Pollination powers ecosystems and agricultural production, so it’s critical to understand how the process works, what animals are considered pollinators, and why pollinator conservation is important to humans as well as animals, plants, and natural communities. Simply put, pollination occurs when pollen, the fertilizing element of flowering plants, is transferred from the male part of a flower (anther) to the female part (stigma). Ultimately, this transmittal of genetic material activates the production of fruits, seeds, and the next generation of plants. There are two main means of pollination: self-pollination, in which a plant fertilizes itself, and cross-pollination, which entails a vector such as wind, water, or an animal moving pollen from one flower to another of the same species.

Though the non-native western honey bee (Apis mellifera) often serves as the most recognizable pollinator, many animals provide pollination services in Arkansas, including native bees, beetles, flies, wasps, moths, butterflies, and birds. In general, bees are especially renowned for their exemplary pollination abilities, and for good reason: the behavior of many species revolves around this activity, and their bodies are often adapted for efficient pollination. The Department of Entomology at Michigan State University highlights these unique attributes, stating:

“Bees make excellent pollinators because most of their life is spent collecting pollen, a source of protein that they feed to their developing offspring. When a bee lands on a flower, the hairs all over the bee's body attract pollen grains through electrostatic forces. Stiff hairs on their legs enable them to groom the pollen into specialized brushes or pockets on their legs or body and then carry it back to their nest. Individual bees tend to focus on one kind of flower at a time, which means it is more likely that pollen from one flower will be transferred to another flower of the same species by a particular bee.”

While bees are pollination powerhouses, butterflies, by contrast, tend to pollinate flowers inefficiently, although they still conduct some pollination. Unlike bees, butterflies do not have specialized structures for collecting pollen, and their bodies, suspended atop spindly legs, do not collect much pollen.

Of great importance, animal-mediated pollination is responsible for pollinating nearly 90% of the world’s flowering plants. From an agricultural standpoint, insect pollinators in particular provide services resulting in at least 35% of the global food supply; put another way, they are responsible for one out of every three bites of food. In Arkansas, thousands of acres are planted in crops dependent upon or improved by pollination services, and in the U.S. overall, the economic value of pollinators is estimated to be more than $24 billion per year. If you were to think about the pollination services required to make a hamburger, everything except the bun is at least partially dependent on an animal pollinator. Bees pollinated the mustard plant, tomatoes in the ketchup, the cucumbers made into pickles, and even the black pepper, while certain cattle forage like alfalfa, clover, and lespedeza is produced through pollination by several species of bees.

Beyond the food we eat, pollinators support the framework of ecosystems. Illustrating the importance of pollinators to natural communities, the U.S. Forest Service states, “Native pollinators provide most of the pollination in forests and grasslands of the United States, where many wild forb [i.e., wildflower] and tree species require their services.” Many wildlife species depend on pollinator-produced seeds and fruits for food, from the American black bear (Ursus americanus) to songbirds such as the eastern bluebird (Sialia sialis) and wood thrush (Hylocichla mustelina).

Unfortunately, many pollinator populations appear to be experiencing declines, which is alarming given how vital they are to life as we know it. One of the biggest factors affecting pollinators is habitat loss. Additionally, pesticide use, introduced diseases, and climate change are contributing to worrisome declines in populations of bees and other pollinating insects. Thus, reversing downward population trends in pollinators — an enormous task — requires an all-hands-on-deck approach to restore a colossal amount of habitat and implement practices that preserve pollinator health.

References

Photos:
Photo 1 — Brown-belted bumble bee (Bombus griseocollis) shown on the lower left, and two-spotted bumble bee (Bombus bimaculatus) shown on the top of the flower, on green-flower milkweed (Asclepias viridiflora). Photo by Leslie Cooper.

Photo 2 — Eastern tiger swallowtail (Papilio glaucus) on prairie gayfeather (Liatris pycnostachya). Photo by Leslie Cooper.