|RAGOZZINO, MAX - Virginia Tech|
|SALOM, SCOTT - Virginia Tech|
Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/17/2021
Publication Date: 5/20/2021
Citation: Ragozzino, M., Duan, J.J., Salom, S. 2021. Responses of two introduced larval parasitoids to the invasive emerald ash borer (Coleoptera: Buprestidae) infesting a novel host plant, white fringe tree: implication for biological control. Biological Control. 1049-9644. https://doi.org/10.1016/j.biocontrol.2021.104672.
Interpretive Summary: The emerald ash borer (EAB) is a serious invasive forest pest that has killed tens of millions of ash trees in the United States including in mid-Atlantic states such as Virginia. Recently, this invasive beetle was also found attacking the white fringe tree, Chionanthus virginicus, native to mid-Atlantic and southern U.S. We determined whether the beetle's food plant shift from ash to white fringe trees would affect its biocontrol by the two introduced Asian natural enemies (parasitic wasps). Results of the study showed that the two wasps successfully attacked EAB infesting the white fringe tree and showed no preference for EAB larvae infesting ash over white fringe trees. This indicates that the introduced natural enemies of EAB infesting ash trees can also be used for biocontrol of this invasive beetle on white fringe trees.
Technical Abstract: Emerald ash borer (EAB), Agrilus planipennis, is a buprestid species native to Asia, where it is a pest of ash trees, Fraxinus spp. After it was accidentally introduced to the United States in the 1990s, this beetle has become one of the most destructive invasive pests of North American ash trees. In 2015 it was found attacking the white fringe tree, Chionanthus virginicus, indicating the potential for host range expansion. We evaluated the responses of two introduced larval parasitoids, Spathius agrili and S. galinae, to EAB larvae infesting this novel host plant. Third to fourth instar EAB larvae reared with tropical ash in the laboratory were inserted into green ash and white fringe tree bolts. Infested bolts were exposed to gravid females of both Spathius spp. under no-choice and S. galinae under choice testing conditions. No-choice testing indicated no difference in parasitism rate on EAB larvae between white fringe and green ash for either parasitoid species. Two-choice testing with S. galinae also indicated no difference in parasitism rate when green ash was an option. Sex ratio and brood size were unaffected by host substrate for EAB, but both species emerged sooner on EAB in white fringe tree. EAB larvae were successfully parasitized in white fringe tree under laboratory conditions. These results indicate that S. agrili and S. galinae have the potential to attack EAB larvae infesting white fringe tree.