Location: Beneficial Insects Introduction Research Unit
Project Number: 8010-22000-031-074-A
Project Type: Cooperative Agreement
Start Date: Sep 15, 2023
End Date: Aug 31, 2024
Objective:
The emerald ash borer (EAB), Agrilus planipennis, an Asiatic pest of ash trees, is the most destructive invasive forest insect in North America. EAB causes widespread ash mortality, resulting in severe economic losses to U.S. forestry and plant industries, as well as degradation of essential ecosystem services. The proposed work will focus on effectiveness of the current biocontrol programs in protecting North American ash resources through suppressing EAB populations at regional levels by releasing EAB egg and larval parasitoids. The overall goal of this project is to develop strategies that optimize long-term and sustained control of EAB in the aftermath of EAB invasion to protect and conserve ash trees of all sizes in natural and urban ecosystems by releasing introduced natural enemies (Oobius agrili, Tetrastichus planipennisi, and Spathius galinae). Our specific objectives are:
(1) Determine the establishment and/or persistence and impacts of released parasitoids on EAB population densities at new (2018-2021) release sites as well as previous (2008-2017) long-term release sites in Michigan and the Northeast States (Connecticut, Massachusetts, and New York).
(2) Monitor and evaluate ash survival, regeneration, and health (crown) conditions at the new and previous (long-term) biocontrol study sites in both Michigan and Northeast States (Connecticut, Massachusetts, and New York).
Approach:
The proposed work will be carried out in two distinctive regions: (1) infested areas of lower Michigan, where EAB was first detected in 2002 and (2) the Northeast region (Connecticut, Massachusetts, and New York), where EAB was first detected between 2010 and 2013.
In Michigan, six, secondary mixed-hardwood bottomland forests containing both green ash (Fraxinus pennsylvanica Marshall) and white ash (F. americana L.) received releases of O. agrili, T. planipennisi, and S. agrili from 2008 to 2010 (Duan et al. 2013), and S. galinae from 2015 to 2017 after confirmation of successful establishment of O. agrili and T. planipennisi (Duan et al., 2020). More recently, three additional forests (each consisting of paired release and control plots) from this region were also selected as new study sites (~60 km from the six earlier sites) with simultaneous releases of O. agrili, T. planipennisi and S. galinae from 2018 to 2021. Historical data on ash crown condition, EAB densities and associated mortality factors including the introduced biocontrol agents have been collected from the earlier (long-term) biocontrol study sites (along with the paired no-parasitoid release control plots) since 2008. For the newly established biocontrol release sites, however, these data have only recently been collected since 2021 in summer of 2021 and spring 2022.
In the Northeast region (Connecticut/Massachusetts/New York), five long-term sites consisted of secondary mixed-hardwood forests containing green and white ash trees, where O. agrili, T. planipennisi, and S. galinae were released simultaneously from 2015 to 2017 (Duan et al., 2019). More recently, five new forest sites (each consisting of paired release and control forest plots) in Massachusetts and in Connecticut were also established with simultaneous releases of these three biocontrol agents from 2018 – 2020. Historical data on ash crown condition, EAB larval survival and densities, and associated mortality factors including the introduced biocontrol agents have been collected from the earlier established (long-term) biocontrol forests in this region since 2016; however, these data have been only recently collected since 2020.
