Social information use across trophic guilds: foraging bumble bees learn from lady beetles

Abstract

Animals use social information gathered by observing other individuals to adjust their behavior to better match the environment and improve fitness. Many insects use social information in various contexts. Bees improve their foraging efficiency by using social information from conspecifics to gauge nectar availability. Bees frequently encounter various heterospecific flower visitors, including those from different trophic groups such as nectaring predators. These heterospecifics may provide valuable information about nectar availability. We determined how bumble bees (Bombus impatiens) use visual social information from lady beetles (Hippodamia convergens). Lady beetles are predators of small insects, but not bees, and also visit flowers to consume floral nectar to increase their reproductive output. Using laboratory-maintained bumble bees freely flying in arenas, we tested if bees could (1) innately recognize lady beetles as sources of social information about nectar, and (2) learn to use lady beetles to gauge nectar availability. Bees did not innately recognize lady beetles as a source of social information. They correctly learned to associate conspecifics with the presence and absence of food, but learned to associate lady beetles only with the presence of food and not the absence. Our results demonstrate social learning across species and trophic guilds, but suggest limits to when and how bees generalize social information from diverse heterospecific flower visitors.