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ARS Home » Northeast Area » Newark, Delaware » Beneficial Insects Introduction Research Unit » Research » Research Project #429114

Research Project: Evaluation of the Establishment, Dispersal and Impact of Newly Introduced Parasitoids for Biocontrol of the Emerald Ash Borer in Virginia

Location: Beneficial Insects Introduction Research Unit

Project Number: 8010-22000-028-08-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Sep 15, 2015
End Date: Sep 14, 2020

1) Identify new locations for release of parasitoids in western VA followed by systematic releases of the newly introduced agents Spathius galinae and Tetrastichus planipennisi; 2) Monitor and evaluate the establishment success of both parasitoid species and impact on the target pest populations; 3) Assess dispersal capabilities of both parasitoids following their release upon successful establishments in the release sites.

We will visit all known EAB infestations within forest settings in western or central VA and southern West Virginia. The status of these infestations will be characterized. Typical forest measurements such as ash species, tree age, species composition, % ash, size of the infestation, and estimated time since trees first became infested. Sites with a sufficient number of uninfested ash trees within close proximity, will be considered for use in the project. Site selection will follow the guidelines recommended by Gould et al. (2012). This includes > 25% ash component and infestations with low-moderate population densities of EAB. Spathius galinae and T. planipennisi will be released according to specific guidelines described in Gould et al. (2012). Timing of releases will be appropriate for when early instar EAB larvae are present in the trees. A central plot location will be identified. Both species will be released at the same time. Parasitoids will be released by hanging small infested logs from the central release tree. The number of parasitoids released will depend on their availability and will be similar in number between species. Two techniques will be used to sample for parasitoids. The first technique is not destructive and will involve the deployment of yellow pan traps (Bauer et al. 2013) in cardinal directions at distances of 25, 50, 75, and 100 m during July and August, one year post-release. In the 2nd year, traps will extend beyond these distances if ash trees are present. A second technique is destructive and involves cutting down trees, bucking the trunk into 1 m sections, and then searching for overwintering EAB larvae. Parasitized larvae will be noted, then collected and brought back to the lab to rear out the parasitoids. Four trees will be chosen within a 30 m distance from the release tree. In year 2 we will sample trees up to 60 m from the release tree. In year 3, we will extend the sampling to 90 m. For all 1 m bolts sampled, bark thickness will be measured, allowing us to assess parasitism by species as a function of bark thickness.