Escape behaviour of the pea aphid Acyrthosiphon pisum (Harris) in response to alarm pheromone and vibration

Pea aphids respond most effectively to the threat of a predator by walking away or dropping from their host plant. Simulating threat by using vibration and alarm pheromone, both separately and together, we found no evidence that escape responses are heritable, nor that individual aphids have characteristic escape behaviours. On the contrary, the amount of alarm pheromone influenced responses: the more pheromone, the more likely an immediate and effective escape. Vibration preceding alarm pheromone greatly increased responsiveness to pheromone, and aphids were more responsive to pheromone after vibration when feeding on stems than when feeding on the undersides of leaves.