By Ellen Rigell, Educator at Butterfly Pavilion

If you’ve ever enjoyed a rich tomato sauce on a pizza, appreciated a glorious field of wildflowers, or indulged in a delectable mouthful of chocolate, you’ve benefited from pollinators! These animals provide a key ecosystem service by facilitating plant reproduction and, in turn, supporting food production around the world. To further understand the importance of pollinators, we’ll uncover what a pollinator is, how it impacts our ecosystems and communities and take a closer look at the pollinators in our own backyard.

A pollinator is an animal that transfers pollen between the anther of one flower to the stigma of another, helping the plant produce seeds. These animals (including species of bees, butterflies, moths, beetles, ants, bats, birds, and even some small mammals) visit the flowers to feed on the nectar or pollen, and consequently fertilize the plant.

Pollination benefits both the plant and the animal, making these relationships a great example of mutualistic symbiosis - a relationship in which each species has a net benefit. Pollination happens when a pollinating animal visits a flower to seek out the food rewards: protein-rich pollen and carbohydrate-rich nectar [2]. In the process, the pollinator collects some of the pollen grains on its body (e.g. the bee’s pollen basket and the hummingbird’s bill), which then rubs off on the stigma of the other flowers it visits. After this transfer, the flower is fertilized and can develop the fruit that will protect and disseminate the seeds. The process of pollination is key to both sustaining the food source for the pollinators while also facilitating the reproduction of the majority of the world’s flowering plants. Plants and pollinators need each other to survive!

In fact, the relationships between plants and their pollinators present some of the most stunning examples of coevolution on earth. While some pollinators are generalists and can visit a multitude of different flowers, many pollinators have developed a preference for types of flowers, and vice versa. To start, most pollinators have their favorite color of flower: bees are most attracted to blue, butterflies to pink and red, flies to yellow and white, beetles and bats to white, and hummingbirds to red. Additionally, the flower’s phenology, shape, and food reward offering can all influence what kinds of pollinators visit [3]. For example, bees can see ultraviolet light and are more adept at perceiving bilateral symmetry. Therefore flowers that hope to attract bees will likely take advantage of these visual cues to draw the bee toward the flower’s center [2].

Compare the same flower under natural and ultraviolet light to glimpse how bees see the world.

Plants and their affiliated pollinators have influenced each others’ development dramatically, often resulting in specialization that can even trend toward an exclusive relationship. A favorite example of this is Madagascar’s Star Orchid (Angraecum sesquipedale) which has a foot-long nectar tube that can only be pollinated by a species of hawk moth (Xanthopan morganii praedicta) with its 8-14 inch long proboscis. The exquisite Star Orchid-Hawk Moth relationship even helped Darwin support his theory of evolution [4]!

Hawk moth pollinating the Star Orchid

Why are pollinators important?

There are approximately 200,000 animal species that act as pollinators worldwide, and 99.5% of these are invertebrates (animals without spines). Animal pollinators are responsible for the pollination of an estimated 87.5% of the world’s flowering plants [1]. All across the globe, these tiny critters provide one of the most critical ecosystem services, keeping both our culinary experiences and the world’s habitats thriving.

The status of pollinator populations has huge implications for agriculture. While some crops, like wheat and corn, are wind pollinated and some others reproduce vegetatively like potatoes, a whopping 35% of crop production relies on animal pollinators [6]. That means we have pollinators to thank for one in every three bites of food we eat! Because so many of the world’s fruits, vegetables, nuts, and seeds rely on pollinators, that 35% encompasses a huge diversity of flavors and nutrients [5,6]. To further put this into perspective, pollinators add upwards of $200 billion to the world’s economy [7,8]. The immensity of this service is being realized in Brazil where increased insecticide use and the subsequent decline of carpenter bees has necessitated the expensive and time-consuming process of pollinating passion fruit plants by hand [5].

Beyond our gardens, kitchens, and dinner tables, the impact of animal pollinators can easily be extrapolated to global biomes. With so many of the world’s plants relying on pollinators for reproduction, these flower-loving friends are inadvertently supporting soil stabilization, animal habitats, and carbon sequestration. Supporting healthy pollinator populations translates to supporting healthy ecosystems.

