Many of us know that bees are at risk, but the specific impacts of our planet’s warming temperatures on bee phenology, or the timing of its life cycle, are only beginning to be understood. As scientists start to compare the changing timelines of pollinator emergence and flight periods with changing plant phenology, they are beginning to see a dissonance that will only continue to grow as Earth gets warmer.
Temperatures are rising earlier each spring, which affects both bees and the plants on which they forage. Bees are emerging early and flying earlier. Plants are emerging and flowering earlier, opening their buds to reveal the nectar and pollen that bees rely on. And of course, this food source also acts as a lure to attract bees to pollinate them. Unfortunately, the timeline of bees are more greatly affected by warming temperatures, causing a mismatch. When pollinators emerge and fly before their host plants are in flower, pollinators can’t gather resources, like nectar and pollen, they need to be successful. Plants miss out on the chance to be pollinated, which many species require for reproductive success. After years of coevolution to fine-tune their relationship, global warming is causing bees and floral associations to miss out on the important services they provided each other. While these missed connections are devastating to plants and pollinators, humans too will soon feel the effect of this dissonance if it continues to grow.
As climate change progresses, the timing between the emergence of bees and flowers will continue to widen which could have severe implications for bees in agricultural systems in that rely on pollination. Three-quarters of crop production relies on pollinators and warming temperatures are only one of many factors that are threatening our bees. Habitat loss, pesticide use, and disease have already reduced and weakened many bee populations around the world. Combinations of these factors may have compounding effects.
The good news is, although some bee species have specific plants that they prefer to forage on, many bees are generalists and can nectar on a variety of plants. Bees are resourceful and will find any nectar and pollen resources that are available. In areas where floral resources are low, planting pollinator friendly plants may help lesson stress on bee populations. Looking towards the future, action to mitigate climate change is the best option to help bees recover. If we are able to slow the rate at which the planet is warming, bees and plants may evolve to emerge, fly, and flower during the same time period once again.