Field evaluation of synthetic aphid sex pheromone in enhancing suppression of aphid abundance by their natural enemies

The effects of lures containing aphid sex pheromone components (4aS,7S,7aR)-nepetalactone and (1R,4aS,7S,7aR)-nepetalactol on abundance of pea aphid, Acyrthosiphon pisum Harris, aphid parasitoids, predators and hyperparasitoids in alfalfa fields were investigated over three years. Although aphid abundance was variable among years, pheromone lure treatment significantly decreased aphid abundance. Among natural enemies of the aphids, only parasitism by the aphid parasitoids Aphidius ervi Haliday and Praon barbatum Mackauer was affected by pheromone lure treatment, with parasitism rates being significantly increased. In contrast, no pheromone lure effects on abundance were detected for predacious species and hyperparasitoids. These results indicate that slow-release formulations of synthetic aphid sex pheromone can attract primary aphid parasitoids and enhance their ability to suppress aphid abundance in the field, and that negative effects on biological control by hyperparasitoids and intraguild predation are not promoted by pheromone lure treatment.