D3219: The influence of predation risk on aphid host plant selection

The manipulation of pest behavior has become an important strategy in designing sustainable integrated pest management techniques. Such manipulations can be achieved by augmenting visual, mechanoreceptor or chemical stimulus in the field that represent repulsive or attractive cues related to nutrition, reproduction or survival. Our work explores an alternative stimuli from natural enemies that may trigger anti-predator defensive behaviors in herbivorous insects. These changes in behavior can affect the fitness of the herbivore and reduce damage to host plants, highlighting its potential application in the field. In this research we aim to evaluate how the presence of the predatory ladybeetle, Harmonia axyridis, affects host plant preference and selection in the aphids Myzus persicae. In Y-tube olfactometer assays we evaluated the preference of both aphid morphotypes (winged and wingless) to odors of collard host plants (Brassica oleracea) with or without H. axyridis adults or their isolated chemical cues. In greenhouse choice experiments, we then evaluated host selection of each aphid morphotype when presented with a pair of plants: one that was predator-free and one that had H. axyridis or their cues present. Our findings indicate that both aphid morphotypes can detect predator presence on their hosts via chemical cues which leads to changes in host preference and colonization. Understanding how the presence of predators and their chemical cues influences herbivore host selection behavior will provide valuable information to improve insect management strategies in cropping systems where the ecosystem services provided by predators is essential to plant health.