Hope for the Hemlock in Adelgid fight

Published 1:14 pm Monday, April 13, 2015

The Pacolet Area Conservancy’s (PAC) director of stewardship and land protection, Pam Torlina, recently attended a two-day Community Training Workshop on Hemlock Woolly Adelgid (HWA) (Adelges tsugae).  The workshop was funded by a grant from the Hemlock Restoration Initiative and was offered through a partnership between Blue Ridge Resource Conservation and Development, the N.C. Forest Service, and the N.C. Cooperative Extension Service.  The two-day workshop provided exciting information about the quest to find a way to save the Eastern Hemlock (Tsuga canadensis) and Carolina Hemlock (Tsuga caroliniana) in western N.C. by providing a long term and effective way to manage HWA.

As many know, hemlocks in our area (and up and down the East Coast) have been suffering and dying over the past several years, and many have feared that hemlocks may completely disappear from our landscape, much like that of the American Chestnut (Castanea dentata); however, the tables have turned!  Updated information provided by Dr. Richard C. McDonald, an entomologist with Symbiont Biological Pest Management, suggests a solution that can help save this beloved and ecologically significant tree!

The plight of the hemlocks has been an important issue for Torlina since she was made aware of it in 2003.  In fact, she devoted her Senior Seminar (the capstone course for biology majors) at the University of South Carolina Upstate in 2006 to this topic.  At that time, research stated that (1) HWA, an aphid-like insect, invading hemlock trees was not native to North America, (2) that each HWA adult could lay up to 300 eggs, asexually, twice a year, (3) there were no native predators of HWA in North America, and (4) hemlocks were doomed.

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Since that time, research into predator beetles by government, university, and private entities has continued, with variable results.  However, during the workshop that Torlina attended, presenters offered a spark of hope.  First, it was explained that HWA found in our eastern forests is actually closely related to the HWA native to the Pacific Northwest (PNW) in North America.  Second, HWA in eastern forests lay fewer eggs (dependent on temperature and elevation).  Third, there is a natural predator of HWA from North America, also from the PNW; the Laricobius nigrinus (“Lari”) beetle, and fourth, (the spark turns into fireworks) hemlocks are not doomed!

Dr. Richard C. McDonald, “Dr. McBug,” has been working with “Lari” since its introduction to N.C. in 2006.  At that time, he made an initial, small release in Banner Elk, N.C. Since that time, Dr. McDonald has been able to recover adult beetles from year to year, and after successful establishment larvae and beetles have been found on surrounding hemlocks, and the native “Lari” beetles are spreading rapidly!  As the level of infestation on the hemlocks decreased, trees were able to initiate new needle growth.   More releases were made in the area and the hemlocks all around Banner Elk and beyond are living…and thriving!

HWA is not eradicated from these areas, and it probably never will be, but now there is a predator in place that can help create a natural balance.  The “Lari” beetle and its larvae prey on HWA, decreasing the number of HWA to the point that dieback ceases and the hemlock can produce new growth.

The “Lari” beetle is a winter feeder of HWA, relying on HWA for all stages of development; they feed on HWA from October through May.  During this time, a female “Lari” beetle lays 200-400 eggs.  Each “Lari” larva needs to eat approximately 235 HWA eggs to reach maturity.  Research continues with the discovery of a summer predator of HWA, as well.

As part of this workshop, Torlina received training for monitoring predation of HWA by “Lari” beetles, collecting beetles from areas where they are actively feeding, and also how to release beetles into other HWA infested areas.  PAC will be receiving a “starter kit” of “Lari” beetles to release at a preselected site in Polk County.  This initial group of beetles will be the start of a “Lari beetle farm” armed to prey on HWA in our area.  Over time, PAC will be able to collect “Lari” beetles and release them on other hemlocks in the area to continue preserving our native forest health.

Even with all of this progress in the fight to save our hemlocks, there is much more research that needs to be conducted.  If people are interested in donating in support of further research development in this field, please contact Dr. Richard C. McDonald at drmcbug@skybest.com, and if people are interested in contributing to PAC to secure more “Lari” beetles for release in Polk County, to save our hemlocks, please contact PAC at 828-859-5060 or email info@pacolet.org.  For more information on this topic, please visit the PAC website, www.pacolet.org, and look under the “Conservation” tab.

PAC is a 501(c)(3) non-profit conservation organization (land trust) founded in 1989 to protect and conserve natural resources with emphasis on the lands and waterways with scenic, ecological, and agricultural significance in the North Pacolet and Green River watersheds (PACs mission).  PAC works with area landowners to ensure the long-term protection of their property through voluntary conservation easements (agreements) which enable landowners to maintain ownership of their property, preserving precious natural resources (open lands, forests, wildlife habitat, scenic vistas, farmland, stream banks, etc.), and potentially obtain significant federal, state, and local tax benefits.

PACs vision is a community living and growing in harmony with our natural resources and or goal is to provide a legacy that will endure and be valued by generations to come.  PAC works diligently to provide leadership to encourage conservation and provide education programs emphasizing native species appreciation and responsible land use practices to help – save the places you love.

– Submitted by Pam Torlina