The purpose of this project was to find a way to make aphid-infested broccoli heads marketable by inducing the aphids to walk away in response to alarm pheromone.

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 proposed to determine which ones cause alarm behavior in this species of aphid and then apply these compounds to infested broccoli heads to determine whether the head can be made marketable.

Specific objectives were to:

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.

The project found no alarm behavior in cabbage aphids raised on crop plants, and the question of whether cabbage aphids raised on wild crucifers produce alarm pheromone remains unanswered.