Each & Every Bee Matters

August 1, 2013

Here at Bee America we naturally think mostly about the honey bee. However, we have such a bountiful profusion of flowers in our apiary at this time of year that our attention is drawn to the other pollinators that often visit, particularly butterflies and bumble bees. I’m often charmed by the sight of a bumble bee gently and slowly ambling from one pollen-laden flower to another. A distant cousin to honeybees, its body shape is more rounded than elliptical. In addition to being less streamlined in appearance and in flight, bumble bees are fuzzy, which probably explains why they’re a staple in children’s picture books.

Unfortunately, some species of bumble bees are disappearing at an alarming rate. A large survey of bumble bees in the United States demonstrated that several species have declined substantially over the past two to three decades (Patterns of widespread decline in North American bumble bees. Proceedings of the National Academy of Sciences, 2010). Researchers believe that a combination of factors are likely responsible for reductions in bumble bee numbers, including parasites, pesticides and habitat fragmentation, although a fungus originating in Europe may be the primary cause.

Given the bumble bee’s fragile status, I was especially struck by the findings from a new study about the effects of bumble bee pollination on the ecosystem. While previous research on a variety of different animal species has shown that competition often results in a species developing specific traits and/or behavior over time, this new bumblebee study is one of the first ones to link this evolutionary mechanism to the functioning of an ecosystem (Single pollinator species losses reduce floral fidelity and plant reproductive function. Proceedings of the National Academy of Sciences, 2013). Scientists know that when there are a lot of pollinators around, competition ensures that each bee, butterfly and other insect develops specific affinities for particular plants during an area’s growing season.

Computer simulations suggest that if a pollinator species disappears from an ecosystem, there would be enough redundancy to ensure an ecosystem’s continued health. The study authors wanted to test this theory using bumble bees and did so by removing a particular species and observing the effects on the plant communities. While the remaining bees, as expected, began to visit the flowers previously pollinated by the missing bees in addition to those flowers they originally specialized in, the results were anything but reassuring. As plants need pollen from the exact same species of plant to thrive, pollinators that visit many different species can actually transfer the wrong kind of pollen, which is very bad from a plant’s perspective.

What I take away from this study is that biodiversity is vitally important. Our planet needs multiple species in an ecosystem to promote its—and ultimately our own—optimal well-being. People typically believe that redundancy makes for robust and adaptable environments (i.e., if multiple species perform similar functions then loosing one would not be that big of a deal). However, this study suggests that nature’s back-up plan may have unintended consequences: the very competition that originally creates a healthy and balanced ecosystem can actually harm it should one of the species in this delicate equilibrium disappear.