Susceptibility of the Pea Aphid (Homoptera: Aphididae) to an Insecticide and a Predator in the Presence of Synthetic Aphid Alarm Pheromone

Abstract

The potential to manipulate pea aphid, Acyrthosiphon pisum (Harris), populations with synthetic alarm pheromone interacting with chemical or biological control was tested in greenhouse studies. Because alarm pheromone stimulates aphid movement, synthetic alarm pheromone may have the potential to act as a behavioral synergist for insecticides applied on plant surfaces. (E)-²-farnesene had a synergistic effect when combined with malathion; pea aphid survival decreased by 14.7%. An alternative application for alarm pheromone is disruption of effective alarm communication between aphids in the presence of a high background level of synthetic alarm pheromone. Under these conditions, predators may become more effective in feeding on aphids. This hypothesis was not supported by our experimental results with the predator Nabis americoferos Carayon. There was no significant effect of alarm pheromone on the effectiveness of this predator. However, we did not maintain the close proximity of individuals found in aphid colonies, where lack of response to alarm signals might be more deleterious. An additional experiment addressed the question of whether habituation or sensory adaptation could playa role in these potential applications for alarm pheromone. Aphids no longer moved in response to the presence of alarm pheromone 30 min after it was introduced. The potential role of habituation or sensory adaptation must be considered in designing applications for alarm pheromones.