For anyone who recently celebrated World Bee Day, it should come as no surprise that these amazing animals are being studied for yet another mysterious and complex behavior. This new behavior, however, stands out not only for its novelty, but also for its important implications for the future of insect pollinators.
Due to climate change, many plants and animals have shifted their annual timing of reproductive and developmental milestones, such as the production of flowers in plants. Mutualistic relationships, including those between pollinators and plants, are in danger of breaking down unless these shifts can be coordinated across species.
Researchers at ETH Zurich in Switzerland noticed that bumble bees cut holes in the leaves of their host plants, and they wondered if this behavior could be a mechanism for triggering earlier flowering, thus syncing up flower production to the bumble bees’ needs. The researchers performed a series of experiments in which they gave bumble bees access to plants and recorded both the bee behavior and the plant flowering dates. They found that bees most often made the characteristic cuts in the leaves of plants that lacked flowers, and they were more likely to make these cuts if they were hungry rather than well-fed. Furthermore, plants that had their leaves cut by bees started flowering earlier than those that were left undamaged.
These results, which were recently published in Science, imply that bumble bees use this unique leaf-cutting behavior to induce earlier flowering in the plants they pollinate, and thus gain access to critical food resources when they need them. The mechanism underlying the early flowering response in the plants is unknown, but it may be beneficial if it allows plants to maximize pollination through optimal timing of flower production.
While it is unclear how widespread this behavior is, it poses exciting new explanations for how pollinators and flowering plants synchronize their life cycles, which may be critical for their survival in our rapidly changing climate.