An article on the HWA
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lumberjack333
ArboristSite Operative
Interesting article, much better alternative to chemical control imho... just one question - where are the concerns of releasing a beetle native to China into the North American forests? I realize they are experimenting with the different species to see which survives better in different regions/climates, but should there not be concerns as to what else the Chinese beetles will prey on other than the woolly adelgid? Introducing more foreign insects into North America scares me a little...
moss
ArboristSite Guru
An admirable cause and effort but up to this point all beetle releases in the eastern U.S. have failed miserably. There has been zero success in getting any of theses beetles to establish viable populations to-date.
Another problem is that beetles are only part of the adelgid control picture in Asia. The timing of adelgid feeding and the tree's production of the correct terpenoid compounds at the right time is key and you can't "retrain" an eastern hemlock to put out specific kinds of terpenoids at the right times of year. That's a result of many thousands of years of co-evolution between Asian hemlock species and particular adelgid species. We don't have hundreds or thousands of years to prevent extinction of eastern hemlock. The only thing slowing it down is average low temperatures in the northern range of eastern hemlock. The beetles are only one part of the evolved HWA control picture in Asia and based on everything that's been tried up to now they're not up to the task. I wish it were otherwise. That's where the funding is going right now, the thinking is wishful. I hope I'm proved wrong.
-moss
Another problem is that beetles are only part of the adelgid control picture in Asia. The timing of adelgid feeding and the tree's production of the correct terpenoid compounds at the right time is key and you can't "retrain" an eastern hemlock to put out specific kinds of terpenoids at the right times of year. That's a result of many thousands of years of co-evolution between Asian hemlock species and particular adelgid species. We don't have hundreds or thousands of years to prevent extinction of eastern hemlock. The only thing slowing it down is average low temperatures in the northern range of eastern hemlock. The beetles are only one part of the evolved HWA control picture in Asia and based on everything that's been tried up to now they're not up to the task. I wish it were otherwise. That's where the funding is going right now, the thinking is wishful. I hope I'm proved wrong.
-moss
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appalachianarbo
ArboristSite Operative
Exactly. Many different sites, several different beetle species, thousands of beetles (some released by me)....no control.
By the time a sufficient beetle population exists (if ever), our hemlocks will be dead. The best method thus far has been suggested by Dr. Grant (the guy in the article)...
1. Utilize multiple species of beetle with different feeding times to eat adelgid throughout much the year (called bracketing); 2. Build the beetle population in the understory trees and chemically treat larger trees to keep them alive until large beetle populations exist.
Dr. Grant has found that systemic chemical control have had no effect on the predator beetles, which is a good thing for his strategy.
So if our beetles never build a viable population, we may be treating these trees for their entire lives. Our funding efforts need to focus on beetles and other biocontrols, but also need to maintain and expand funding for chemical control.
The argument above mainly relates to large tracts of public lands. As of now, beetles are enormously expensive, and for homeowners, there is no guarantee that the beetles will actually stay on their trees to provide any benefit.
I'll continue to sell chemical control services at the same time hoping the beetles will do their thing soon.
kennertree
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