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Reseachers continue to release parasitoids to fight Emerald Ash Borer

As of February, more than 3 million EAB parasitoids released from Michigan facility.

May 24, 2016

2 Min Read

The Emerald Ash Borer was discovered in Michigan in 2002. The Asian beetle causes widespread ash tree death. Ash trees are prevalent across the United States and federal and state governments spend $29.5 million to manage EAB. Researchers are studying natural enemies of EAB in hopes of suppressing the Emerald Ash Borer so ash trees can survive.

Related: EAB keeps expanding range

-How did EAB arrive in North America and where has it spread?


According to USDA Agricultural Research Service, the Emerald Ash Borer arrived in Michigan in the early 1990s in wood packing materials from China. It is now found throughout Michigan and in areas of Illinois, Indiana, Iowa, Ohio, Pennsylvania, Maryland, Minnesota, Missouri, Virginia, West Virginia, Wisconsin, and Quebec and Ontario, Canada.

Related: Emerald Ash Borer found in another Iowa county

-How does EAB move?

EAB moves long distances through human activities: Moving infected ash firewood, nursery stock, timber or manufactured goods.

-What is biological control?

Biological control is a management strategy for control of invasive pests that involves importing and releasing natural enemies of the pest. USDA Animal, Plant Health Inspection Service grants permits for the release of the “biocontrol agents.”

-Have any “biocontrol agents” been approved for suppression of EAB in the United States?

Four species of parasitoids have been approved: Oobius agrili, spathius agrili, tetrastichus planipennisi and spathius galinae.

1. Oobius agrili kills EAB by injecting its own egg inside EAB eggs where it hatches, grows and kills its host.

2. Spathius agrili lay eggs on EAB larvae, which they feed upon and destroy.


3. Tetrastichus planipennisi lay their eggs inside EAB larvae, killing their host as the larvae grow.

4. Spathius galinae act similarly to spathius agrili.

As of February 2016, a biological control production facility in Brighton, Michigan, has produced and released more than 3 million EAB parasitoids in 22 states and two Canadian providences.

Learn more about Emerald Ash Borer Biological Control Release and Recovery.

Sources: USDA Forest Service, USDA Animal and Plant Health Inspection Service, Agricultural Research Service

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