Bee Alert: Is a Controversial Herbicide Harming Honeybees?

Yale Environment 360 By Michael Balter May 7, 2019

A honeybee pollinates a blossom in an almond orchard in McFarland, California. DAVID KOSLING/ USDA

A honeybee pollinates a blossom in an almond orchard in McFarland, California. DAVID KOSLING/USDA

Recent court cases have focused on the possible effects of glyphosate, found in Monsanto’s Roundup, on humans. But researchers are now investigating whether this commonly used herbicide could also be having adverse effects on the health and behavior of honeybees.

Is one of the world’s most widely used herbicides a danger not only to annoying weeds, but also to honeybees? While debates rage over whether certain powerful insecticides are responsible for so-called colony collapse disorder — or even whether bee populations are declining at all — recent research suggests that glyphosate, the active ingredient in weed killers such as Monsanto’s Roundup, could be having subtle effects on bee health.

Glyphosate has been in the news in recent months, but not for its possible harm to bees. Rather, some studies have suggested an association between exposure to glyphosate and higher risk of non-Hodgkin lymphoma (NHL), a cancer of the white blood cells. Glyphosate garnered headlines last August when a jury in California awarded groundskeeper DeWayne Johnson a massive judgement against Monsanto’s parent company, the German pharmaceutical giant Bayer. Johnson, along with more than 13,000 other plaintiffs, alleges that glyphosate caused his case of NHL.

But concerns about glyphosate are not limited to humans. Researchers have been accumulating evidence that glyphosphate may also be having deleterious effects on the environment and be harmful to fish, crustaceans, and amphibians, as well as to beneficial bacteria and other microorganisms in soil and water.

A University of Texas study reported evidence that glyphosate disrupts microorganisms in the guts of bees.

In recent years, a number of studies have concluded that glyphosate could also be hazardous to bees. Although the herbicide does not appear as toxic to bees as some other pesticides (notably neurotoxins known as neonicotinoids), researchers have found that glyphosate may impact bees in more subtle ways — for example, impeding the growth of bee larvae, diminishing bees’ navigational skills, altering their foraging behavior, or even disrupting their gut microorganisms, known as the microbiome.

The research is controversial because defenders of glyphosate use have long argued that it is benign in the environment. The herbicide is uniquely designed to target an enzyme that plants need to grow. That enzyme is essential to the so-called shikimate pathway, a metabolic process required for the production of certain essential amino acids and other plant compounds. However, the shikimate pathway is also used by some bacteria and other microorganisms, raising the possibility that glyphosate could have widespread and unexpected effects on a variety of natural organisms.

In a September study in the Proceedings of the National Academy of Sciences, Nancy Moran, an evolutionary biologist and entomologist at the University of Texas, Austin, and her coworkers found evidence that glyphosate disrupts microorganisms found in bees’ guts.

Monsanto's Roundup at a store in San Rafael, California. The product's manufacturer maintains that glyphosate is safe when used as directed.JOSH EDELSON/AFP/ GETTY IMAGES

Monsanto's Roundup at a store in San Rafael, California. The product's manufacturer maintains that glyphosate is safe when used as directed.JOSH EDELSON/AFP/GETTY IMAGES

Mature bees have eight dominant gut bacterial species. Those strains are responsible for such benefits as promoting weight gain and providing resistance to harmful pathogens. The University of Texas team found almost all of them declined when the bees were exposed to concentrations of glyphosate commonly found in the environment. Young worker bees exposed to glyphosate were more susceptible to dying from infections. Moreover, the gut bacteria were more sensitive to the effects of glyphosate if the bacteria possessed an enzyme known to play a key role in the shikimate pathway.

Bayer disputes research findings suggesting Roundup or glyphosate is hazardous to bees. Utz Klages, Bayer’s head of external communications, says the “good news is that honeybee colonies are not in decline and rumors of their demise are greatly exaggerated.” Klages notes that regulatory authorities in a number of countries, including the United States, Canada, and the nations of the European Union, “have determined that glyphosate is safe when used as directed.”

