Location: Beneficial Insects Introduction Research Unit
Project Number: 8010-30400-001-035-I
Project Type: Interagency Reimbursable Agreement
Start Date: Mar 31, 2026
End Date: Sep 29, 2027
Objective:
The proposed research aims to continue to rear and research a genetic line of the introduced parasitoid Spathius agrili from established sites in Tennessee (or other sites in the southern U.S.) that have been adapted to a warmer climate and may be thus effective for field releases against the invasive emerald ash borer (EAB) in the southern U.S. Specific objectives are:
(1) Continue to maintain and rear the Tennessee colony of S. agrili (established in FY2024) for research and field releases against emerald ash borer in the southern U.S.
(2) Evaluate overwintering diapause, survival and spring emergence phenology of the Tennessee S. agrili vs the original APHIS S. agrili colony and its congener S. galinae in southern U.S.
Approach:
All parasitoid rearing will be conducted in reach-in environmental chambers under normal rearing conditions (~25C, 65% RH, and long day photoperiod – 16:8 hrs L:D) according to procedures described in Dang et al. (2025). We will first need to rear late instar EAB larvae on tropical ash bolts (diam ~1.5 cm x length ~ 15 cm) infested with EAB eggs. Newly emerging female and male wasps of S. agrili will be first hosted together in rearing cages for a week and then exposed to EAB-infested tropical ash bolts for another week. After parasitoid exposure, exposed ash bolts will be moved to clean containers and incubated undernormal rearing conditions for adult emergence (normally 4-6 weeks post exposure).
For Objective 1, we will repeat the rearing procedure described above to produce enough
parasitoids for research needs in Objective 1 as well as program releases in Texas. If additional
samples of S. agrili (F0) are collected from Tennessee in 2026, we will mix the newly collected
S. agrili (F0) with our established colony of Tennessee S. agrili (F15 – 20) and then exposed to
suitable stages of EAB larvae to produce a mixed colony of S agrili. The progeny of this mixed
S. agrili will then be sent to USDA APHIS EAB Rearing Facility in Brighton, MI for massproduction
for field releases against EAB in the southern U.S. Previous transfers of this colony
to the Brighton Rearing Facility were not made due to heavy personnel losses at the facility in
2025. Anticipating the hiring of a new rearing technician at the facility specifically for the TN S.
agrili colony, we hope to transfer the colony to Brighton in early 2027.
For Objective 2, ash bolts containing mature (cocooned) larvae of TN S. agrili will be produced
in late fall (September, October, and November) according to procedures described above in
Objective 1 and then shipped to our collaborator at Tarleton State University (Stephenville, TX) for field deployment. At the same time, ash bolts containing the comparable stages of the
original APHIS S. agrili and S. galinae will be produced at the APHIS Brighton EAB biocontrol
facility and shipped to Tarleton State University for field deployment for comparison with TN S.
agrili.