Threatened Forests: Woolly Adelgids Attacking Hemlocks
A silent killer is blazing a
trail through the Appalachians, leaving countless dead hemlocks in its wake. The
assassin is a tiny invasive insect from Japan, the hemlock woolly adelgid
(HWA).
It is stealthy and brutal,
causing 80-90 percent mortality of eastern and Carolina hemlocks. Many fear the
loss of these ecologically significant and charismatic forest species
altogether.
Just as destructive is HWAs evil stepsister
from Central Europe, the balsam woolly adelgid (BWA). BWA causes significant damage to true fir
forests in the eastern and pacific northwestern areas of the United States.
In the southeastern United States, BWA
specifically infest Fraser firs, North America’s most popular Christmas tree, and in the past four decades, BWA has spread to every fir stand in the
southern Appalachians. The effects of BWA coupled with increasing air pollution has resulted in the
death of over 95 percent of mature Fraser fir trees.
However, one group endeavors
to restore hemlocks and other native trees in the
Eastern United States that have succumbed to the adelgids. The Alliance for Saving Threatened Forests
(ASTF), a working coalition between multiple universities and agencies, aims to
develop trees resistant to adelgids and offers a future for hemlocks in natural
settings and the nursery/landscape industry.
ASTF is a regional nonprofit specifically interested in breeding trees
for resistance against invasive insects, and understanding the biological basis
for resistance. Modeled after
the American Chestnut Foundation, ASTF was created in 2007 by a group of scientists representing various universities,
the National Arboretum, the USDA Forest Service, and is led by scientists at
NCSU.
The ASTF collaborates with
experts across the country to try and understand differences in species susceptibility
and determine if a selection or breeding program can produce resistant trees.
Current plans for ASTF include employing a breeding and selection approach to develop resistant planting stock and
accelerate natural selection in restoring hemlock.
You can help us reverse the
impact of adelgids on our native ecosystems. Visit us at www.threatenedforests.org or on Facebook and donate today, and tell
someone else about this effort or to learn more about
ASTF and current research.
Erin C. Mester
is working toward her master's degree in entomology at North Carolina State
University with Dr. Fred Hain on rearing the balsam woolly adelgid. She is
currently the development officer with ASTF. Contact her at ecmester@ncsu.edu.
Photo of healthy hemlock credit Ben Smith.
