October 22, 2018 - Do you eat fruits and vegetables? What about nuts? If so, you can thank an insect pollinator, usually a honey bee. These small insects play a major role in pollinating the world’s plants, including those we eat regularly. They also increase our nation’s crop values each year by more than 15 billion dollars.
“You can bet that a majority of the fruits and vegetables that are in the produce aisle are there because some insect, most likely a bee, provided pollination services,” said USGS research ecologist Clint Otto.
However, critical honey bee and wild bee populations in the United States have been declining in recent years, creating concern about the future security of pollination services for agricultural crops.
Enter the USGS honey bee helpers. In a recent video, Otto, USGS biologist Matthew Smart, and their colleagues at the USGS Northern Prairie Wildlife Research Center in Jamestown, North Dakota, discuss their research on land use and pollinator health in the northern Great Plains. This research will be useful in equipping land managers and policy makers with the best-available science to improve forage and habitat for pollinators in a part of the country that is undergoing rapid land-use change.
Tiny Titans, Weighty Work
Originally imported from Europe in the 17th century, honey bees are essential to maintaining food production in North America today. According to the U.S. Department of Agriculture, they pollinate more than 100 U.S. crops and help provide one out of every three bites of food Americans eat.
“If we didn’t have migratory commercial honey bees, our dinner would look a lot less colorful and diverse,” said Smart.
Honey bees have another sweet superpower: making honey. They live and work in highly collaborative, social colonies with a sole reproducing queen, and they make honey by storing nectar from flowering plants in their hives for use during food scarcities.
“The average honey bee colony will gather roughly 40 pounds of pollen and 265 pounds of nectar from the local environment every year,” Otto said.
Bees can collect such large quantities of resources because they forage across a vast area, flying six miles or more away from their hives in search of flowers. When the conditions are right, a honey bee colony can collect several pounds of nectar in a single day.
Honey bees in the northern Great Plains are of critical importance to the commercial beekeeping industry and to the diversity of U.S. crops. Over the summer, beekeepers bring their bees to the region’s rich foraging habitat, where the bees feast on pollen and produce honey. The colonies then go on to pollinate many crops throughout the country, notably almonds in the Central Valley of California.
Despite their might, honey bees are in trouble. The number of managed hives in the United States has decreased by about 50 percent since the 1950s due to factors such as diseases, parasites, habitat loss, pesticide exposure, and shifting markets and consumer demand for honey. In recent years, beekeepers have experienced an average total loss of 30 percent of colonies annually, and in 2013-2014 this number increased to 34 percent – a damaging sting.
Mites and Maladies
Bees are subject to an increasing number of stressors such as pests, diseases, and pesticides. A parasitic mite called Varroa destructor is one of the most destructive honey bee pests. Varroa mites attach to immature and adult bees and feed on the bees’ blood. As a result, the honey bees’ lifespan is reduced and they may be subjected to life-threatening viral invasions.
Furthermore, colony collapse disorder, the cause of which is unknown, affects European honey bees and has also been recorded across the United States. The primary symptom of the disorder is no or low numbers of adult honey bees in a hive, with no dead bees present. Meanwhile, the queen and immature bees are present and honey is in the hive.
Land-use changes that decrease flower abundance can also affect bee health and pollination services. Midwestern states are losing crucial native grasslands and conservation lands that have historically provided abundant flowers for honey bees and native pollinators. A significant amount of corn and soybean crops are being planted to meet growing demands, often replacing many of the region’s bee-friendly crops. Also, agricultural practices associated with these changes reduce pollinator forage availability.
This loss of plant diversity can directly affect the health of honey bees. Pollen is the sole source of protein for bee colonies, and each plant species provides different balances of amino acids, fats, vitamins, and minerals in its pollen. As plant species are lost, so is honey bee nutritional availability.
“You can eat crackers your whole life and still live, but you won’t be very healthy because you’re not getting all the vitamins and minerals that you need,” said Sarah Scott, a student researcher with the USGS. “It’s the same with bees.”
These land-use changes in the Northern Great Plains, which have resulted in reduced areas of pollinator-friendly grasslands in favor of corn, soybeans, and small grain crops, are negatively impacting the profitability of the beekeeping industry, according to a recent USGS study.
From 2015-2017, scientists with the USGS studied how summertime land use in North Dakota, South Dakota, and Minnesota affected bee health and apiary population size by the fall and subsequent spring. Apiaries are locations where honey bee colonies are kept. The researchers found that apiaries surrounded primarily by row crops like corn, soybeans, and small grains had approximately 6,000 fewer bees by the end of the growing season compared to those surrounded by grasslands.
