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Beyond Honey Bees: Wild Bees Are Also Key Pollinators, and Some Species Are Disappearing
By Kelsey K. Graham
Declines in bee populations around the world have been widely reported over the past several decades. Much attention has focused on honey bees, which commercial beekeepers transport all over the U.S. to pollinate crops.
However, while honey bees are a vital part of our agricultural system, they are generally considered the chickens of the bee world—domesticated and highly managed for specific agricultural use. They are not native to North America and often can't be used as a surrogate for understanding what is happening with native wild bees—the focus of my research.
There are about 5,000 native bee species in North America. Many have shown no evidence of decline, and some are thriving in highly urbanized areas. But other species, including some that were previously common, are becoming harder and harder to find. As scientists work to understand bee decline, it is important to identify the unique roles that native bees play, and to identify threats specific to them.
One in every three bites of food we eat is made possible by bees. They pollinate almonds, apples, blueberries, squash, tomatoes and many other popular crops. They also pollinate alfalfa, which we feed to farm animals, so they support the meat component of our diet too.
We need bees for food security and to maintain healthy ecosystems. Bees pollinate flowering trees and wildflowers, which in turn provide food and homes for other animals and improve water, air and soil quality.
Along with honey bees, wild bees are also vital for crop pollination. Research has shown that the presence of wild bees increases yields across many types of crops. They often are more efficient at pollinating crops native to North America than honey bees. For example, a honey bee would have to visit a blueberry flower four times to deposit the same amount of pollen as a single visit from a bumble bee queen.
Wild bees have a unique way of extracting pollen from flowers called "buzz pollination." By shaking flowers at a certain frequency, more pollen will be released, thus allowing for more efficient pollination. Honey bees can't do this.
A sweat bee uses 'buzz pollination' to dislodge pollen grains from a flower. Bob Peterson
Bumble bees are particularly good at buzz pollination, so several species are now commercially managed. Increasing numbers of farmers who grow fruits, vegetables, tree nuts and flowers are now using either bumble bees alone or a mix of bumble bees and honey bees to pollinate their crops.
Bumble Bees in Distress
But some bumble bee species are in decline. The rusty patched bumble bee (Bombus affinis) once was distributed throughout the eastern U.S. and southeastern Canada, but now is found only in a few small populations in the Midwest. In March 2017, it became the first bee in the lower 48 states to be listed as an endangered species after its population shrank by an estimated 91 percent in 20 years. Other bumble bees, such as the American bumble bee (B. pensylvanicus) have declined more gradually.
Reasons for bumble bee decline include increased prevalence of pests and pathogens, poor nutrition and pesticide exposure. Many of these stressors are due to agricultural intensification, particularly in the Midwest. Traditionally, grassland prairies provided nutritionally dense, safe forage for bees. But most former prairie lands have been converted to corn and soybean fields or developed for commercial and residential use. As a result, bumble bees are increasingly exposed to pesticides and their food supply is shrinking.
Rusty patched bumble bee (Bombus affinis).USGS
Why are some species thriving while others are declining? Some research suggests that traits such as a narrow or specialized diet and large body size, are associated with decline. But much more research is needed to fully understand which traits make species vulnerable, and to identify species that are especially at risk.
There are 46 species of bumble bee in North America; the other native bees (4,954-plus species) are vastly different in size, color and life history traits. Because native bees are so diverse, it is hard to identify a primary cause for wild bee decline. But as with bumble bees, poor nutrition and pesticide exposure are likely culprits. We also know that the majority of native bees nest in the ground, so they are vulnerable when natural areas are converted to tilled agricultural fields or paved over. Providing safe nesting areas for native bees is therefore vitally important to their conservation.
Conversation of grasslands to large-scale monoculture farms in the Midwest and northern Great Plains has reduced suitable habitat for pollinators. USDA / ERS
Measuring Bee Abundance and Diversity
I am part of a team at Michigan State University, funded by the U.S. Department of Agriculture's National Institute of Food and Agriculture, that is working to fill in some of knowledge gaps about bees. Michigan has 465 documented bee species, each with unique life history traits It also has a diverse agricultural sector, ranging from specialty crops like apples, blueberries and tart cherries to large-scale commodity crops like corn and soybean. And Michigan habitats range from highly urbanized to pristine wilderness. This diversity helps us ask questions about how different landscapes affect the local bee community.
To determine how the state's bees are doing now, we need to know how abundant and diverse communities were in the past. Fortunately, Michigan has a rich history of surveying bees, dating back several decades. We are replicating these studies now to detect changes in bee communities.
Researchers collecting wild bees in Michigan with passive bowl traps and nets. Kelsey K. Graham / CC BY-ND
We are also sampling bees across different landscapes and regions to identify areas with low bee abundance or diversity where conservation efforts could have the greatest impact. But the only way to know whether these actions are effective is to track changes in bee communities going forward. Our project is providing an important baseline for future comparisons and assessments of conservation programs.