A number of studies have suggested that glyphosate is not highly toxic to bees, including research performed by Monsanto and several other agrochemical companies. That research considered the “realistic worst-case” exposures to the herbicide and found no significant effect on bee mortality. Similarly, a series of studies led by Yu Cheng Zhu, a research entomologist at the U.S. Department of Agriculture, concluded that glyphosate did not seem to kill bees outright. “We did not find an unusual number of dead bees after spraying a bee yard with Roundup a few times each year,” Zhu said.

Scientists have found that glyphosate appears to interfere with the growth and survival of honeybee larvae.

But Walter Farina, a researcher at the University of Buenos Aires in Argentina, says that the very fact that glyphosate is not immediately toxic to bees facilitates the harm it does. “Since glyphosate does not cause lethal effects, it can enter the colony and [be] assimilated by the younger individuals,” Farina says. “The negative effects of [glyphosate] are worse for younger bees, promoting an increased disorganization of the collective task within the hives.”

Farina and his team have looked at some of these effects in Argentina, where glyphosate is intensively used in agriculture. In a 2014 study, published in The Journal of Experimental Biology, they found that the “appetitive behavior” of honeybees — including how well they could detect sucrose and their ability to learn and remember where food sources were located — was significantly diminished after exposure to doses of glyphosate commonly found in farmlands.

In a second study, published in 2015 in the same journal, Farina’s team used harmonic radar to track how long it took honeybees to find their way back to their hives. They found that exposure to relatively low doses of glyphosate appeared to hinder the bees’ ability to navigate back to the hive, and concluded that glyphosate “impairs the cognitive capacities needed to retrieve and integrate spatial information for a successful return.”

A farmer in Argentina, where glyphosate is used intensively, sprays a soybean field in Entre Rios province in February 2018. PABLO AHARONIAN/AFP/ GETTY IMAGES

A farmer in Argentina, where glyphosate is used intensively, sprays a soybean field in Entre Rios province in February 2018. PABLO AHARONIAN/AFP/GETTY IMAGES

In other research, scientists have found that glyphosate appears to interfere with the growth and survival of honeybee larvae. For example, in a studypublished last year in the Journal of Agricultural and Food Chemistry, Pingli Dai of the Institute of Apicultural Research in Beijing, China, and his colleagues found that elevated exposures to glyphosate can lower both the weight of bee larvae and the larval survival rate. This study also showed that glyphosate markedly decreased the diversity and richness of bacteria in the larvae’s intestines, indicators of reduced resilience.

As concerns about how glyphosate may be affecting honeybees mount, researchers are getting a boost from funding agencies that see this as an important research avenue. In March, the National Science Foundation awarded nearly $1 million in grant money to researchers at Virginia Tech and Eastern Washington University to further study the honeybee microbiome.

Meanwhile, Moran, at the University of Texas, says her lab has done follow-up confirmatory experiments using antibiotics to target the honeybee gut bacteria, with similar results on bee mortality as in the previous experiments. She emphasizes that these results have little to say so far about how important a factor glyphosate might be in the declines in bee populations. “We have to say that we don’t know at this point,” she says. “Our results suggest that it is worth studying further, which is what we are doing, and hope others will do also.”

Better Almonds for Bees

The Xerces Society           December 10, 2014

Working with several major food companies, and one of the largest almond producers in the world, Xerces is developing a game-changing strategy for almond production right now in California's Central Valley.

Between much needed rain showers this week, our California habitat specialist Jessa Kay Cruz, is managing a project to install nearly 5 miles of hedgerows and wildflower meadows throughout a 1,000 acre almond orchard. Thousands of flowering, drought-tolerant, native California shrubs are being planted, and hundreds of thousands of wildflower seeds are being sown to create nectar-rich habitat to support the bees that pollinate almonds.

All of this is just step one. In the year ahead we will be installing a first-of-its kind wildflower cover crop system under the trees, developing reduced-risk pest management strategies, and expanding this model to more and more orchards. The net effect, we hope, will be a better landscape for bees in California's almond country.

The Xerces Society

My View: Look Past Pesticides to Study Pollinator Health

 Portland Tribune    By Jeff Stone & Scott Dahlsman    June 26, 2014

As fellow state Pollinator Health Task Force members, we were disappointed to read the piece written by Aimee Code and Scott Hoffman Black of the Xerces Society (Protect pollinators like our lives depend on it, guest column, June 19).

