AGENCY INFORMATION

• Take A Stand
• Hemlock Woolly Adelgid

Take A Stand Update: December 2006

Hello,

I hope this note finds you well and your hemlocks free from adelgid.  I would like to thank you for your participation in the Take A Standvolunteer program; the more eyes we have looking for adelgid the better we’ll be able to detect it and slow-the-spread.  This has been a busy fall for me.  On August 31st, Don Ouellette retired after 38 years of service as a Maine Forest Service Entomologist.  I had a whirlwind tour of Don’s projects during the six weeks our employment overlapped and these days find me still catching up.  In the coming months I hope to host a workshop to introduce new volunteers to our Take A Stand program.  Current volunteers are always welcome to attend these sessions.  Sometime after the training a sweep forhemlock woolly adelgid (HWA) will be scheduled; I encourage all volunteers to try to attend.  It would be an opportunity to go over any questions or suggestions you may have and to reinforce the methods of the survey.  It will also be a great excuse to get outside, be active and get acquainted.  A notice will go out when more details are ready.    In the meantime, please don’t hesitate to call or write with questions, comments or observations—my contact information is at the end of this update. 

Survey Update

This year we received volunteer survey reports from South Berwick, Eliot, and Saco.  A special thank you goes to all the volunteers who sent in reports.  The good news is, on the over 200 acres surveyed, all reports were negative.  When you survey a stand, please send in a report, even if you have all zeroes or if you are not able to survey all the hemlocks needed to reach the threshold.  You can mail your reports any time to:  Allison Kanoti, Entomology Lab, 50 Hospital Street, Augusta, ME  04330 or fax them to (207) 287-2432.  Wayne Searles, our field technician whom most of you have met, is in the midst of conducting the regulatory survey for York County.  He is about half way done and has not found HWA in any new towns. 

Hemlock Woolly Adelgid Update
Hemlock woolly adelgid in Maine overwintered well last year, and they have had several generations without significant mortality.  This has led to a buildup of their populations where they are established as well as new spot infestations.  To date, HWA has been found scattered on about 6,500 acres of native forests in Kittery, York, Wells, Eliot and South Berwick.  We continue to use an integrated slow-the-spread management approach.  One management tool we use is reduction of populations using chemical controls in areas where artificial spread (by people) is likely.  In November, approximately 17 acres in Kittery, York and South Berwick were treated in this manner. 

 

 

Predator Release
A second tool in our slow-the-spread management plan is biological control.  Predatory lady beetles (Sasajiscymnus tsugae) were released in 2004 and 2005 in Kittery to help reduce HWA populations.  Adults and larvae have been recovered in the vicinity of previous releases, but they have not reached numbers where they can control the adelgid before hemlocks are seriously injured.  In order to reach these populations we need time and more beetles. 

A newer player on the biological control front is a tooth-necked fungus beetle native to the Pacific Northwest (Laricobius nigrinus).  We received a shipment of these predators, and on Halloween released 300 in a Kittery hemlock stand (Figure 1).  In their native range, Laricobius feed on HWA.  Although they will feed on other adelgids, they can only complete their life cycle on HWA.  They are most active in the colder months of the year (when HWA are also active).  The beetle’s native range tends to have a milder winter climate, so it will be interesting to see how well they survive our winters.  Wayne and I set up temperature recorders to see what temperatures the Laricobius beetles and their prey will be exposed to over the winter.  We will survey for adults next fall at the release site, and will report the results this time next year. 

 

 

New Research
This fall Nathan Havill, a Yale University Post-Doctoral Associate, presented findings from his doctoral studies in a seminar at the University of Maine.  Nathan’s research into HWA genetics revealed that there are a number of HWA strains in Asia including at least two in Japan (high and low elevation), one in Taiwan, and several in mainland China (Figure 2).  He found that HWA in the eastern United States is most closely related to HWA in lowland, southern Japan.    What does this mean for us?  The adelgid found in our area is adapted to mild climates; this finding helps to explain the limited cold tolerance of HWA in the northeast.  Additionally, these results indicate that we need to try to prevent other strains of HWA from reaching our forests.  Strains from other locales may cause more or less damage to our native hemlocks than the one currently here.  They may also vary in their degree of cold tolerance.  Interestingly, Nathan’s work revealed that the HWA in western North America is a different strain than any of the others he collected.  There is also a high degree of variation in the genetic makeup of the western North American population.  These findings, as well as western hemlock’s tolerance of HWA and the presence of native predators of HWA in the West, provide evidence that HWA may be native to the area.  On a local note, Maine Forest Service Entomologist Charlene Donahue contributed some of the adelgids used in Nathan’s study.  Details from this portion of Nathan’s doctoral research are published in:

Havill, N.P., M.E. Montgomery, G. Yu, S. Shiyake, A. Caccone.  2006.  Mitochondrial DNA from Hemlock Woolly Adelgid (Hemiptera: Adelgidae) Suggests Cryptic Speciation and Pinpoints the Source of the Introduction to Eastern North America.  Annals of the Entomological Society of America 99: 195-203.

A link to this article is available on his website http://pantheon.yale.edu/~nph3/.

Thanks again for volunteering your time to help detect hemlock woolly adelgid and for taking a stand for our valuable hemlock resource.  Your eyes and efforts are greatly appreciated.  Please do not hesitate to contact me. 

Allison Kanoti
Forest Entomologist

Maine Forest Service Entomology Lab
50 Hospital Street
Augusta, ME  04330
Phone: (207) 287-3147
Fax: (207) 287-2432
E-mail: allison.m.kanoti@maine.gov

 

 

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