Making Room For Native Pollinators

By: Seneca Kristjonsdottir

CU Museum of Natural History, Entomology Collections

CU Museum of Natural History, Entomology Collections

North America is home to thousands of native pollinators. They range from the small metallic green sweat bees and large fuzzy bumble bees, to zipping humming birds, beetles, desert bats, and even some sloth species. The foundational role of these keystone species is often unnoticed, but their pollination services are essential to the success of ecosystems and many of our own agricultural crops. Pollinators and their flowering partners have supported ecosystems all over the world due to an abundance of varying relationships between them. Unfortunately, the resilience within abundant relationships has been dismissed by American agricultural practices. We have come to rely on a single pollinator, the honeybee, for the success of many crops in order to meet the country’s nutritional demand. In recent years, a sharp decline in commercial honeybee populations has caused many specialists to reexamine our mono-cultured practices. Wild pollinators have the potential to inspire more resilient agricultural systems, but inviting wild pollinators back into our agricultural landscapes will require both a structural and paradigmatic shift within agricultural practice.

Pollinators and flowering plants have evolved alongside one another, perfecting the dance of pollination, for centuries. As pollinators forage from flower to flower to reap the reward of nectar and pollen, they also unintentionally fertilize the flowers they visit through the spread of pollen grains from one flower’s male parts to a corresponding flower’s female parts. A properly fertilized flower is able to fruit and produce seeds. Proper pollination is required for 80% of plants to reproduce, including fruits and vegetables in our diet that contain vital nutrients, vitamins and minerals (Pollination). We depend on pollination for at least one-third of our diet. Due to these demands, the economic value of this ecological service in North America is valued at $20 billion per year (Eilers, Spivak 34).

While some plants are pollinated by mammal and bird species, the majority depend largely on bees. While there are thousands of bee species in North America alone, American agriculture has relied on the pollination services of the domesticated honeybee alone since the industrial revolution. Today, commercial beekeepers work hard to keep up with the pollination demands of large-scale mono-crops. On the backs of semi-trucks, migratory beekeepers haul thousands of beehives around the country to pollinate almonds, oranges, blueberries, alfalfa and many others. Unfortunately, honeybees have faced a plague of pathogens that have caused their populations to dramatically decline. Commercial beekeepers have struggled to keep up with the ever-rising demand for crop pollination due to epidemics like Varroa destructor and Colony Collapse Disorder. Due to the damage of Colony Collapse Disorder in recent years, American beekeepers have been unable to meet the pollination demands of crops like California almonds (Packer 9). Major losses in managed honeybee colonies have created fear for the future of agricultural crops and our nation’s accessibility to nutritional foods, causing experts across North America to question whether honeybees will continue to be reliable agricultural pollinators. Our dependence on honeybees in modern agricultural models has built a popular misnomer that honeybees are the only pollinators available for the job: but are there other, more reliable, options?

IMG_5025

Photo by: Susan Anderson

There are 19,500 described wild bee species in the world that specialize in pollination (Packer 15). There are many different species of honeybees alone, and it is often disputed where their wild origins may have come from, but they can be found natively throughout Europe, Asia, and parts of Africa. It is commonly unknown that honeybees are not native to North America. Thousands of other bees find their native home among American wildflowers, but honeybees are not one of them. Despite their false representation as American pollinators, their domesticated partnership alongside industrial agriculture has made them the dominant pollinator researched and known to the public. As we reassess the failing infrastructure of honeybee-dependent agriculture, the possible role of native pollinators is in question. If there is a sufficient population of native pollinators to meet agricultural demands, the use of wild pollinators could potentially lead to more ecologically and economically sustainable pollination practices. Unfortunately, wild pollinators face many challenges within both wild and agricultural landscapes due to independent pressures within the two differing habitats, both stemming from a honeybee-dominated system unable to support native populations.

