The influence of aphids (Myzus persicae) and pink lady beetle larvae (Coleomegilla maculata) on host plant preference of imported cabbageworm (Pieris rapae)

Abstract Oviposition decisions by herbivorous insects hinge on multiple factors, with some of the most important being enemy-free space and competition for resources. It is important to understand whether and how herbivores and predators can influence the maternal egg-laying preference when they are...
Ausführliche Beschreibung

Abstract Oviposition decisions by herbivorous insects hinge on multiple factors, with some of the most important being enemy-free space and competition for resources. It is important to understand whether and how herbivores and predators can influence the maternal egg-laying preference when they are alone and in combination with host plants. Here, we evaluate whether the presence of aphids (a competitor) or a lady beetle larvae (a predator) influence host plant selection by an ovipositing butterfly. Canola (Brassica napus L.) was the highest quality of three putative Brassicaceae host plants for aphids Myzus persicae (Sulzer) (Hemiptera: Aphididae), while the butterfly Pieris rapae (L.) (Lepidoptera: Pieridae) showed similar survival on all. Canola was used to determine that the presence of a competitor herbivore (aphids) had no effect on butterfly oviposition behavior. However, predators significantly influenced the number of eggs laid on the plants, especially on those plants that had both aphids and a lady beetle larva present in combination. We expect that adult female P. rapae did not lay their eggs on the treatment that involved both herbivorous competition and predation risk, due to the combined risk factors along with the volatile chemicals and aphid alarm pheromones emitted on those plants that contained both the aphids and lady beetle larva. Ausführliche Beschreibung