If successful, Smith and Teale
hope that by early this fall they will have a functional prototype system for
identifying ALB-infected trees by the chewing noises coming from them.
Other Control Tactics
Smith is also examining the biology of invasion for this beetle, which
includes studies being conducted under natural field conditions in China in
cooperation with Gao Ruitong and Li Guohong of the Chinese Academy of Forestry
in Beijing, China.
"We hope to find exploitable nicks in the pest's armorpoints in
its life cycle we can take advantage ofto develop eradication or
management tools," he says.
First, he is studying the behavior of adult beetles while they inhabit the
tree, including how male and female beetles find, recognize, and mate with one
another and the steps leading to egg laying, feeding (by adults), and host tree
To date, Smith has uncovered new information never before recorded on ALB
behavior, as well as identified several behaviors that are potentially
exploitable for eradication or management.
Second, by observing the beetles' flight behavior in a single flight, he is
assessing their ability to fly (distance, rate, in-flight orientation, etc.).
"Thus far, preliminary data analysis indicates that the average
distance a beetle flies in a single flight is about 50 yards," Smith says.
"However, since single flight distance may be largely influenced by the
distance between trees within the landscape, this may underestimate the average
single flight distance in urban landscapes where trees are more widely spaced.
Our data show that ALB are capable of single flights of over 437 yards."
Third, Smith is also studying population dispersal behavior under natural
field conditions in China. He wants to show how groups of ALB move over an
entire season (in multiple flights).
"We're uncovering new information on the potential rate of population
spread," says Smith. "It's particularly important that we conduct our
initial studies in areas where the trees are spaced about the same as they are
in the areas infested in the United States."
The immediate use of this information is to help APHIS, which oversees the
ALB eradication program, establish the outer boundaries of its quarantined
areas, as well as predict the direction and rate of spread from infestations in
New York and Chicago.
Results from these studies will also be used by ARS entomologist Jay S.
Bancroft at the Newark laboratory to develop models for predicting ALB
population dispersal within various landscapessuch as parks, woodlots,
plantations, and foreststhat are at risk within the United States,
according to Smith.
"While this is the first year of our multiyear study, preliminary
dispersal results indicate that adult beetles are stronger flyers than
previously thought," says Smith. "Preliminary analysis indicates that
they are capable of dispersing an average of 328 yards over an entire season.
However, the maximum dispersal distance recorded in this study was over 1,530
yards." The study will be repeated in the year 2000.
A recent report listed the ALB flight distance as only 40 to 50 feet.
Referring to this report, Smith says, "based upon our 1999 studies of both
population dispersal and individual flight behavior, ALB is certainly capable
of dispersing or flying well beyond 50 feet." He is apprehensive that
these flight distances underestimate the insects' flight ability or range.
To complement these field studies, lab studies of key aspects of ALB
biology are being carried out with Smith's ARS biological technician Joseph M.
Tropp at Newark.
"These studies will provide new information on the daily reproductive
capacity of adult female beetles over their life span," Smith says. This
is particularly important in light of the beetle's host-tree preference and the
select group of tree species found infested in the United States.
Finally, ARS entomologist Keith R. Hopper at the Newark laboratory, whose
expertise is in the population biology of invasion, is collaborating with Smith
on his studies of ALB colonization behavior and population dispersal.
Using molecular markers, Hopper and Smith are working to determine the
genetic structure of ALB populations in China. By comparing the beetles'
genetics, they plan to show whether beetles tend to stay in the same tree or
move often between trees and to provide additional evidence about how far the
beetles move. This information will be used to determine sampling procedures
for ALB in the United States.
In 1999, Smith, working with Yang Zhong-qi of the Chinese Academy of
Forestry, initiated studies of the known natural enemies of ALB and other
closely related longhorned beetle species in China. They want to evaluate known
natural enemies of ALB in China, as well as find and evaluate new ones, with an
emphasis on parasites of egg and early larval stages.
Smith also plans to search for and evaluate natural enemies of wood borers
indigenous to the United States that may be potential biocontrols of ALB as
Besides this ongoing research, Smith says studies are planned that will
address questions of host-tree preference and suitability for larval growth and
development. These efforts will involve many researchers and organizations,
including APHIS, Penn State University, University of Illinois, State
University of New York-Syracuse, and the Chinese Academy of Forestry, to name a
few.By Hank Becker,
Agricultural Research Service Information Staff.
This research is part of Crop Protection and Quarantine, an ARS National
Program (#304) described on the World Wide Web at
Michael T. Smith is at the USDA-ARS
Beneficial Insects Introduction
Research Laboratory, 501 South Chapel St., Newark, DE 19713-3814; phone
(302) 731-7331, ext. 41, fax (302) 737-6780.