California almond farmers frequently rent honey bee colonies from beekeepers in the Great Plains to pollinate their almond crops in the spring. Colonies with larger population sizes are worth more money to beekeepers when pollinating almonds. The scientists found that each high-quality grassland apiary could generate a total of $1,200 more per year from pollination contract fees with almond farmers than the low-quality apiaries.
“Our study demonstrates how fundamentally entwined the beekeeping and agriculture industries are and how land use changes in the Great Plains are felt across the country,” Smart said. “Each almond you eat has a very complex backstory that can be partially traced to the well-being of honey bees in the Great Plains.”
Also, many beekeepers split colonies at the end of pollinating season, meaning they divide their healthy colonies into smaller ones and provide each with a new queen bee. They may then sell their excess colonies to other beekeepers across the country. However, smaller, less robust colonies don’t generate as many splits, reducing beekeepers’ selling revenue. The study estimated that each high-quality apiary could generate about $2,900 more per year in splits than a low-quality one.
Since commercial beekeepers in the Northern Great Plains often operate thousands of colonies among hundreds of apiaries, these potential revenue losses add up dramatically. For example, 200 high-quality grassland apiaries housing 48 colonies each could be worth an additional $820,000 annually in pollination fees and splits compared to 200 low-quality apiaries.
To the Rescue
Raising baby bees and making honey within a colony takes teamwork. It also takes teamwork to protect bee populations. Partnering with commercial beekeepers in North Dakota, South Dakota, Minnesota, and Michigan, the USGS scientists are specifically studying honey bee and native pollinator habitat across the northern Great Plains. Their research addresses how diversity and abundance of pollen resources differ according to land use and the associated varying outcomes for honey bee colonies.
Otto, Smart, and USGS scientists Robert Scott Cornman and Deborah Iwanowicz also developed a genetic sequencing strategy for identifying bee-collected pollen. Development of this technique allows the USGS to quantify pollinator forage at a landscape scale at a fraction of the cost.
These researchers measure colony health, productivity, and survival of colonies in varying landscapes, while keeping track of Varroa mite infestation rates. The USGS collaborates with the USDA to evaluate how federal conservation program lands contribute to the honey bee diet during the summer. Information collected by the USGS helps the USDA evaluate the impact of their pollinator conservation programs and make informed management decisions about ideal seed mixes and future plantings.
Friends in High Places
This USGS research aligns with a past Presidential Memorandum on pollinators and the "National Strategy to promote the Health of Honey Bees and other Pollinators," created by the Pollinator Health Task Force. The goal of the strategy is to reduce wintertime honey bee colony losses to no more than 15 percent within 10 years, and to establish seven million acres of pollinator habitat through restoration or landscape enhancement.
“We have a great opportunity right now to affect change that can have a lasting impact on the fate of pollinators,” said Smart.
The USGS Researches Native Pollinators, Too
While the importance of a healthy pollinator population to agriculture is clear, pollinators are just as important to sustaining functioning ecosystems and food supplies for wildlife. The USGS works closely with federal, state, and other partners to model and better understand pollinator habitats and habitat requirements.
The USGS is also conducting inventories of native bees and other pollinators in protected areas, forests, and other land types throughout the United States. Furthermore, scientists developed an online tool that documents plant-pollinator interactions to support pollinator management and research.
For more information about USGS pollinator research, please visit the USGS Pollinators webpage.
This story was originally published on February 19, 2016, and updated on October 19, 2018.
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The Buzz on Native Bees Blog: Ecosystems - whether agricultural, urban, or natural – depend on pollinators, great and small.
Pollinator Partnership: The Pollinator Partnership is a non-profit 501(c)3 organization – the largest organization in the world dedicated exclusively to the protection and promotion of pollinators and their ecosystems.
North American Pollinator Protection Campaign (NAPPC): The NAPPC is a collaborative body of more than 120 diverse partners, including the USGS and the Department of the Interior. Scientists, researchers, conservationists, government officials, and dedicated volunteers are engaging in major programs to protect pollinators, to raise pollinator-related issues, and to benefit the health of all pollinators.
Monarch Joint Venture: The Monarch Joint Venture is a partnership of federal and state agencies, non-governmental organizations, and academic programs that are working together to support and coordinate efforts to protect the monarch migration across the lower 48 United States. The USGS is a member of the Venture.
USGS News Release: Native Bees Foraging in Fields Are Exposed to Neonicotinoid Insecticides and other Pesticides