1a. Objectives (from AD-416):
Compare biology and vector efficiencies of three genetic types of potato psyllid.
1b. Approach (from AD-416):
• Lab rearing trials to compare development times and survival. • Transmission and acquisition trials using known infected potato, with PCR to determine acquisition of the pathogen. • Laboratory examination of whether infected female psyllids produce infective offspring. • Manipulation of photoperiod to determine effects on diapause response and coldhardiness of genetic types.
3. Progress Report:
The work summarized in this progress report relates to 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. Managing zebra chip in northern potato regions can be more challenging in some respects than managing the pathogen in southern growing regions, due to the uncertainties in northern regions about the geographic source of potato psyllid vectors colonizing potato fields. Specifically, three geographically genetic variants (or haplotypes) of potato psyllid have been identified: western (southwestern U.S., Baja); central (eastern Texas, eastern Mexico); and Northwestern (Washington, Idaho). All three haplotypes have been collected in the Columbia Basin of Washington and Oregon, although with some apparent geographic preferences which are not fully understood. Biological differences among haplotypes, including epidemiology and interactions with the zebra chip pathogen, are largely unexplored. At this time, it is unclear whether growers in the Pacific Northwest should be concerned about all haplotypes or just a subset of haplotypes. The lack of comparative biological studies contributes directly to this question. The objectives of this study are to: 1) compare life history traits among three haplotypes of potato psyllid, 2) determine whether haplotypes are similar in how well they acquire and transmit the zebra chip pathogen, 3) examine transovarial spread (mother to daughter) of the pathogen in all haplotypes, 4) examine end-of-season behavior and physiology (diapause, cold-hardiness) in all haplotypes, and 5) determine whether infection with the zebra chip pathogen affects cold-hardiness. Experiments to address all the five objectives were just initiated. Results from this project will allow us to define whether psyllid haplotypes differ in biological traits that may affect psyllid effectiveness in spreading the zebra chip pathogen under northwest conditions.