Emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) is a species of wood boring beetle which feeds on the inner bark of ash trees, Fraxinus spp., and white fringe tree, Chionanthus virginicus L. In North America emerald ash borer feeding damages the trees vascular system, killing the tree in 1-6 years after initial infestation. Emerald ash borer's native range is north east China, the Russian Far East, and the Korean peninsula. In the mid-1990s emerald ash borer was accidentally introduced to Michigan from the Hebei and Tianjin city province regions of China. Since then, due to human-aided transport and natural spread, emerald ash borer now infests 35 states and five Canadian provinces. Studies in to Asia discovered several species of parasitic wasps which feed and reproduce on emerald ash borer; four of these species were approved for release in the United States. Three species which attack emerald ash borer larvae Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae), Spathius agrili Yang (Hymenoptera: Braconidae), and Spathius galinae Belokobylskij and Strazanac (Hymenoptera: Braconidae), and one species which utilizes emerald ash borer eggs, Oobius agrili Zhang and Huang (Hymenoptera: Encyrtidae). This research focuses on the control of emerald ash borer using the three larvae-utilizing species of parasitic wasp. The first objective of this research focuses on the synchrony of emerald ash borer larvae with the early spring emergence of S. agrili and S. galinae. The first objective also assessed how two different cold temperature treatments changed the emergence timing, and health of the wasps. The second objective assessed to determine the effects of competition between S. agrili and S. galinae when they were exposed to a single emerald ash borer larvae sequentially, and simultaneously. When exposed sequentially, the first wasp held the competitive advantage, but when exposed simultaneously S. agrili had a small advantage, but did not completely exclude S. galinae. The third objective focused on the potential for two larval parasitoids, S. agrili and S. galinae to parasitize emerald ash borer larvae in the novel host plant white fringe tree. We determined that both parasitoids are capable of finding and parasitizing emerald ash borer larvae within a non-ash host. Finally, we located 13 stands of emerald ash borer infested ash in Virginia and North Carolina in order to determine its life cycle, and overwintering life stage. We determined that emerald ash borer overwinters at different life stages, and has a more complex life cycle than previously reported. Additionally, all three species of larvae-utilizing parasitic wasp were recovered at field sites at least 1 year after release. These results all show promise for the biocontrol program, and indicate that biocontrol of emerald ash borer could be successful in Virginia and North Carolina. / Doctor of Philosophy / Emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) is a wood boring beetle which feeds on the inner bark of ash trees, Fraxinus spp., and white fringe tree, Chionanthus virginicus L. In the mid-1990s emerald ash borer was accidentally introduced to Michigan from the Hebei and Tianjin city province regions of China. Since then, due to human-aided transport and natural spread, emerald ash borer now infests urban and natural forests in 35 states and five Canadian provinces. North American ash trees did not evolve with emerad ash borer, and have little resistance to their attack. A North American ash or white fringe tree attacked by emerald ash borer dies in 1-6 years if left untreated. Systemic insecticide treatments exist, but require annual treatment and are less effective than initially hoped. Additionally, systemic insecticides are impractical to apply to forest ecosystems. Researchers traveled to the Asia, and discovered several species of parasitic wasps which attack emerald ash borer. After years of efficacy and host-exclusivity testing four species were released in the United States. Three species which exclusively utilize emerald ash borer larvae Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae), Spathius agrili Yang (Hymenoptera: Braconidae), and Spathius galinae Belokobylskij and Strazanac (Hymenoptera: Braconidae), and one species which utilizes emerald ash borer eggs, Oobius agrili Zhang and Huang (Hymenoptera: Encyrtidae). My research focuses on the control of emerald ash borer using the three larvae-utilizing species of parasitic wasp. Chapter two focuses on the life cycle of emerald ash borer larvae, S. agrili and S. galinae during the early spring. We determined that both parasitoid species have similarly timed life cycles as EAB, indicating a good climate match in Virginia. Chapter three describes the interactions between S. agrili and S. galinae when competing for EAB larvae. We determined that the first species to attack the larvae has the advantage; and when adult wasps competed to find a larvae neither species completely dominated the other. The third objective focused on the potential for two larval parasitoids, S. agrili and S. galinae to parasitize emerald ash borer larvae in the novel host plant white fringe tree. We determined that both parasitoids are capable of finding and parasitizing emerald ash borer larvae within white fringe tree. Finally, we located 13 stands of emerald ash borer-infested ash in Virginia and North Carolina in order to determine its life cycle, and overwintering life stage. We determined that emerald ash borer overwinters at different life stages, and has a more complex life cycle than previously reported. Additionally, all three species of larvae-utilizing parasitic wasp were recovered at field sites at least 1 year after release. These results all show promise for the biocontrol program, and indicate that biocontrol of emerald ash borer could be successful in Virginia and North Carolina.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/107265 |
| Date | 02 July 2020 |
| Creators | Ragozzino, Max Louis |
| Contributors | Entomology, Salom, Scott M., Brewster, Carlyle C., Walters, Jeffrey R., Duan, Jian Jun, Kring, Timothy Joseph |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf |
| Coverage | Virginia, North Carolina, United States |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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