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Biological Controls

Biological controls are the third part of the three-pronged attack for fighting the Hemlock woolly adelgid, along with cultural and chemical controls.  Biological controls refer to beneficial living organisms that can kill, disable, or otherwise hinder harmful living organisms.  In the case of hemlocks, the biological controls currently receiving the most attention are other insects -- several species of predatory beetles -- that prey specifically and solely on adelgids.  Four research labs in the southeast,* in partnership with the U. S. Forest Service, are rearing these beetles for release on public lands in Georgia with the hope that a predator-prey balance can be established to control adelgid populations to such a degree that the hemlocks can survive and even thrive again. 

See NEWS below!

Challenge

Their valiant efforts face serious challenges, however.  So many beetles are needed, yet supplies are extremely limited.  Rearing beetles is scientifically demanding, labor-intensive, and very expensive, and the beetles that have been released into the wild so far have not kept pace with the prolific reproduction rate of the adelgids.  The picture is further complicated by the fact that, as most experts agree, the biological solution involves developing a complex of predators rather than relying on a single species, a process that requires careful work, much testing, and time.  And as time marches on, hemlocks continue to decline.

Hope

But there is also cause for hope.  The U.S. Forest Service has designated 144 Hemlock Conservation Areas in the Chattahoochee-Oconee National Forest in Georgia for treatment with beetles or chemicals or both (separated by a buffer zone).  About 800,000 beetles have been released in the designated insect areas so far, and researchers have recently documented solid evidence of beetle survival and reproduction in the wild.  The chemicals being used to treat hemlocks in the designated insecticide areas are proving to be quite effective, and while it is recognized that chemicals are a "band aid," they are working very well and buying valuable time in which long-term, natural solutions can be developed.  Click here for a map of the Hemlock Conservation Areas in Georgia, some explanatory information on how the priorities were established, and a chart indicating the location name, treatment method(s), and number of acres for each.

Advice

So what does all this mean for private property owners who want to help their hemlocks?  For now, property owners should continue to treat their trees with a combination of cultural and chemical controls; these are the best solutions from the standpoint of both cost and effectiveness.  Beetles are not yet an advisable option for private property because of the as-yet unproven performance of the single-species approach, the unavailability of the multi-species complex, and the extreme expense.

How to Help on Public Lands

If you would like to help the hemlocks on public lands in Georgia, you can volunteer with any of the Friends of the Parks organizations.  You can also send a donation directly to the labs that rear beetles for release in Georgia listed below.  Make your check payable to the particular beetle lab you want to support and mark it "For Hemlock-HWA Project."

*Research labs rearing beetles for release in Georgia are:
 

Other beetle-rearing research labs in the south include the University of Tennessee, State of North Carolina Agriculture Department, and Virginia Tech.  In the northeast, there are beetle-rearing research labs in New Jersey, Connecticut, and Massachusetts, as well as a small commercial lab in Pennsylvania.

News on the Hemlocks vs. Adelgids Battle

n   Development of Resistant Hybrid Hemlocks -- Efforts are underway by the USDA Forest Service and the U.S. National Arboretum to develop hybrid hemlocks that will be resistant to the HWA.

n   Fifth Hemlock Woolly Adelgid Symposium -- This conference, hosted by the Cradle of Forestry Interpretive Association, will be held August 17-19, 2010 in Asheville, N.C.  Click on the link for more information, including an overview of topics, who should attend, conference registration and hotel reservations, and agenda.

n   Fungi Associated with HWA and Assessment of Entomopathogenic Isolates for Management -- This research paper by W.R. Reid, B.L. Parkerb, S.Y. Gouli, M. Skinner, V.V. Gouli, and H.B. Teillon, describes research on fungal pathogens associated with the hemlock woolly adelgid and their ability to cause mortality in low-density populations of aestivating sistens.

n   Gene Conservation of Carolina and Eastern Hemlocks -- Camcore (Department of Forestry & Environmental Resources at North Carolina State University) and the USDA Forest Service are collaborating to collect seeds from populations of both Carolina and eastern hemlock throughout the southern U.S.  These seeds have been placed in cold storage or have been germinated to establish ex situ conservation plantings in Latin America and the Ozark Mountains of Arkansas.

n   Young Harris College Hemlock Project -- article about The YHC Hemlock Project published on YHC's web site, 2010

n   Beetle Lab Progress Reports -- We are in process of interviewing personnel at the four beetle-rearing labs that provide beetles for release on Georgia's public lands and will publish updates here soon.
 

 Back to HWA Controls       Cultural Controls       Chemical Controls

© Save Georgia's Hemlocks 2009, 2010.  Hemlock Help Line^SM  706-429-8010.
Send comments or questions to donna@savegeorgiashemlocks.org.  Last updated 08/12/2010.