Dr. Donald L. Dahlsten,

Center for Biological Control, U. C. Berkeley

© The Regents of the University of California, (2004) (last updated 23 Feb. 2005)

Dr. Donald L. Dahlsten passed away on 3 Sept. 2003. Please see the UC Berkeley press release.

A giant sequoia tree was planted in Don's honor by his grandchildren on the Berkeley campus between Wellman Court and Tolman Hall:

Click here to see a picture gallery celebrating Don's last 25 years


The laboratory of Dr. Donald L. Dahlsten operated under the Division of Biological Control (now Center for Biological Control), and the Division of Insect Biology at the University of California, Berkeley from 1963 through 2003.

The focus of research in Don's laboratory was on the development of ecologically sensitive methods for controlling insects that feed on forest trees and trees in urban environments. The studies were 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 this work was with insects that either parasitize or prey on tree feeding insects but we also worked with some species of insectivorous birds and their effects on the forest ecosystem.

CLASSES
PROJECTS:

Red gum lerp psyllid - LERPS

Red Gum Lerp Psyllid Biological Control

 

mountain chickadee 

Insectivorous Birds In the Forest Ecosystem / Wildlife Studies

Ant (winged) 

Argentine Ants and Urban Tree Dwelling Homopterans 

 

Lemon/Spotted Gum Psyllids

 

Blue Gum Psyllid Biological Control 

Economic Analysis of this project

Parasitoids on elm leaf beetle eggs 

Elm Leaf Beetle Integrated Pest Management 

 

Native Bark Beetles, their Natural Enemies, and Fire / Insect Interactions

Eugenia Psyllid Biological Control 

 

Members of the lab in fall, 2003 included:

Dr. Donald L. Dahlsten, Professor 

David L. Rowney, Biostatistician (daver@berkeley.edu)

Dr. Robert Zuparko, Post Doc. Researcher (bz@ nature.berkeley.edu)

Dr. Bruce Jennings, Post Doc. Researcher

Graduate Students:

Kyle Apigian (kapigian@hotmail.com)

Angelica Herrera (gelica@pw.usda.gov)

Deanna Simon (dsimon@nature.berkeley.edu)

Chris Solek (csolek@nature.berkeley.edu)

Other links:

to Dahlsten's Publications

to UCB Biological Control page

to UCB Natural Resources page

to U. C. Berkeley page

Elm Leaf Beetle Integrated Pest Management

The objective of this study was 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 worked in Sacramento, a city with 4000 elms, and evaluated 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. 


Native Bark Beetles, their Natural Enemies, and Fire / Insect Interactions

We studied native bark beetle species and their natural enemies. Bark beetles are the most important forest pests in California. We studied the natural enemy complexes of these beetles for many years and carried experiments to identify the mechanisms that bark beetle parasites and predators use to locate their hosts.

Fire/Bark Beetle Research:  Prescribed fire is seen as the management tool to help remediate the current problems of poor forest health and extensive high-risk fire behavior characteristics.  The potential for prescribed fire to physically alter these characteristics may cause significant tree mortality from the burn itself as well as subsequent mortality to bark beetles in the years to come.  The lab, in cooperation with the U. S. Forest Service, Pacific Southwest Region, measured the extent of beetle-induced mortality from different prescribed fires in the East-side pine ecosystem of Northern California.  Special attention was given to the role of fire in predisposing trees to beetle attack and the effect of fire on tree physiology.  The goal of our work was to provide forest managers in this region with an idea of the severity of tree mortality associated with prescribed fires burned under a wide variety of environmental and fuel conditions.  This addresses the concern for increased use of this management tool and provide findings with direct implications for managing land for reintroducing fire into the ecosystem.

The lab also contributed to the Fire and Fire Surrogate study at U. C. Blodgett Research Forest. We monitored numbers of ground-dwelling arthropods monthly through the summer season on plots with mechanical thinning, prescribed fire, a combination of both, and no treatment.


Insectivorous birds in the forest environment / Effects of management activities and tree diseases on wildlife in forest and riparian environments.

To study insectivorous birds we used nesting boxes in forest environments. The goal is to determine 

the impact that secondary cavity nesting birds have on forest insect pests. We used video and movie cameras to identify prey items. We also studied the reproductive biology of the mountain chickadees, chestnut- backed chickadees and pygmy nuthatches. The impact of predators, such as weasels, bears, squirrels, and snakes on these birds in nesting boxes was studied as well.  We are evaluating ways to limit predation on nests, such as installation of metal bands below the nest boxes on trees.

 Mr. Bear doesn't seem impressed by the band on this tree with an active nest box:

Effects of Sudden Oak Death on wildlife. As part of the Sudden Oak Death Project we monitored bird populations using census points and nest boxes, small mammals using live traps, and reptiles/amphibians using cover boards in plots with and without active SOD infections in norhern California.

Effects of Biological Control of Tamarisk on bird populations. This new study in cooperation with the USDA will monitor birds using census points and nest boxes in riparian plots with and without introduced biological control agents on tamarisk, an invasive exotic invader plant species.

Effects of  Riparian Woodland Management for Control of Pierce's Disease on vertebrates:  In 1997 a study was initiated to study management techniques in riparian woodlands to control Pierce's disease. These techniques involve manipulation of vegetation in riparian corridors between fields of grapevines. Management of riparian woodlands to reduce the incidence of Pierce's disease in neighboring fields must also meet requirements to maintain good habitat for wildlife and fish. We are studying the effect that the experimental treatments have on the vertebrates (birds, mammals, reptiles and amphibians) in these riparian areas. We use a number of procedures to accomplish this: bird and mammal census from fixed spots for fixed time periods; spring survey of nests; observations of animals using artificial nest boxes; predator activity at nest boxes; live trapping of small mammals; photographic surveys using cameras activated by light beam interruption; and monitoring of flat plate shelters for reptiles and amphibians. These procedures are concentrated in the spring-early summer during nesting season, but are continued less intensively through the entire year.

A bobcat photographed by automatic camera unit on a Napa study plot

 


Argentine Ants and Urban Tree Dwelling Homopterans

This study determined relationships between food source stress (primarily tree dwelling Homopterans), environmental conditions, and home invasions by Argentine ants (Linepithema humile). 



(Comments to: DaveR@Berkeley.Edu)