Honeybees themselves create many of the challenges facing native bees today. Feral and domesticated honeybee colonies have become so common throughout North America that they have come to dominate pollen and nectar sources, creating detrimental pressures on native pollinators. Honeybees were brought to North America by English colonials on their ships crossing the Atlantic. They were first introduced to Jamestown, Virginia in the early 1600’s. Along with other important foods, customs, values, and items from their every day lives, the colonials brought honeybees to pollinate their crops, provide honey as their sweetener, and make candles out of beeswax to light their homes (Honeybees). Similar to many other unintentionally invasive species introduced by colonization, the honeybee spread wide and fast. Due to the social structure of their colonies, honeybees quickly became a dominant ecological presence amongst the majority of other pollinator species who remain solitary or in small communities. With the power of numbers, a honeybee colony is able to protect its nest, forage for food, and foster young, all at the same time. This social characteristic, unique to super organisms like social bees and ants, generally out competes solitary insects for food and nesting sites within every ecosystem around the globe. Although honeybees are never aggressively competitive with other pollinators, their large foraging force gathers disproportional amount of available nectar sources. In ecosystems carefully evolved to provide balanced nectar sources for available pollinators, the large nectar demand of a honeybee colony can suddenly starve out local species.

Concerned about the honeybee’s effect on native bumblebee populations, nature writer and Ph.D. biologist, Bernd Heinrich formulated an equation that demonstrates the effects of limited resource availability among pollinator species and strong honeybee colonies. A strong honeybee colony in the US produces an average of 539 pounds of honey each year to sustain itself. According to the needs of a native bumblebee colony and available nectar resources, Heinrich calculated that for every gram of honey produced by honeybees competing in the same ecosystem as bumblebees, there would be about .16 fewer bumble bees reproduced due to a lack of resources. Therefore, one honeybee colony could reduce the reproductives inside bumblebee colonies by 38,400, which would roughly equate to 102 less colonies each season due to the honeybee’s domineering foraging abilities (Buchmann 173). Heinrich’s work demonstrates a projected scale in which honeybees affect native pollinator populations. A lack of historical survey has disabled tested quantification of the honeybee’s impact, but research has noticed a decline in many pollinator species throughout the world due to the pressures of decreasing habitat. Even without official numbers to quantify their impact, it is well acknowledged that the foraging force of feral and domesticated honeybees honeybees is a prevalent pressure on stressed populations of native pollinators.

butterflies_tn

CU Museum of Natural History, Entomology Collections

As native pollinator populations decline, experts worry not only about the diversity of pollinator species, but the longevity of many pollination-dependent plants as honeybees alone cannot maintain entire floral communities. As localized species that have evolved closely alongside the flora within their environments and under local environmental conditions, native pollinators tend to be better pollinators than honeybees. Honeybees cannot always trigger more complex flower reproductive parts, and they mix nectar and saliva with their pollen as they carry it from flower to flower. These behaviors make it more difficult for pollen grains to transfer from flower to flower. Wild bees on the other hand carry pollen loosely on their back legs or stomachs, and have close relationships with local plant species, making them specialists at properly triggering successful pollination. Researchers found that honeybees in Alberta, Canada pollinate one in every thousand alfalfa flowers they visit properly, while alfalfa leaf cutter bees have a 100% success rate (Packer 21). Bumble bees are known to be hardy pollinators, they stay out working in cold and even wet conditions long after honeybees retreat to the hive. Some plants, like tomatoes, require “buzz pollination,” an act of shaking or buzzing the flower, only performed by bumble bees to release pollen grains. The ecological value of native pollinators, due to their localized specialization and diversity, proves itself similarly within agricultural crops. We often forget agricultural landscapes are controlled ecosystems in themselves. With properly balanced resources and relationships, preferred species thrive.

