Biological control is currently the only management option that can be applied at the forest landscape level. The goal of EAB biological control is to use natural enemies to bring EAB populations into balance and reduce damage. There are three species of parasitoid wasps that are approved for release. These species were selected by the US Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) and Forest Service. The parasitoids were tested extensively to ensure that they will not negatively impact other species or the environment. APHIS rears these biological control agents at a specialized facility in Brighton, MI and provides them to states with EAB infestations. More information about biological control in general
Pictured are the adult emerald ash borer beetle, Agrilus planipennis (A) and the parasitoids that control it in China including the egg parasitoid, Oobius agrili (B), and two larval parasitoids, Tetrastichus planipennisi (C) and Spathius agrili (D).
Releasing larval parasitoids
Collecting data and marking trees for long-term monitoring
Two of the parasitoid species attack the larval stage of EAB under the ash tree bark. The other species attack and kill EAB eggs that are in bark crevices. The parasitoids are approximately the size of gnats and do not harm humans or the environment. It is unlikely that humans will encounter these parasitoids at all. This parallels the lack of human interaction with the hundreds of native parasitoid wasp species in Minnesota. More information about the EAB biological control agents
Initiating EAB biological control while EAB populations are low gives the parasitoids an opportunity to establish within the EAB population and move with EAB as it spreads. To be in sync with the EAB lifecycle, the larval parasitoids are released in the spring/early summer and late summer/fall. The egg parasitoids are released mid-summer. Data on ash health, forest tree species composition, and parasitoid establishment are collected for five years post release.
The first release of larval parasitoids occurred on September 22, 2010 at a site along the Mississippi in southeast Minnesota. The Minnesota Department of Agriculture coordinated site selection, data collection, and the release in collaboration with APHIS (provided biological control agents), US Fish and Wildlife Service (USFWS), Army Corps of Engineers (ACOE), and the Minnesota Department of Natural Resources. The site is within the USFWS Upper Mississippi River Refuge. The refuge is co-managed with the ACOE.
All three biological control agent species were released and recovered (detected at least one year after release) in Michigan. We are confident that these species will establish in southern Minnesota which has a similar climate to the areas of biological control agent release and recovery. However, northern Minnesota is colder than Michigan so we are not sure that EAB and its biological control agents will survive northern winters.
Biological control of EAB was developed recently. It will take many years of data collection and analysis before conclusions can be drawn about the efficacy of each of the biological control agent species. Unlike many EAB infested states, Minnesota has the advantage of low EAB populations in isolated pockets. We will use this advantage to implement biological control before EAB populations reach epidemic levels.
Biological control of emerald ash borer (EAB) is new and we need to learn how to implement the most effective EAB biocontrol program as quickly as possible. We are assessing whether the bioagents can survive winter cold in northern Minnesota and learning the bioagent dispersal rate and patterns. With this information, we can calculate which bioagent species to release, when, and where. More information on research
Waging War on a Voracious Pest
Emerald Ash Borer Biological Control Release Guidelines
Biological Control Facility Produces Wasps for Battle Against Emerald Ash Borer (YouTube)
Emerald Ash Borer Control (YouTube)
Biological Control of Emerald Ash Borer Presentation (PDF: 3.67 MB / 26 pages)
Monika Chandler, Biological Control Coordinator
Jonathan Osthus, EAB Biological Control Coordinator
Plant Protection Division
Minnesota Department of Agriculture (MDA), 625 Robert Street N, St. Paul, MN 55155-2538, email@example.com