The column included a number of inaccurate claims. It also suggests that some members of the task force are more interested in banning a product they don’t like instead of actually looking for ways to improve pollinator health.

The concerns about pesticide use and potential effects on bees are very important to all pesticide users, but especially those involved in agriculture. Oregon farmers depend on bees to pollinate many of their crops, but also depend on pesticide tools to control destructive pests.

Similarly, commercial beekeepers rely on healthy crops to optimize their pollination services. This means that Oregon growers and beekeepers have a lot at stake in this conversation, and each share a vested interest in ensuring that protecting bee health and the use of pesticides are not mutually exclusive.

Bee health is important to all of us, and nobody wants to see adverse incidents that add to bee population declines. That being said, it is easy to let emotion drive the conversation around these issues. We should instead let science be our guide.

While concerns about pesticides and bees have been around for decades...

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General Mills, Whole Foods Generate Buzz for Bees

Marketing Daily   By Sarah Mahoney   June 23, 2014

Count Whole Foods and General Mills’ Cascadian Farms as the latest champions of the challenged honeybees. To raise awareness, Whole Foods stores are busy talking up the powers of pollinator with “Human Bee-In” events and “Give Bees A Chance” promotions. And General Mills, which launched Buzz Crunch Honey Almond cereal exclusively at Whole Foods Market stores nationwide back in April, says it is now donating $1 for every box sold, up to $100,000 to the The Xerces Society, an Oregon-based nonprofit and leader in pollinator conservation.

Whole Foods and Xerces say they will continue to share the buzz through July 1, raising awareness of the role bees play in food supply through a social media campaign.

The plight of the honey bee, a problem that has been baffling conservationists and farmers for almost a decade, gained additional attention last week, when President Barack Obama announced a task force to address the issue of rapidly diminishing honey bees and other pollinators. "Pollination is integral to food security in the U.S.," the announcement says, with pollinators, which also include vanishing Monarch butterflies and threatened species of bumblebees, affecting 90 commercially grown crops in North America, and adding some $24 billion to the U.S. economy. Honey bees account for $15 billion, and the number of managed honey bee colonies has fallen from 6 million hives in 1947 to 2.5 million today. Obama's budget recommends $50 million to encourage research.

Consumer brands, including Clorox Co.’s Burt’s Bees and GM’s Cascadian Farms, have adopted bees as a pet cause, partnering with Xerces and other groups. General Mills even has a bee sanctuary at its research farm, and has established bee-friendly habitats on 10 Minnesota farms, as well as next to Muir Glen tomato fields in California. (It’s also funding a 700-acre almond orchard near Fresno, Calif., to produce bee-friendly almonds.)

In years past, Whole Foods has dramatized the bee’s plight by erasing produce items from its shelves. This year, its Lynnfield, Mass., store turned the attention to the dairy aisle, taking away many products for a day to demonstrate how important bees and butterflies are to dairy farmers. The Austin, Tex.-based retailer is also donating $1 for every organic cantaloupe sold to The Xerces Society, and many participating brands are donning “Give Bees A Chance” signs, making with-purchase donations to Xerces, including Annie’sBarney ButterBurt’s Bees; Celestial Seasonings, and Luna.

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Bill Seeks To Halt Bee-Killing Pesticides in U.S.

Global Issues  By Matthew Charles Cardinale (Atlanta, Georgia) 7/29/13

ATLANTA, Georgia, Jul 29 (IPS) - Two Congressional Democrats have co-sponsored new legislation called the Save America's Pollinators Act of 2013 to take emergency action to save the remaining bees in the U.S., and in turn, the U.S. food supply.

At issue is the use of toxic insecticides called neonicotinoids. Recent studies suggest that at least four types of these insecticides are a primary cause of the massive decline in bee populations seen in the U.S. in recent years.3

It is estimated over 10 million beehives been wiped out since 2007, as part of a phenomenon known as Colony Collapse Disorder.

"Given that EPA allowed many of these insecticides on the market without adequate safety assessments and without adequate field studies on their impact to pollinator health, we feel it's time that Congress support a bill like the Conyers-Blumenauer bill, which would suspend the use of the neonicotinoids until EPA does the adequate science to prove that these neonicotinoids… are not harmful - and if they are harmful, to keep them off the market," Colin O'Neil, director for government affairs for the Centre for Food Safety, told IPS.

