Adelgid Genetics  

== 6 of 8 ==
Date: Sat, Mar 1 2008 10:02 am
From: doug bidlack


I just received my most recent copy of Arnoldia. This
is the magazine that the Arnold Arboretum of Boston
publishes. There is an article with the following
title: "The Role of Arboreta in Studying the Evolution
of Host Resistance to the Hemlock Woolly Adelgid".
The authors are Nathan P. Havill and Michael E.
Montgomery. I'll summarize the points that I thought
were most interesting. I'm sure that some or perhaps
all of this info is known to other ENTS, but it was
news to me. Although I've read all previous ENTS
posts, I haven't always read some of the links.

#1) There are five separate lineages of HWA. These
were "inferred using mitochondrial and nuclear DNA
sequence data." Text under a figure showing these
relationships states "Adelgids from China and Taiwan
are different enough that they may be different
species from the one that was introduced to eastern
North America from Japan. There is a second lineage
in Japan that is not the source of the introduction,
and hemlock woolly adelgids in western North America
are a separate lineage that appears to be native, not
introduced as some have assumed." Just to be clear,
the 5 lineages are from China, Taiwan, Japan, Japan,
and western North America. The authors seem to
indicate that each of these lineages are different
enough from each other to be considered as separate

#2) There are 11 separate lineages of Tsuga. These
include the following species and one potentially new
T. mertensiana (Mountain Hemlock)
T. heterophylla (Western Hemlock)
T. canadensis (Eastern Hemlock)
T. caroliniana (Carolina Hemlock)
T. diversifolia (Northern Japanese Hemlock)
T. sp. (Ullung Island Hemlock)
T. dumosa (? - native to Himalayan region)
T. formosana (? - native to Formosa)
T. sieboldii (? - native to southern and low elevation

areas of Japan)
T. chinensis (Chinese Hemlock)
T. forrestii (? - native to a small area in SW China)

The question marks simply mean that I don't know of an
appropriate common name. The potentially new species
is from Ullung Island, Korea.

#3) "Researchers at the National Arboretum have been
able to produce viable hybrid crosses between T.
chinensis and T. caroliniana. These hybrids have been
established in a field trial to evaluate their HWA
resistance and growth characteristics." Carolina
Hemlock appears to be more closely related to the
asian hemlocks than Eastern Hemlock.

My first thought upon reading this paper was; it looks
like researchers have been looking in the wrong place
(China) for natural enemies of our eastern HWA. Maybe
someone needs to be spending much more time in
southern Japan looking for natural enemies of the HWA
that we have here in the eastern US. The obvious
question is why wasn't this work done before spending
so much time and effort on bringing in chinese insects
to control a Japanese pest?


== 7 of 8 ==
Date: Sat, Mar 1 2008 10:33 am


Thanks for sharing this important information. As science bores in, the chances of finding real solutions to the adelgid infestations grows. Unfortunately, a viable solution may not happen soon enough to retain Eastern Hemlock as an important species throughout most of its range. Nonetheless, there is reason for optimism.
I was fascinated by the apparent relation between the Carolina Hemlock and the Asian hemlocks. It looks the part.


TOPIC: Hemlock and HWA paper

== 1 of 4 ==
Date: Sun, Mar 2 2008 3:23 pm
From: David Orwig

just a quick reply to Doug, the genetics of HWA and hence the country
of origin for the HWA in the eastern U.S. was not known until around
2006, the original work with biocontrols from China stem back over a
decade prior, /before/ the country of origin was known. there are many
researchers spending months at a time examining Japanese forests for
other potential biocontrols, including scott Salom's colleages at
Virginia Tech, (Ashley Lamb in particular.) thanks DAVE

David A. Orwig, Ph.D.
Forest Ecologist
Harvard University
324 North Main Street
Petersham, MA 01366
978-724-3302 ext.250

== 2 of 4 ==
Date: Sun, Mar 2 2008 3:32 pm
From: "Edward Frank"


Have they tied any introductions with the Japanese Beetles? Or more importantly has there been any real success as a result of these introductions? Are there any web resources where I can read about them?

(I ask about real success, because in many of the reports I have read, the results read like - "We introduced 200,000 beetles in the fall in a one area, the next spring we found three surviving beetles, therefore this was another resounding success for our beetle release program!!! !)


== 3 of 4 ==
Date: Sun, Mar 2 2008 5:19 pm
From: doug bidlack


it's certainly good to know that there are researchers
trying to find biocontrols for HWA in Japan.

I understand that the genetics of HWA was not known
until 2006, but based on the paper in Arnoldia it
sounds like all the circumstantial evidence was
pointing to Japan rather than China.