Browsing by Author "Ragozzino, Max"

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    Differences in Early Season Emergence and Reproductive Activity Between Spathius agrili (Hymenoptera: Braconidae) and Spathius galinae, Larval Parasitoids of the Invasive Emerald Ash Borer (Coleoptera: Buprestidae)
    Ragozzino, Max; Meyer, Ryan; Duan, Jian; Slager, Ben; Salom, Scott M. (2020-04)
    Both Spathius agrili Yang and Spathius galinae Belokobylskij and Strazanac are host-specific parasitic wasps introduced for biological control of emerald ash borer in North America. Spathius agrili is native to northeastern China and S. galinae comes from a more northern, colder climate in the Russian Far East. Their origin may lead to differing abilities to adapt to climate and their host in North America. We conducted both field and laboratory experiments to determine the timing of early season emergence and synchronization of each parasitoid species to their host in the United States, and if manipulating prerelease conditions could affect emergence time. A cold acclimatization treatment prior to parasitoid emergence was assessed and compared with untreated control group reared with standard rearing protocols. Stands of naturally emerald ash borer-infested ash were sampled at two locations in Virginia throughout the experiment to determine when the parasitoid-susceptible life stage (third to fourth instar) occurred. Untreated S. galinae emerged approximately 2 wk earlier than any other cohort, whereas cold acclimatized S. galinae emerged later than any other cohort. Emergence time of S. agrili was unaffected by cold acclimatization. Cold acclimatization treatment did not affect the parasitism rate of either species, nor did it have multigenerational effects. Emergence time of the subsequent generation of S. agrili was delayed by cold acclimatization treatment, whereas S. galinae experienced no multigenerational effects. At Virginia field sites, susceptible EAB larvae were present during the emergence time of all four groups of parasitoids. Untreated S. galinae had the least overlap with any susceptible EAB larvae.
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    Interspecific Competition Between Idiobiont Larval Parasitoids of Emerald Ash Borer
    Ragozzino, Max; Duan, Jian; Salom, Scott M. (2021-07)
    New associations between parasitoid species is common in biological control with interactions ranging from coexistence to competitive exclusion. Spathius agrili and Spathius galinae, native to North East Asia, are two host-specific idiobiont larval parasitoids of the invasive emerald ash borer Agrilus planipennis that do not overlap in their native ranges but have been recently introduced to the United States for biocontrol of A. planipennis. We conducted laboratory experiments to determine the results of competition between these two species. Competition between parasitoid larvae on a single host (intrinsic competition) and competition between adult parasitoids for oviposition sites (extrinsic competition) were evaluated. Successful multiparasitism did not occur in any intrinsic trials. Extrinsic competition favored S. agrili, but S. galinae was not excluded. Competition lowered parasitism rates for both species, but overall parasitism was not lowered.
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    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
    Ragozzino, Max; Duan, Jian J.; Salom, Scott M. (Elsevier, 2021-09-01)
    Emerald ash borer (EAB), Agrilus planipennis is a buprestid species native to Asia, where it is a pest of ash trees, Fraxinus spp. Since 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. This study evaluates 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 under no-choice conditions. EAB larvae can be successfully parasitized in white fringe tree under laboratory conditions. These results indicate that S. agrili and S. galinae have potential to attack EAB larvae infesting white fringe tree.