Location: Beneficial Insects Introduction Research Unit
Project Number: 8010-30400-001-037-A
Project Type: Cooperative Agreement
Start Date: Sep 30, 2026
End Date: Aug 29, 2027
Objective:
Epathius agrili, an EAB biocontrol agent, has been released into ash stands in the southern U.S. (below the 40th parallel) for over 15 years. Only recently (2024), however, has this parasitoid been found to have successfully established long-term self-sustaining populations at one site in Tennessee (thereafter referring to TN S. agrili). The objective of this agreement is to evaluate overwintering diapause, survival and spring emergence phenology of the colonies of S. agrili from Tennessee and original APHIS S. agrili and its congener S. galinae in Texas.
Approach:
Ash bolts containing mature (cocooned) larvae of TN S. agrili will be produced in late fall (Sep-Nov) according to procedures described in Dang et al. (2025) for planned field deployment at Tarleton State University. Bolts containing comparable stages of the original APHIS S. agrili and S. galinae will be produced at the APHIS Brighton EAB biocontrol facility (Brighton, Michigan) or USDA ARS Beneficial Insects Introduction Research Unit (Newark, Delaware) and shipped to Tarleton State University for field deployment for comparison with TN S. agrili.
For field deployment, personnel will follow the same procedure described in Sherr et al. (2023) for setting up ash logs containing late instars of S. agrili or S. galinae larvae inside cocoons in host galleries in Texas and Delaware. Personnel will cut ash logs (~20 cm in length, ~5 cm diameter) with overwintering containers (3.8-L polyethylene terephthalate jars with two, 7.6 cm diameter screened holes) containing the parasitoid larvae on a saturated circular cutout of standard floral foam. A total of 15 overwintering containers (one for each parasitized log) will be established at each site for each treatment, for a total of 45 overwintering containers. Data loggers will be placed inside select jars at each site to estimate mean daily temperature within each site as representation of temperature experienced by each larvae. Photoperiod data will also be collected by personnel from nearby weather stations in both Texas and Delaware.
Following field deployment, personnel will inspect jars weekly at each site throughout the winter and water the floral foam to keep logs from drying out and maintain humidity within the jars. Once emergence begins in Spring 2027, personnel will check jars 2-3 times per work week, measure abundance by species and sex of each parasitoid, and release. Jars will remain affixed to bolts and continue monitoring for emergence into Summer 2027. Once parasitoid emergence stops (at least four weeks after last emergence), overwintered ash logs will be brough back to Tarleton State University or at BIIRU for dissection or peeling. Upon dissection, the stage and fate of all parasitoids (adults emerging, larvae alive and remaining in diapause, or dead) will be recorded.