Donald L. Dahlsten
Professor and Entomologist, Associate Dean for Student Affairs
Center for Biological Control 642-7191
217 Wellman Hall
Phone #: (510) 642-3639
FAX #: (510) 642-7428
donaldd@nature.berkeley.edu
Research Interests
The focus of research in our laboratory is on the development of ecologically
sensitive methods for controlling insects that feed on forest trees and
trees in urban environments. The studies are primarily field oriented in
order to gain insight into the ecological mechanisms and trophic interactions
so that the control strategies can be implemented. Most of our work is
with insects that either parasitize or prey on tree feeding insects but
we also work with some species of insectivorous birds.
For almost all of our studies we must first gain some understanding of
the ecology of the host tree and its distribution in the forest or urban
setting. Following this we work on the distribution and abundance of the
insect of interest in order to develop monitoring and sampling methods.
In some situations it is necessary to develop additional sampling methods
for the natural enemies of the target insect. Once we are able to characterize
the system we are working in, we can then attempt to determine the impact
of various natural enemies either naturally occurring or introduced on
the pest insect. We will also be able to determine the impact of the pest
insect on the trees being attacked. We feel that the solution to many of
our forest and urban tree insect problems lies in the understanding of
these biological and ecological mechanisms. The development of pest management
programs that rely on natural processes is our goal and we are particularly
interested in the augmentation, conservation, and importation of natural
enemies.
Current Projects
We have several studies underway involving introduced and native insect
pests of trees and one involving insectivorous birds and their impact on
forest insect defoliators. The first is to develop an integrated pest management
program for the elm leaf beetle. This insect is one of the top three insects
of importance in urban environments in the United States. We have developed
monitoring and timing techniques using degree days but we have been only
partially successful in developing control techniques. We are working in
a city with 4000 elms and are now evaluating the use of a bacterial insecticide
and the introduction of a warm weather adapted egg parasitoid from Spain.
Other strains of these egg parasitoids have been released for several years
with little success.
We are also involved in two other classical biological control programs
that appear to be successful. Both the eugenia psyllid and the blue gum
psyllid were introduced into California from Australia in the past 7 years.
In both cases, a specific parasitic wasp was collected in Australia and
released in California. We are now studying the interaction of the psyllid
pests with their parasitic wasp in order to document the success of these
introductions.
In other studies we are working with native bark beetle species and their
natural enemies. Bark beetles are the most important forest pests in California.
We have been studying the natural enemy complexes of these beetles for
many years and are now trying to identify the mechanisms that bark beetle
parasites and predators use to locate their hosts. To study insectivorous
birds we are using nesting boxes in forest environments. The goal is to
determine the impact that secondary cavity nesting birds have on forest
insect pests. We use video and movie cameras to identify prey items. We
are also studying the reproductive biology of the mountain chickadees,
chestnut-backed chickadees and pygmy nuthatches. The impact of predators,
such as weasels and snakes, on these birds in nesting boxes is being studied
as well.
See the Dahlsten Lab Website for more information.
Selected Publications
Grundel, R. and Dahlsten, D.L. 1991. The feeding ecology of mountain
chickadees (Parus gambeli): Patterns of arthropod prey delivery to nestling
birds. Canad. Jour. Zool. 69:1793-1804.
Dahlsten, D.L., Rowney, D.L., Copper, W.A., and Wenz, J.M. 1992. Comparison
of artificial pupation shelters and other monitoring methods for endemic
populations of Douglas-fir tussock moth, Orygia pseudotsugata (McDunnough)
(Lepidoptera: Lymantriidae). Canad. Entomol. 124(3):359-369.
Dahlsten, D.L., Copper, W.A., Rowney, D.L., and Kleintjes, P.K. 1992. Population
dynamics of the mountain chickadee in northern California. Pp. 502-510.
In: D.R. McCullough and R.H. Barrett, editors, Wildlife 2001: Populations.
Elsevier Science Publishers, Ltd., London, England. 1163 pp.
Dahlsten, D.L., Rowney, D.L. and Tait, S.M. 1994. Development of integrated
pest management programs in urban forests: the elm leaf beetle (Xanthogaleruca
lateola [Muller]) in California. U.S.A. Forest Ecology and Management 65:31-44.
Dahlsten, D.L., Kent, D.M., Rowney, D.L., Copper, W.A., Young, T.E., and
Tassan, R.L. 1995. Parasitoid shows potential for biocontrol of eugenia
psyllid. Calif. Agric. 49(4):36-40.
Current Graduate Students:
Current Post-docs/Researchers/Specialists/SRAs, etc.:
     
|