1a. Objectives (from AD-416):
To optimize sex pheromone attractants for field use in monitoring or managing two species of pear psyllids, pests of pears in North America and Europe.
1b. Approach (from AD-416):
1. Olfactometer trials to demonstrate attractiveness of compounds isolated from female psyllids. 2. Field tests of synthesized forms of products identified in the first objective, using attractant-baited sticky traps. 3. Seasonal comparison in field of the synthesized products, by comparing trap catch of psyllids on attractant-baited traps at various times of season.
3. Progress Report:
The work summarized in this progress report relates to objective number 3 in the Project Plan for 001-00D: 3. Discover and develop chemical attractants for codling moth, fruit flies, pear psylla, and other insect pests of temperate tree fruits and their natural enemies. Objectives of this project are to develop an efficient monitoring tool for pear psylla which incorporates a recently identified sex pheromone attractant, isolated by extraction of the cuticle of female psyllids. Field trials were done to determine how trap color, trap composition, and presence of the pheromone affected trap catch. Traps that had been baited with pheromone partially eliminated the color preferences noted for psyllids colonizing unbaited traps, although this varied seasonally. Trap composition also affected how well the pheromone attracted males. Traps composed of a mesh material, which allowed air to flow unimpeded through the trap and thus disperse the attractant, were more effective than traps composed of a solid material which slowed rate of airflow. The standard delta trap, used in pheromone monitoring of many types of insects, was a very poor monitoring tool, even in the presence of the pheromone. Our results suggested that psyllids were reluctant to enter delta traps even if the pheromone was present. A second objective was to develop a sprayable method for dispensing the pheromone. Field trials suggested that the pheromone can be dispensed in spray applications with an appropriate emulsifier. This result provides opportunities for developing cost-effective means for dispensing the attractant in orchard systems. Assays are being done in cooperation with a scientist in Israel. In all of our assays, the attractant was synthesized by the University of California cooperator.