"One-third of food that's reliant on the honeybee pollination is really under threat, and threats to pollinators concern the entire food system," O'Neil said.

During the last winter alone, which began in 2012 and ended early this year, U.S. beekeepers lost 45.1 percent of the colonies they operate, with some beekeepers losing 100 percent, according to a government-sponsored study.

The European Union has already imposed a two-year moratorium on several types of neonicotinoids, after the European Food Safety Authority found in January 2013 that certain neonicotinoids were threatening Europe's bee populations.

In May 2013, the U.S. Department of Agriculture and U.S. Environmental Protection Agency (EPA) issued a joint study noting that, "Acute and sublethal effects of pesticides on honey bees have been increasingly documented, and are a primary concern."

The proposed legislation, by Rep. John Conyers and Rep. Earl Blumenauer, would require the EPA to suspend the use of at least four neonicotinoids, including imidacloprid, clothianidin, thiamethoxam, and dinotafuran.

The legislation would prevent the EPA from re-authorising the use of the chemicals as pesticides until the agency conducts a full review of the scientific evidence. It would have to determine there are no unreasonable adverse effects on bees or other pollinators or beneficial insects before allowing them back on the market.

Through their pollination activities, by which bees allow plants to reproduce, bees are responsible for over 125 billion dollars in global food production, including over 20 billion dollars in the U.S., according to the legislation's findings.

"Neonicotinoids cause sublethal effects including impaired foraging and feeding behavior, disorientation, weakened immunity, delayed larval development, and increased susceptibility to viruses, diseases, and parasites and numerous studies have also demonstrated acute, lethal effects from the application of neonicotinoid insecticides," the legislation states.

"Recent science has demonstrated that a single corn kernel coated with a neonicotinoid is toxic enough to kill a songbird," it says.

In June 2013, over 50,000 bumblebees were killed in Wilsonville, Oregon, as a direct result of exposure to a neonicotinoid that was used not as a pesticide, but to cosmetically improve the appearance of certain trees.

So many bees have already died in the U.S. that just one more bad winter here could cause a major food crisis, one U.S. Department of Agriculture scientist said in the recent report.

O'Neil notes the U.S. House recently approved an amendment to the Farm Bill that would establish an interagency consultation process on pollinator protection, and would establish a task force to address bee decline.

"Passage of that was the first indicator this summer that members of congress were really waking up to this issue," O'Neil said.

"We feel this bill is necessary because the bees are dying now, and we can't wait four years down the road to come to the conclusion that pesticides are killing bees," he said.

The Centre for Food Safety recently sent an email to their members asking them to contact Gina McCarthy, the new head of the EPA, to encourage her to take action to benefit bees. McCarthy is believed to be a strong proponent of environmental stewardship.

"We're hoping she's going to be a better steward of bee health at the EPA than her predecessor was," O'Neil said.

One of the neonicotinoids was conditionally registered for agricultural uses by the EPA in 2003, based on the fact that it was already registered as an insecticide for non-agricultural uses.

"So they allowed it to be conditionally registered without a field study on the condition this field study would still be received. Ten years later this requirement has never been met and the EPA continues to allow the use," O'Neil said.

Scott Hoffman Black, executive director of the Xerxes Society, an organisation that advocates on behalf of invertebrates, told IPS, "The important fact about , they're systemic, they're inside the plant. Others go straight on the plant, and the rain would wash it off after. It's in the roots, it's in the stem, it's in the flower, it's in the flower nectar."

When asked what would happen to te U.S. diet if there was a bee collapse large enough to eliminate pollination across the nation, Hoffman Black said that crops like wheat and corn, which do not require pollination, would still be available.

"Vegetables, fruits, nuts, all things that are highly nutritious and taste really good," would be eliminated, Hoffman Black said. "We would have rice and wheat.

"Our ecosystems are based on pollination of native bees; everything from grizzly bears to songbirds rely on food that rely on pollination," he said.


© Inter Press Service (2013) — All Rights ReservedOriginal source: Inter Press Service

Backyard Pesticide Use May Fuel Bee Die-Offs

This article by Brandon Keim appeared in Wired Science on 4/13/12 (Something to think about when planning our gardens.)

