Pollinators in Agriculture

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Pollinator Decline – Why does it matter and what can we do?

by Joanna Voigt

By now you’ve probably read or heard something about the pollinator crisis.  From dwindling Monarch butterfly populations whose over-wintering numbers this year were the lowest on record, to the alarming effects of Colony Collapse Disorder on honey bee colonies, to massive bumble bee die-offs on the West coast due to pesticide poisoning, news of pollinator peril has been pervasive in recent years.

Habitat loss, increased use of pesticides and other chemicals, and introduced diseases and pests all play a role in pollinator decline.  In 2000, the Convention on Biological Diversity declared a “pollinator crisis” and implemented an International Pollinator Initiative aimed at stemming the tide of the decline.  In the years since, awareness of the pollinator crisis has increased but pollinators continue to struggle.  New threats continue to plague pollinators, causing alarm and keeping pollinator decline a recurring news headline.  And, well it should be.  According to a Food and Agriculture of the United Nations report, “Pollination is a keystone process in both human managed and natural terrestrial ecosystems.  It is critical for food production and human livelihoods, and directly links wild ecosystems with agricultural production systems.”

Without pollinators, our food supply would look dramatically different.

According to Claire Kremen, international conservation biologist and professor at University of California, Berkeley in an article on EarthSky, “You can thank a pollinator for about one out of every three mouthfuls [of food] that you take every day.”

In the absence of pollination, many plants cease to produce the fruits, vegetables, berries, nuts and seeds we rely on for food.  Apples, apricots, avocadoes, lima beans, blackberries, blueberries, cabbage, canola, citrus, cotton, cucumber, eggplant, kiwi, mango, melons, peaches, pears, peppers, pumpkins, strawberries, sunflowers, squash, and watermelon are all pollinator-dependent crops.

Even crops that don’t require pollination are often found to have higher yields when visited by bees or other pollinators.  Foods that fall into this category include tomatoes, coffee, and soybeans, to name a few.  Studies show that pollination results in higher quality produce, and that pollination may protect crops from pests (FAO 2009).

There are over 100,000 species of invertebrate pollinators including bees, butterflies, moths, flies, and beetles, and over 1000 species of vertebrate pollinators including birds, mammals, and reptiles. Insects pollinate 75% of human food crops, worldwide, contributing $210 billion in agricultural earnings, according to Richard Conniff in an article in Yale Environment 360.  In the US, European honey bees, Apis mellifera, are the primary provider of pollination services for agriculture, with an economic value of $17 billion per year.

Honey bees are not native to North America, but were introduced for honey production in the 1600s.  Although honey bees are domesticated, their proclivity for swarming resulted in a robust wild population of Apis mellifera that thrived in the US until the combined effects of tracheal and Varroa mites effectively decimated their populations in the 1990s.  In 2006, a mysterious affliction, later termed Colony Collapse Disorder (CCD), began sweeping through the nation’s domesticated honey bee populations.  Ultimately, CCD wiped out nearly one-third of all managed hives, leaving a distinct shortage of pollinators to carry out the pollination services required for crop production, and prompting a closer look at the potential of native pollinators to provide pollination services.

Native pollinators can be highly efficient pollinators and have some advantages over honey bees, such as a wider range of foraging behaviors and greater latitude of climatic conditions in which they will forage.  However, native bees face their own set of struggles to survive, with many species’ numbers having been on the decline for many decades.  A study of four North American bumble bee species revealed that their populations had declined by 96% over the past century.

Presently, native pollinators contribute roughly $3 billion to pollination of human food crops in the US, according to the Xerces Society for Invertebrate Conservation, and many researchers feel that this number could and should increase significantly.  Efforts to attract and promote native pollinators in agricultural settings are on the rise, worldwide.  In addition to helping ensure sufficient pollination of human food crops, there are other important reasons to protect and encourage native pollinator populations.

Pollinators play a vital role in preserving biodiversity.

Biodiversity is critical to functioning ecosystems, which provide services that regulate the health of our land and water, and the air we breathe.  Ecosystem services include moderation of weather extremes and their impacts, mitigation of drought and floods, nutrient cycling, erosion protection, detoxification, pest control, soil health preservation, climate stability, purification of water and air, regulation of disease carrying organisms, and pollination of crops and natural vegetation.