Colorado Pollinators

With about 950 bee species, Colorado has the fifth highest bee diversity in the county, not to mention the hundreds of species of butterflies, moths, beetles, wasps, flies and hummingbirds that also grace our flowers [9,10]. Native species are often more effective pollinators and outperform the non-native honeybee when pollinating native plants like blueberries, tomatoes, squash, and apples [11].

Most of our friendly neighborhood pollinators are solitary bees. Often ranging from black to metallic blue in color, these bees don’t match the image most people picture when they think “bee” [12]. Unlike honeybees and bumblebees which live in colonies with delegated roles, solitary bees lead more independent lives with the female building and provisioning her own nest. Depending on the species, these nests might be burrows in the ground or tucked inside a small beetle-excavated cavity on a log [13].

Colorado Solitary Bees L-R: Digger Bee (Anthophorini sp.), Mason Bee (Hoplitis fulgida), and Cuckoo Bee (Coelioxys sp.)

Another charming example of Colorado’s native pollinators is the Pawnee Montane Skipper (Hesperia leonardus montana). This member of the Hesperia leonardus species group is endemic to the South Platte River Valley, meaning that the 38 square miles in the Colorado mountains is the only place in the world to find this tiny butterfly. Because the Pawnee Montane Skipper occupies such a limited range, it is very vulnerable to changes in its environment. Habitat loss, catastrophic wildfire, and climate change all pose risks that have resulted in the Pawnee Mountain Skipper being federally listed as a threatened species [14].

Pawnee Mountain Skipper on the flowers of Prairie Gayfeather

Coming in all shapes and sizes, pollinators around the world provide a crucial service to our communities and environments. These species have developed incredible adaptations, often evolving alongside their plant communities to form the dialed mutualistic relationships we see today. The act of transferring a few pollen grains between flowers may seem small, but the impact these creatures have on global food production and ecosystem health is undeniably large.

With an incredible diversity of pollinators right in our Colorado backyards, it’s easy to appreciate the value they bring to our beloved gardens and open spaces. While Insecticides, habitat loss, and climate change have caused pollinator populations to decline, increasing nesting habitat and food availability are powerful actions that can boost pollinator densities [6]. Whether you want to go all in on an apiary (collection of beehives), create solitary bee house or plant a native pollinator garden, supporting pollinators can be easy and rewarding [15,16]!

Sources

1. https://onlinelibrary.wiley.com/doi/full/10.1111/j.1600-0706.2010.18644.x
2. https://www.storey.com/article/how-flowers-bees-evolved/
3. https://academic.oup.com/aob/article/118/2/249/1741474
4. https://www.researchgate.net/publication/270876418_The_Pollinators_of_the_Malagasy_Star_Orchids_Angraecum_sesquipedale_A_sororium_and_A_compactum_and_the_Evolution_of_Extremely_Long_Spurs_by_Pollinator_Shift
5. www.sciencedaily.com/releases/2006/10/061025165904.htm
6. http://doi.org/10.1098/rspb.2006.3721
7. https://academic.oup.com/bioscience/article/56/4/311/229003
8. https://www.sciencedirect.com/science/article/abs/pii/S0921800908002942
9. https://beesneeds.colorado.edu/introtonativebees.html
10. https://www.colorado.gov/pacific/agplants/native-pollinators
11. https://www.biologicaldiversity.org/campaigns/native_pollinators/pdfs/NativePollinatorFactsheet11-17-2014.pdf
12. https://planttalk.colostate.edu/topics/insects-diseases/1480-solitary-bees/
13. https://beesneeds.colorado.edu/introtonativebees.html
14. https://www.arcgis.com/apps/MapJournal/index.html?appid=579f9f334de143cf8faf5262f3901a06
15. https://pollinators.msu.edu/publications/building-and-managing-bee-hotels-for-wild-bees/
16. https://extension.colostate.edu/topic-areas/insects/creating-pollinator-habitat-5-616/