengren)), but did not recognize eggs of H. virescens, Heliothis subflexa (Grote), or three genera of non-heliothine noctuids. The HVE-1 antibody recognized eggs from all Helicoverpa/Heliothis species tested, but not from those of the non- heliothine nocutids. Neither antibody cross-reacted with native proteins from homogenates or hemolymph of H. zea and H. virescens larvae or pupae. Western blots performed on adult hemolymph indicated that the antibodies recognized H. zea vitellogenin, vitellin's precursor.