E. R. Hinman & Sons

A Burlington CT Lumber Mill

Forestry Insights (Our Blog)

Releasing a “Natural Enemy” to Do What it Does Best!

May 30, 2013 Charlie Leigus


New Haven, CT – The Connecticut Agricultural Experiment Station (CAES) announced that small stingless parasitoid wasps, Tetrastichus planipennisi, will be released Thursday by Dr. Claire Rutledge in the towns of Prospect and Middlebury for the biocontrol of the emerald ash borer (Agrilus planipennis) (EAB). This biocontrol release is conducted in cooperation with Juli Gould of the USDA Animal Health Inspection Service (APHIS) under specific guidelines for the release of EAB parasitoids. The female Tetrastichus wasp lays eggs inside EAB larvae where the developing parasitoid larvae kill the ash borer larvae.

The emerald ash borer is responsible for the death and decline of tens of millions of ash trees from the mid-west to New York State and south to Tennessee. Ash makes up about 4% to 15% of Connecticut’s forests and is a common urban tree.

This destructive insect was first detected in Connecticut in the town of Prospect in July 2012 and was subsequently found in eight other towns, all in New Haven County, as part of surveys conducted by CAES, The Department of Energy and Environmental Protection (DEEP), and the University of Connecticut Cooperative Extension or from reports by the public. The other eight towns are Naugatuck, Bethany, Beacon Falls, Waterbury, Cheshire, Oxford, Middlebury, and Hamden. EAB has also been identified in Dutchess County, New York, Berkshire County, Massachusetts, and Merrimack County, New Hampshire.

“The release of this natural enemy of EAB is another valuable approach in our efforts to manage and slow the spread of the emerald ash borer” said State Entomologist Kirby C. Stafford III.

Another parasitoid, Oobius agrili, which can kill up to 80% of EAB eggs laid in the summer will be released at a later date by Dr. Rutledge. Each female wasp can parasitize up to 62 EAB eggs in her lifetime. So far, these two wasps have been released in 14 of the 19 states where EAB has been found. The wasps, which are extremely specific to EAB, were discovered in China, where EAB originated. They are being reared by the USDA in a laboratory in Brighton, Michigan.

In Connecticut, a quarantine has previously been established that regulates the movement of ash logs, ash materials, ash nursery stock, and hardwood firewood from within New Haven County to any area outside of that county. The quarantine currently applies to only that part of the state and mirrors a federal quarantine also imposed on New Haven County.

In addition to the quarantine, regulations are in effect regulating the movement of firewood from out-of-state into Connecticut or within Connecticut. These regulations were put in place to ensure that EAB and other invasive insects are not carried into Connecticut, or spread throughout New England, through the shipment of firewood.

Detailed information about the quarantine and the firewood regulations can be found at www.ct.gov/deep/eab or www.ct.gov/caes.

The emerald ash borer is a regulated plant pest under federal (7 CFR 301.53) and state (CT Gen. Statute Sec. 22-84-5d, e, and f) regulations. For more information about the EAB, please visit the following website: www.emeraldashborer.info. A fact sheet providing guidelines on the treatment of ash trees to protect them from EAB is also available at www.ct.gov/caes. A factsheet on the biological control of the emerald ash borer is available at http://www.aphis.usda.gov/plant_health/plant_pest_info/emerald_ash_b/downloads/eab-biocontrol.pdf