Blue Gum Psyllid Biological Control Progress Report — September 1992
Date August 28, 1992
Title of Project Blue Gum Psyllid Biological Control
Institution where work is being conducted University of California, Berkeley
Amount of Endowment Grant $ 12, 000
Covering Period 9/91 to 8/92
Anticipated Date of Project Completion/Final Report 3 to 4 years
Individual(s) Conducting Project:
(List Project Leader First)
Donald L. Dahlsten, Project Leader - Title Professor & Entomologist
Telephone Number (510) 642-7191
Richard L. Tassan - Title Staff Research Associate
David L. Rowney - Title Biostatistician
Blue Gum Psyllid Biological Control
Donald L. Dahlsten, Richard L. Tassan, and David L. Rowney
University of California-Berkeley
- A. Project Objectives:
- 1. Study the biology of the blue gum psyllid, Ctenarytaina eucalypti, in California Eucalyptusplantantions.
- 2. Develop a sampling procedure for the blue gum psyllid and its natural enemies.
- 3. Import natural enemies of the blue gum psyllid from Australia.
- 4. Release and evaluate the efficacy of natural enemies of the blue gum psyllid in CaliforniaEucalyptus plantations.
- 5. Develop a biological control program for the blue gum psyllid.
- B. Summary Since Project’s Inception:
- Exploration for blue gum psyllid natural enemies in Australia and New Zealand wascarried out from October 1991 to February 1992. One species of parasitic wasp,
Psyllaephagus pilosus Noyes, was found to attack and kill the psyllid. In addition, several
insect predators were found associated with blue gum psyllid populations.
- A sampling procedure has been developed to monitor psyllid population levels onEucalyptus pulverulenta, a species grown in California for the fresh and processed flower
market and on Eucalyptus globulus, it’s primary host in Australia and a widely planted species
in California. Sampling sites have been established in northern, central and southern California.
This will allow us to study the biology of the psyllid under various California climatic and
cultural conditions and to determine baseline populations prior to the release of imported
natural enemies. This data will be used to assess the post-release impact of the natural
enemies on blue gum psyllid populations in California.
- C. Results to Date:
- The exploration in Austalia and New Zealand resulted in the importation to ourquarantine facilities of Psyllaephagus pilosus, a primary parasitoid of the blue gum psyllid. We
completed the required biological evaluations and requested USDA permission to release this
species from quarantine for propagation in the laboratory and field release. Unfortunately, by
the time we recieved permission to do this the colony had declined below viable levels. We
have since requested Australian and New Zealand collaborators to ship additional material.
We expect to recieve shipments by the end of 1992, and feel that now we will be able to get
USDA approval in a more timely fashion.
- In our California field studies, this growing season we have found that under non-sprayconditions psyllid densities exceed 1000 individuals per terminal shoot on E. pulverulenta and
over 1500 psyllids per shoot on E. globulus. This has resulted in a degradation of plant
growth and shoot appearance. As we observed last year, none of the native natural enemies
appear to have any significant role in reducing psyllid populations.
- D. Future Plans Covered by the Endowment Grant:
- We plan to continue our field studies and refine the procedures to allow growers toefficiently monitor psyllid densities. We expect to recieve additional shipments of the primary
natural enemy, P. pilosus, by end of 1992, with releases into California planned for early
1993.
- E. Anticipated Benefits for Floral Industry:
- Establishment of effective imported natural enemies of the blue gum psyllid will once againallow growers to produce a quality product without the burden of repetative, costly
insecticide treatments.
