Fungal biocontrol for emerald ash borer

Project information

• Research project title: Fungi in Ash Trees: towards protecting trees from emerald ash borer and new diseases
• Taxa: Invertebrate
• Species: Emerald ash borer (Agrilus planipennnis)
• Project status: Complete
• Funding: $500,000

Background

In the past decade, the invasive emerald ash borer (EAB, Agrilus planipennnis) has caused the death of thousands of ash trees across Minnesota.

Larval EAB feed on the layer of ash wood just beneath the bark, leaving behind tunnels (“galleries”) that can stretch up to 20 inches long. This feeding also spreads disease-causing fungi, which can cause tree decay and create hazardous conditions if trunks become too weak to stand. Other fungal species associated with EAB-infestation may be entomopathogenic—that is, capable of parasitizing the insect and killing it or slowing its spread. These fungi would be promising candidates for EAB biocontrol measures.

Prior to this project, managers weren’t sure which fungi—good or bad—have been associated with EAB infestation in Minnesota. This project sought to identify those species for certain and, in doing so, open up new possibilities for managing one of our state’s most devastating tree pests. In local samples, researchers were also on the lookout for signs of another major fungal pathogen: ash dieback.

Research questions

• What fungi occur in trees infested with EAB?
• What fungi contribute to canker formation, wood decay, and tree death following EAB infestation?
• Are any of the fungi associated with EAB capable of infecting and killing the insect?

Practical implications

This research aims to help us understand the complex interactions between EAB and the fungi associated with them. It also seeks to identify fungal diseases linked to EAB infestation and serve as a first step in developing an effective, fungi-based biocontrol option for EAB in Minnesota.
 

Project information

• Research project title: Studies of Entomopathogenic Fungi for Effective Biocontrol of the Emerald Ash Borer - Phase II
• Taxa: Invertebrate
• Species: Emerald ash borer (Agrilus planipennnis)
• Project status: In progress (started January 2023)
• Funding: $342,273

Background

EAB is continuing to spread in Minnesota as its population and impact increases. There is a pressing need to study new methods of control, especially those that may be applied where chemical control is not practical or environmentally safe. Microbial biological control, which uses microorganisms like fungi, may be well-suited for these areas because it is relatively inexpensive. It may also be a self-perpetuating treatment.

During the first phase of this project, researchers found that entomopathogenic fungi (capable of parasitizing insects and killing them or slowing their spread) are present in emerald ash borer galleries. Studies evaluating the fungi for their potential to control EAB have shown some success, but further work needs to be done to determine how best to use fungi as biological control.

Research questions

• What are the entomopathogenic fungi associated with EAB in Minnesota and what is their biology and ecology?
• What procedures promote a pathogenic response? 
• What are the outcomes of using entomopathogenic fungi on to-be laid eggs, larvae, and adult insects?
• What is the best inoculation method for field applications?

Practical implications

If successful, this project will provide new information to validate the use of fungi as biological control to attack the egg, larval, and adult stages of EAB. There would be immediate benefits to managers in Minnesota and regions of North America where EAB is causing urban and forested tree loss. In contrast to chemical treatment, fungal biocontrol may be environmentally sustainable, socially acceptable, and economically viable.