Native pollinators are often worthy contenders in agriculture, but they have been pushed out by the homogenous practice of industrial agriculture and its undying allegiance to honeybees. Our agricultural landscape is no longer homologous with native ecosystems. Western agriculture demands resources beyond that of a natural ecosystem, and does not foster life systems. Although this is a disheartening reality, American populations depend upon the food produced by these commercial agricultural systems. The propagation and use of native pollinators could manage the failing services of honeybees, but are the requirements of Western food production truly dependent upon honeybees as imported pollinators? Could native pollinators feed the United States?

Within intensively developed agricultural landscapes native pollinators have been largely erased due to mono-cropping, which provides nectar only one time a year, inhospitable nesting grounds, and the common use of pesticides. Available natural habitat for bees is often as low as 8% in most agricultural landscapes. Laurence Packer, a professor and melittologist at York University surveyed the viability of native pollinators within small blueberry farms of Nova Scotia. He found that wild bee populations in his study area were abundant enough to meet the pollination demand. However, Packer’s research also concluded that the blueberry field size had to be small enough for pollinators residing in neighboring natural land to reach crops at the center of cultivated land (Packer 20). Nova Scotia blueberry fields have enough native pollinators, but their viability depended upon nearby wild land and appropriate scale. To better define agricultural landscapes that can support wild pollination, Winfree et al. surveyed wild pollinators on conventional farm land in central New Jersey and east-central Pennsylvania in an additional, more detailed, study. The study found adequate presence of pollinating wild bees to produce a viable crop yield at 91% of the commercial farms within the study (Winfree 11090). Winfree et al. suggest that the defining factor in their study on Northeastern farm pollinator abundance is due to the heterogeneous agricultural landscape, offering biodiversity within nectar and pollen sources within 0.3km of agricultural land (Winfree 1112). The relatively close natural land patches coincide with Packer’s conclusions that nearby habitat patches are necessary to foster strong populations of native pollinators. A study done on Costa Rican coffee farms by Taylor Ricketts, professor of ecological economics at the University of Vermont, concluded that similar wild habitat patches resulted in higher yielding coffee plants because of available wild pollination services. In the Costa Rican study, researchers calculated the economic value of these patches according to the value of provided pollination services as equal to other major competing land uses such as cattle grazing or crop rearing (Ricketts 12582).

IMG_4959

Photo by: Susan Anderson

Unlike the sprawling mono-cropped grid of agricultural regions like California’s Central Valley, the patchwork farm-scape laced between wild deciduous forests of the Northeast within Winfree’s study or the Costa Rican’s coffee farms surrounded by wild land within Ricketts’ study, provided sufficient nesting and foraging habitat to foster wild pollination. While the observed Northeastern and Costa Rican farms tend to be smaller than those found to the west, they are still producing on a commercial scale. In one of his essays within Home Economics Wendall Berry discusses an understanding of proper scale; “A proper human sound, we may say, is one that allows other sounds to be heard. A properly scaled human economy or technology allows a diversity of other creatures to thrive” (Berry 16).

According to Winfree and Packer’s work, wild pollinators could be successfully implemented in agricultural systems with small adjustments to landscape scale and shape. This shift in agricultural practice would be advantageous for agricultural and ecological systems alike. Packer finds the inclusion of native pollinators essential for the long-term sustainability of agriculture, as resilience through diversity insures the system’s ability to return to a stable state after disturbance. He urges, “Just as we protect our finances by not putting all our funds into a single stock, we should hedge our pollination bets by not relying upon the activities of a single species” (Packer 13). If another epidemic were to affect honeybees on the scale of Colony Collapse Disorder, farm-scapes that provide heterogenous nectar sources, close enough to natural bee habitat, and practice appropriate pesticide use would be the only farms able to produce a viable crop. Packer’s suggestion does not imply that we rid our landscapes of honeybees all together, but implement practices that foster many different kinds of pollinators. In light of declining honeybee populations, the honeybee’s ecological impact on native species, and their often sub-par pollinating abilities, it would be wise to deepen the pool of pollinator diversity. Implementing native pollination would be advantageous for agriculture, but this shift would depend on cooperation with local ecosystems. The structure of crop land would need to adjust to the needs of the pollinators, requiring a strong paradigm shift within industrial agriculture.

