Location: Beneficial Insects Introduction Research Unit
Project Number: 8010-22000-031-001-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 15, 2016
End Date: Jun 15, 2022
Objective:
1. Identify new locations for release of parasitoids in Delaware and adjacent states (such as MD, PA and/or NJ) followed by systematic releases of introduced biocontrol agents such as Oobius agrili., Spathius galinae and/or Tetrastichus planipennisi.
2. Monitor and evaluate the establishment success of the released parasitoid species and impact on the target wood-boring pest populations.
3. Evaluating the impact of biotic and abiotic factors on parasitoid dispersal, spread, establishment and control efficacy following their release in the field at different geographic regions.
Approach:
We will visit all known EAB infestations within forest settings in Delaware and adjacent states (e.g., MD, PA and/or NJ). 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.
All parasitoids 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 or eggs are present in the trees. A central plot location will be identified. Parasitoids will be released by hanging small infested logs (for larval parasitoids) or sentinel egg papers (for egg parasitoids) from the central release tree. The number of parasitoids released will depend on their availability and will be similar in number between species.
Two types of techniques will be used to sample for parasitoids. The first technique is not destructive and will involve visual search of EAB eggs and parasitized eggs by removing the loose bark of EAB-infested tree trunks or by using sentinel EAB eggs produced in the lab to monitor field parasitism by the egg parasitoids. A second technique is destructive and involves cutting down trees, bucking the trunk into 1 m sections, and then searching for overwintering EAB larvae and associated parasitiods. 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.
In addition, we will conduct both laboratory and field studies to evaluate the impact of different biotic (e.g., parasitoid age and diapauses pattern) and abiotic factors (e.g., temperature and photoperiod) on parasitoid dispersal, spread, phenology, establishment and control efficacy.