Pollinators are considered a “keystone species,” meaning they have a disproportionately large impact on biodiversity and ecosystem function in most terrestrial ecosystems, compared to other species.  In a given ecosystem, as a keystone species fares, so fares the rest of the ecosystem.  Because the majority of the earth’s flowering plants require pollination in order to produce seeds, entire ecosystems rely on pollinators and would collapse without their services.  In other words, biodiversity and ecosystem function are inextricably linked to pollinators.  The dire shape of pollinators is a strong indicator that all is not well in the environment, and should sound as a warning to right the course.

Agricultural activities play a major role in pollinator decline.

Loss of habitat due to large-scale conversion of natural areas to cropland and pastures is the primary culprit in pollinator population decline and has caused dramatic declines in plant, animal, and other insect diversity, as well.  In Kansas, 90% of the state’s 52 million acres have been converted to farmland, with 57% in monoculture crops and 29% in pastures, resulting in a homogenized landscape devoid of habitat for pollinators and other wildlife.

Pesticides and other chemicals used in agriculture also play a significant role in declining pollinator populations.   Neonicotinoids are a class of systemic insecticides, introduced to the market in the 1990s.  By 2005, neonicotinoids had gained 16% of the market share, making them the fastest-growing class of insecticides in the history of synthetic insecticides.

Neonicotinoids target sucking insects such as fleas and aphids, and are applied as foliar sprays, seed coatings and soil drenches.  They have been shown to cause impaired communication, disorientation, decreased longevity, suppressed immunity and disruption of brood cycles in honey bees (PANNA 2012).  Misuse of Safari, a neonicotinoid insecticide was responsible for the massive bumble bee (and other insects) die off in Wilsonville, Oregon, in June 2013.

Neonicotinoids are highly persistent and have been shown to accumulate in the environment, and have been found in beeswax, pollen, honey and bee bodies.  They are approved for use on stone fruits, nuts, canola, sunflowers and corn, as well as for gardens and lawns and as a topical flea treatment for pets.

The role of farmers and ranchers in pollinator conservation.

While agricultural activities can be implicated in the decline of pollinator populations, they also stand to play a significant role in their recovery.  A diversified, ecologically based farm system that includes practices such as intercropping, agroforestry, insectary strips, cover crops, fallow fields, border planting, riparian buffers, and woodlots, meadows and forests, can greatly benefit pollinators by providing natural habitat areas and reducing the use of harmful pesticides and other chemicals.

A study by Claire Kremen and Albie Miles from the University of California, Berkeley, focused on ecosystem services in biologically diversified versus conventional farming systems and showed that, “As with other components of biodiversity, pollinator communities were richer and more abundant with agri-environment management schemes (primarily organic).”

A number of recent studies have shown that organic management has a significant impact on pollinator abundance and species richness.  One study of 42 wheat fields in Germany demonstrated that organic management increased pollinator richness by 60% and abundance by 130 to 136%.  Increasing the proportion of organic fields in the landscape from 5 to 20% further increased pollinator richness and abundance by over 60% on both organic and conventional farm fields, indicating that abundance of floral-rich habitat is the primary driver of pollinator richness, and that planting “flower-rich hedgerows, grassy borders, or in-field insectary strips” is an effective management technique for increasing pollinator populations and diversity (Kremen 2012).

Farmers and ranchers are in the unique position of having the potential to substantially impact the future of pollinators.  Because of the enormous amount of land that is devoted to agricultural uses, changes away from agricultural practices that harm pollinators and towards agricultural practices that benefit pollinators is the most critical piece of pollinator conservation puzzle.

 

Works Cited:

Food and Agriculture Organization of the United Nations (FAO).  2009. Bees and their role in forest livelihoods: A guide to the services provided by bees and the sustainable harvesting, processing and marketing of their products.  FAO.

Kremen, C., and A. Miles. 2012.  Ecosystem Services in Biologically Diversified versus Conventional Farming Systems: Benefits, Externalities, and Trade-Offs.  Ecology and   Society 17(4): 40.

Pesticide Action Network North America (PANNA). 2012.  Pesticides and Honey Bees: State of the Science.  http://www.panna.org/issues/publication/pesticides-and-honey-bees-state- science.  May 8, 2014.