Harnessing aphid alarm pheromone to rid broccoli heads of aphids

Investigator: Phillip Fujiyoshi, Dept. of Plant Pathology, University of California, Davis
Project location: Davis, California

Summary
Organic broccoli can be made unmarketable when aphids infest the head. Aphid alarm pheromone is a compound or mixture of compounds that causes an aphid to leave its feeding site. Using compounds known to be released from cabbage aphids when they are crushed, we will determine which ones cause alarm behavior in this species of aphid. We will then apply these compounds to infested broccoli heads to determine whether the head can be made marketable, and if so, to come up with an efficient method for cleaning infested heads post-harvest.

Furthermore, we will examine the feasibility of producing the necessary compounds on-farm using plants that can be grown by a farmer. If aphid-infested broccoli can be made marketable, organic growers will have the opportunity to profit under circumstances that currently cause economic loss.

Specific objectives are:

1. Establish the existence of aphid alarm pheromone;
2. Determine the compounds involved in cabbage aphid alarm response;
3. Remove the aphids from infested broccoli heads using alarm pheromone;
4. Develop plant-based alarm pheromone from plants that can be grown on-farm;
5. Document labor and material costs of aphid removal.

Successful achievement of these objectives will reduce organic farmers’ vulnerability to the variation in insect population dynamics and increase their income, making the choice to farm organically more promising.

A final report describing the results of this project is expected in February 2010.