We are also monitoring the health of managed bumble bees and honey bees that provide pollination services to local crops. One strategy we are testing is whether management practices, such as wildflower plantings, can improve bee health.
Results from this project will provide the most complete assessment of bees in Michigan to date. Importantly, we are looking at all bee species, managed and wild, since they all play vital roles in maintaining a healthy agricultural system and ecosystem.
Reposted with permission from our media associate The Conversation.
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Global Banks, Led by JPMorgan Chase, Invested $1.9 Trillion in Fossil Fuels Since Paris Climate Pact
By Sharon Kelly
A report published Wednesday names the banks that have played the biggest recent role in funding fossil fuel projects, finding that since 2016, immediately following the Paris agreement's adoption, 33 global banks have poured $1.9 trillion into financing climate-changing projects worldwide.
By Patti Lynn
2018 was a groundbreaking year in the public conversation about climate change. Last February, The New York Times reported that a record percentage of Americans now believe that climate change is caused by humans, and there was a 20 percentage point rise in "the number of Americans who say they worry 'a great deal' about climate change."
England faces an "existential threat" if it does not change how it manages its water, the head of the country's Environment Agency warned Tuesday.
By Jessica Corbett
A new analysis revealed Tuesday that over the past two decades heat records across the U.S. have been broken twice as often as cold ones—underscoring experts' warnings about the increasingly dangerous consequences of failing to dramatically curb planet-warming emissions.
By Madison Dapcevich
Ask any resident of San Francisco about the waterfront parrots, and they will surely tell you a story of red-faced conures squawking or dive-bombing between building peaks. Ask a team of researchers from the University of Georgia, however, and they will tell you of a mysterious string of neurological poisonings impacting the naturalized flock for decades.
The initial cause of the fire was not yet known, but it has been driven by the strong wind and jumped the North Santiam River, The Salem Statesman Journal reported. As of Tuesday night, it threatened around 35 homes and 30 buildings, and was 20 percent contained.
The unanimous verdict was announced Tuesday in San Francisco in the first federal case to be brought against Monsanto, now owned by Bayer, alleging that repeated use of the company's glyphosate-containing weedkiller caused the plaintiff's cancer. Seventy-year-old Edwin Hardeman of Santa Rosa, California said he used Roundup for almost 30 years on his properties before developing non-Hodgkin's lymphoma.
"Today's verdict reinforces what another jury found last year, and what scientists with the state of California and the World Health Organization have concluded: Glyphosate causes cancer in people," Environmental Working Group President Ken Cook said in a statement. "As similar lawsuits mount, the evidence will grow that Roundup is not safe, and that the company has tried to cover it up."
Judge Vince Chhabria has split Hardeman's trial into two phases. The first, decided Tuesday, focused exclusively on whether or not Roundup use caused the plaintiff's cancer. The second, to begin Wednesday, will assess if Bayer is liable for damages.
"We are disappointed with the jury's initial decision, but we continue to believe firmly that the science confirms glyphosate-based herbicides do not cause cancer," Bayer spokesman Dan Childs said in a statement reported by The Guardian. "We are confident the evidence in phase two will show that Monsanto's conduct has been appropriate and the company should not be liable for Mr. Hardeman's cancer."
Some legal experts said that Chhabria's decision to split the trial was beneficial to Bayer, Reuters reported. The company had complained that the jury in Johnson's case had been distracted by the lawyers' claims that Monsanto had sought to mislead scientists and the public about Roundup's safety.
However, a remark made by Chhabria during the trial and reported by The Guardian was blatantly critical of the company.
"Although the evidence that Roundup causes cancer is quite equivocal, there is strong evidence from which a jury could conclude that Monsanto does not particularly care whether its product is in fact giving people cancer, focusing instead on manipulating public opinion and undermining anyone who raises genuine and legitimate concerns about the issue," he said.
Many regulatory bodies, including the U.S. Environmental Protection Agency, have ruled that glyphosate is safe for humans, but the World Health Organization's International Agency for Research on Cancer found it was "probably carcinogenic to humans" in 2015. A university study earlier this year found that glyphosate use increased cancer risk by as much as 41 percent.
Hardeman's lawyers Jennifer Moore and Aimee Wagstaff said they would now reveal Monsanto's efforts to mislead the public about the safety of its product.
"Now we can focus on the evidence that Monsanto has not taken a responsible, objective approach to the safety of Roundup," they wrote in a statement reported by The Guardian.
Hardeman's case is considered a "bellwether" trial for the more than 760 glyphosate cases Chhabria is hearing. In total, there are around 11,200 such lawsuits pending in the U.S., according to Reuters.
University of Richmond law professor Carl Tobias told Reuters that Tuesday's decision showed that the verdict in Johnson's case was not "an aberration," and could possibly predict how future juries in the thousands of pending cases would respond.