The controversy over possible links between massive bee die-offs and agricultural pesticides has overshadowed another threat: the use of those same pesticides in backyards and gardens.

Neonicotinoid pesticides are ubiquitous in everday consumer plant treatments, and may expose bees to far higher doses than those found on farms, where neonicotinoids used in seed coatings are already considered a major problem by many scientists.

“It’s amazing how much research is out there on seed treatments, and in a way that’s distracted everyone from what may be a bigger problem,” said Mace Vaughan, pollinator program director at the Xerces society, an invertebrate conservation group. 

The vast majority of attention paid to neonicotinoids, the world’s most popular class of pesticides, has focused on their agricultural uses and possible effects. A growing body of research suggests that, even at non-lethal doses, the pesticides can disrupt bee navigation and make them vulnerable to disease and...


Bees Have Been Pollinators for a Long Time (at least 100 million years)

We continue to celebrate National Pollination Week June 18-24, 2012

The following information is from Ethnobeeology:

Bees have been pollinators for a long time. This bee was preserved in amber at least 100 million years ago. It has specialized branched hairs useful for pollen collection, is thought to have nested in the ground, and is only ~3 millimeters long. Today there are over 20,000 species of bees on the planet and here in the USA we are celebrating with a National Pollinator Week.

The Xerces Society: There are simple and inexpensive things you can do to increase the number of native bees living on your land. Any work you do on behalf of pollinators will support other beneficial insects and wildlife. On the Xerces Society website you will find information on providing additional sources of food and shelter for native bees, additional practices you can adopt to enhance native bee habitat, and how to obtain financial support from government programs to do this work. 

Farming for Bees: Guidelines for Providing Native Bee Habitat on Farms 
By Mace Vaughan, Matthew Shepherd, Claire Kremen and Scott Hoffman Black (2007) This booklet outlines ways to protect and enhance habitat for native crop pollinators in the farm landscape. It includes advice on simple changes that can be made in farm management for the benefit of native bees, as well as information on how to enhance or provide important habitat features, such as nest sites and forage. Also included are case studies and links to plant lists across the country.

Attracting Native Pollinators: Protecting North America’s Bees and Butterflies, The Xerces Society's most recent book (2011), is available to purchase from the Xerces SocietyAttracting Native Pollinators is coauthored by four Xerces Society staff members Eric Mader, Matthew Shepherd, Mace Vaughan, and Scott Black in collaboration with Gretchen LeBuhn, a San Francisco State University botanist and director of the Great Sunflower Project.

Help today's bees survive. Prevent the bees from becoming a subject of only paleontological study. Thank you! 

Thank you to Ethnobeeology for providing this information.

Saving the Bumble Bees

By Kathy Keatley Garvey (Bug Squad - Happenings in the Insect World) 

It's sad to see and say, but like honey bees, the bumble bee population is declining, and that decline is alarming. Public awareness can help turn this around.

That's why we're glad to see that the Xerces Society for Invertebrate Conservation, based in Portland, Ore., has just published a free downloadable booklet titled Conserving Bumble Bees:


Visit the Kathy Keatley Garvey Bug Squad blog at:

Visit the Kathy Keatley Garvey website at:

Share the Buzz and Protect the Honey Bees


Honey bees and other pollinators are responsible for one out of every three bites of food we eat, yet US honey bee colonies are declining at an annual rate of 30% or more. Any way you look at it, that’s an unsustainable equation for a reliable food supply.

As an industry leader in natural and organic foods, Whole Foods Market® is passionate about raising honey bee awareness, taking action and helping our communities “bee the solution.”


Whole Foods Market® invites shoppers to “Bee Part of the Solution”

AUSTIN, Texas (June 13, 2012) – The honey bee may be small, but it plays a mighty role in pollinating more than 100 fruit and vegetable crops across the world.  With massive declines in honey bee populations, biodiversity and the future of our agriculture system and gardens are all being threatened. 

“Bees pollinate a third of our diet, yet they’re literally vanishing from their hives,” says Cheryl Galway, marketing director for Whole Foods Market’s South region. “Many people have no idea that honey bees play an essential role in our agricultural system. By raising awareness of the issue we hope to motivate people to take action and share many ways they can be a part of the solution.”