Learning may help pollinators find their host plants in polluted landscapes

Abstract

Pollination strongly contributes to food production, and often relies on pollinating insects. However, atmospheric pollution may interfere with pollination by disrupting floral plumes that pollinators use to navigate to flowers.\n\nIn this study, we examine the impacts of pollution-induced elevated ozone levels on the composition of a floral blend of Nicotiana alata and examine the response of innate and trained Manduca sexta to the ozone-altered blend.\n\nOzone exposure altered the floral blend of N. alata, and disrupted the innate attraction of naive M. sexta to the altered blend. However, associative learning can offset this disruption in attraction. Moths that were enticed with visual cues to an artificial flower emitting an ozonated blend learned to associate this blend with a nectar reward after just one rewarded experience. More importantly, moths that were rewarded while experiencing the unozonated floral blend of their host subsequently found the ozonated floral blend of the same host attractive, most likely due to experience-based reinforcement of ozone-insensitive cues in the blend.\n\nThe attraction of moths to both unaltered and ozonated plumes is critical for tolerating polluted landscapes. At the host plant, where moths feed, floral emissions are relatively pure. As floral odors travel away from the host, however, they become degraded by pollution. Therefore, targeting the flower requires recognizing both conditions of the odor. The ability to generalize between the pure and ozone-altered scents may enable pollinators like M. sexta to maintain communication with their flowers and reduce the impact anthropogenic oxidants may have on plant-pollinator systems.