Tuesday, August 14, 2012

More on the Emerald Ash Borer

When the Emerald Ash Borer (Agrilus planipennis) was detected in Prospect on July 16,  2012, Connecticut joined the ranks of 15 other states where infestations of the Emerald Ash Borer (EAB) have been found. [Details on its life cycle and the press conference which announced its discovery can be found in my initial blog post of July, 21.] The EAB feeds exclusively on ash trees and is responsible for the death and decline of tens of millions of ash trees, of all species, from the Mid-West to New York state and south to Tennessee. Infestation of an ash by EAB usually leads to the tree's death, often within two to three years.

How was the EAB discovered?
Purple detection traps, known as “Barney traps” because of their color, baited with manuka oil (a chemical lure to attract any EABs in the area), have been used in Connecticut since 2008. They are hung in ash trees in May, checked three times, and then removed in September. Initially, a total of twenty traps were deployed. In 2011, in anticipation of the EAB's arrival from New York, 940 traps went up. In 2012, 540 traps were hung in more carefully targeted areas. Traps, however, were not the means by which the EAB’s presence in Connecticut was first detected.

Dr. Claire Rutledge hanging a purple trap.
Photo by Mioara Scott.

The EAB is a prey of Cerceris fumipennis, nicknamed the “Smoky-Winged Beetle Bandit,” a ground-nesting, non-stinging native wasp, which hunts beetles in the family Buprestidae, which includes EAB. Scientists along the eastern seaboard and in parts of the Midwest have been using Cerceris as a bio-surveillance tool. They have recruited an army of citizen scientists as “wasp watchers,” who monitor baseball fields adjacent to woodlands during the peak of Cerceris hunting time — late morning to early afternoon on hot, sunny summer days. Their assignment? To intercept the Cerceris prey before she (always a female) can get her catch into her underground burrow. If the EAB is in the area, it is evident in the Cerceris catch. Dr. Claire Rutledge, a scientist at the Connecticut Agricultural Experiment Station (CAES) in New Haven, has been assembling a cadre of Cerceris watchers in the state for the past several years. This past summer, the watchers included 17 Master Gardeners who signed on after wasp watching was approved as an official outreach activity.

Mioara Scott, who has worked with Dr. Rutledge for five summers, was the one who found Connecticut’s first confirmed EAB — in Canfield Park in Prospect, in northern New Haven County. She caught the Cerceris wasp carrying the female EAB that then was sent to USDA Animal and Plant Inspection Service (USDA APHIS-PPQ) offices for verification. After the initial discovery, watchers captured 25 more EABs at Canfield, and three more at nearby Fusco Field. An EAB was caught in Beacon Falls later that week. EAB was also discovered in a catch sample submitted by the wasp watcher (a Master Gardener) assigned to Canfield Park. This triggered an early check of purple traps in the area. A trap in Prospect yielded three, and EABs were found in traps in Naugatuck State Forest and in Bethany. Summer surveillance in Fairfield, Litchfield, and Middlesex counties has not yielded any EABs; the newly confirmed infestation seems to be confined to the Prospect area. 

The Prospect, CT EAB
(Actual size approximately 1/2" long)
Photo by Katherine Dugas

Why Is everyone so concerned? 
Ash makes up 4% to 15% of Connecticut’s forest and is a common urban tree. An important source of food for a wide range of native wildlife, ash is already in decline because of a disease called ash yellowsThere is concern that the EAB could reduce the population of ash in the state to a point where it might not be able to recover, potentially causing a ripple effect in the ecosystem of Connecticut’s forests.

How did the EAB travel to Prospect? 
Prospect is a good distance from Dutchess County, New York, along the Hudson, where EAB was detected earlier this year. Some speculate that the EAB may have blown into Prospect on storm winds, but more likely the EAB arrived on firewood. The EAB has great flight potential. Movement of firewood containing EAB to a new location gives the beetle the opportunity for rapid expansion of its territory —the quickest way to spread the infestation. 

What are the current action steps and goals?
  • Establishing the borders of the current infestation. Now that wasp-watching season has ended, and the EAB’s adult life cycle stage is about over, means of detection will shift to physical examination of trees in the Naugatuck State Forest for signs of EAB presence. 
  • Slowing the infestation’s spread. On August 9, the Connecticut Agricultural Experiment Station issued the terms of a quarantine on the movement of hardwood and hardwood products out of New Haven County, to take effect immediately. You can read the full text of the quarantine here.

What can you do to stop the EAB?
  • Inform everyone you know.
  • Don’t Move Firewood.
  • Be alert. Watch for visible signs of infestation. If you see something, immediately call CAES (203-974-8474) or email: CAES.StateEntomologist@ct.gov
  • Become a wasp watcher. Volunteers normally watch once a week for an hour or two at a time during the six to eight week Cerceris hunting season, from late June until early August. Visit cerceris.info for more information, and then email Dr. Claire Rutledge (Claire.Rutledge@ct.govif you are interested in joining the program. You will need to commit to a one-hour training session and approximately ten hours of active wasp watching.

Thanks to Cerceris and the wasp watchers, we know EAB has arrived in the state. Connecticut now has an action plan. People are mobilized. Let’s hope it’s in time to save Connecticut’s ash trees.

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