1a. Objectives (from AD-416):
Examine cold-hardiness of potato psyllid under Washington State conditions.
1b. Approach (from AD-416):
a. Determine effects of sub-zero temperatures on potato psyllid, and determine if haplotype affects cold-hardiness. b. Examine survival of infected and uninfected psyllids when exposed to sub-zero temperatures.
3. Progress Report:
The work summarized in this progress report relates to objective number 1 in the Project Plan for 018-00D: 1. Develop new knowledge of behavior, genetics, physiology, and ecology of wireworms, aphids, secondary potato pests, and their natural enemies, that provides opportunities for new and improved biorational control of potato insect pests; and objective number 2 in the Project Plan for 020-00D: 2. Develop bio-intensive methods to manage insect vectors of zebra chip and purple top diseases. Objectives of this project are to determine whether infective potato psyllid is sufficiently cold-hardy to allow it to overwinter under Pacific Northwest winter conditions, and to learn whether all currently known genetic types of the psyllid are equally cold-hardy. Colonies of all 3 genetic types have been established and are under continuous rearing on potato. Protocols for examining cold-hardiness are now being developed for this psyllid species using methods developed earlier for examining cold-hardiness of a psyllid pest of pears. These methods include use of a programmable cold-temperature alcohol bath. Preliminary results indicate that potato psyllid is sufficiently cold-hardy to survive short-duration temperatures of 10 degrees Fahrenheit. Trials are in progress to determine how host plant condition in late August affects survival of psyllids exposed to winter conditions. A final trial in progress is being done to determine whether psyllids infected with the pathogen that causes zebra chip have reduced cold-hardiness. Our ultimate goal at the termination of this project will be new knowledge about whether infective psyllids are able to overwinter under the winter conditions of the potato growing region of Washington State, or whether infection of potato each summer instead requires new colonization of the region by infected psyllids originating in more southerly regions.