bee_tn

CU Museum of Natural History, Entomology Collections

In order to practice wild pollination, the physical structure of the farm would have to incorporate or reestablish wild land within smaller plots of managed land. The use of pesticides and herbicides would have to drastically diminish if not disappear all together. The lines between farm land and forest would have to melt into one-another as partner ecosystems, replacing the vast desserts of orange, almond, or blueberry. Farmers in India actively manage wild pollinator populations for crop production without the aid of domesticated bees in this way. Growing crops like cardamom and coffee together that flower at different times of the year, but attract the same kinds of bees insures a continual presence of needed pollinators. These Indian farm landscapes also provide native shade trees, providing nectar sources in the gap seasons and nesting habitat for pollinators (natural 8). Modeling our agricultural landscapes to be similar to these Indian farm-scapes would drastically change our relationship to agricultural land. The agriculture that feeds most of us today is rooted in industrial ideals. Industrial traditions of expansion, production, and efficiency at the cost of exploitation have steered the shape of agriculture since the industrial revolution. A prominent result of industrialization has been a dramatic decline in biodiversity. Pollinator ecologist and author, Stephen Buchmann reflects on the loss of biodiversity, “A biologically rich place is rich in relationships as well as in species. Conversely: the loss of biodiversity is always more than the simple loss of species; it is also the extinction of ecological relationships” (Buchmann 24). To incorporate the strength of biodiversity into our landscapes, our relationships will need to become equally diversified.

Beyond a structural shift, the industry would have to support an ecological solution, embracing cooperation over domination. While honeybees can be moved around the country and manipulated under domestication, native pollinators must be invited in, on their own will, to participate under conditions defined by their needs. In the end, to preserve pollinators as foundational species within ecological systems and as necessary components within American agriculture, we must build new relationships with our landscapes to foster viable habitats for pollinators as cooperative members of a larger, corresponding system.

photo

For more info about native pollinators, please visit Seneca’s website:  http://www.urbanpollinationproject.com

Works Cited:

Berry, Wendell. “Getting Along with Nature.” Home economics: fourteen essays. San Francisco: North Point Press, 1987. 6-20. Print.

Buchmann, Stephen L., and Gary Paul Nabhan. “New Bee on the Block.” The forgotten pollinators. Washington, D.C.: Island Press [for] Shearwater Books, 1996. 169-185. Print.

Eilers, Elisabeth , Claire Kremen, Sarah Greenleaf, Andrea Garber , and Alexandra Klein . “Contribution of Pollinator-mediated Crips to Nutrients in the Human Food Supply.” PLoC ONE 6.6 (2011): n. pag. PLoS ONE. Web. 18 July 2012.

“Honeybees.” native bee conservancy . N.p., n.d. Web. 6 May 2013. <www.nativebeeconservancy.org/girl-scouts-2/girl-scouts/about-honey-bees/>.

“natural pollination strategies for agricultural systems .” UPDATE, Center for Conservation Biology Stanford University 12.1 (1999): 8. Print.

Packer, Laurence. Keeping the bees: why all bees are at risk and what we can do to save them. Toronto: HarperCollins, 2010. Print.

Ricketts, Taylor H., Gretchen C. Daily , Paul R. Ehrlich , and Charles D. Michener . “Economic Value of Tropical Forest to Coffee Production.” PNAS 101.34 (2004): 12579-12582. http://www.pnas.org/cgi/doi/10.1073/pnas.0405147101. Web. 10 June 2013.

Spivak , Marla , Eric Mader, Mace Vaughan , and Ned Euliss. “The Plight of the Bees.” Environmental Science and Technology 45.1 (2011): 34-38. Print.

Winfree , Rachael, Neal Williams , Jonathan Dushoff, and Claire Kremen . “Native Bees Provide insurance against ongoing honey bee losses.” Ecology Letters 10 (2007): 1105-1113. Print.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s