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There has been a lot of publicity in recent years about growers battling glyphosate-resistant pigweed in soybean and cotton crops. But pigweed isn't the only weed resistant to glyphosate. New research published in the journal Weed Science shows certain populations of junglerice (Echinochloa colona) are now among a growing number of weeds resistant to the herbicide.

Junglerice is a weedy grass that grows in rice, corn and vegetable crops, in gardens, on roadsides and along waterways—primarily on the U.S. West Coast and in the South. Populations of junglerice resistant to multiple herbicides have previously been found in Arkansas, California and Mississippi, but glyphosate wasn't among them. Now, though, new glyphosate-resistant populations have emerged in Mississippi and Tennessee.

Their study showed a glyphosate-resistant population of junglerice discovered in Mississippi was four times more resistant to the herbicide than susceptible populations, while a population in Tennessee was seven times more resistant.

The world's most widely used weed killer may also be indirectly killing bees. New research from The University of Texas at Austin shows that honey bees exposed to glyphosate, the active ingredient in Roundup, lose some of the beneficial bacteria in their guts and are more susceptible to infection and death from harmful bacteria.

Because glyphosate interferes with an important enzyme found in plants and microorganisms, but not in animals, it has long been assumed to be nontoxic to animals, including humans and bees. But this latest study shows that by altering a bee's gut microbiome -- the ecosystem of bacteria living in the bee's digestive tract, including those that protect it from harmful bacteria -- glyphosate compromises its ability to fight infection.

The findings are published this week in the journal Proceedings of the National Academy of Sciences.

"We need better guidelines for glyphosate use, especially regarding bee exposure, because right now the guidelines assume bees are not harmed by the herbicide,"... "Our study shows that's not true."

The researchers exposed honey bees to glyphosate at levels known to occur in crop fields, yards and roadsides. The researchers painted the bees' backs with colored dots so they could be tracked and later recaptured. Three days later, they observed that the herbicide significantly reduced healthy gut microbiota. Of eight dominant species of healthy bacteria in the exposed bees, four were found to be less abundant. The hardest hit bacterial species, Snodgrassella alvi, is a critical microbe that helps bees process food and defend against pathogens.

The bees with impaired gut microbiomes also were far more likely to die when later exposed to an opportunistic pathogen, Serratia marcescens, compared with bees with healthy guts. Serratia is a widespread opportunistic pathogen that infects bees around the world. About half of bees with a healthy microbiome were still alive eight days after exposure to the pathogen, while only about a tenth of bees whose microbiomes had been altered by exposure to the herbicide were still alive.

"It's not the only thing causing all these bee deaths, but it is definitely something people should worry about because glyphosate is used everywhere," said Motta.

Native bumble bees have microbiomes similar to honey bees, so Moran said it's likely that they would be affected by glyphosate in a similar way.

Erick V. S. Motta el al., "Glyphosate perturbs the gut microbiota of honey bees," PNAS (2018).

The world’s most used weedkiller damages the beneficial bacteria in the guts of honeybees and makes them more prone to deadly infections, new research has found.

Previous studies have shown that pesticides such as neonicotinoids cause harm to bees, whose pollination is vital to about three-quarters of all food crops. Glyphosate, manufactured by Monsanto, targets an enzyme only found in plants and bacteria.

However, the new study shows that glyphosate damages the microbiota that honeybees need to grow and to fight off pathogens. The findings show glyphosate, the most used agricultural chemical ever, may be contributing to the global decline in bees, along with the loss of habitat.

“We demonstrated that the abundances of dominant gut microbiota species are decreased in bees exposed to glyphosate at concentrations documented in the environment,” said Erick Motta and colleagues from University of Texas at Austin in their new paper. They found that young worker bees exposed to glyphosate exposure died more often when later exposed to a common bacterium.

Other research, from China and published in July, showed that honeybee larvae grew more slowly and died more often when exposed to glyphosate. An earlier study, in 2015, showed the exposure of adult bees to the herbicide at levels found in fields “impairs the cognitive capacities needed for a successful return to the hive”.

“The biggest impact of glyphosate on bees is the destruction of the wildflowers on which they depend,” said Matt Sharlow, at conservation group Buglife. “Evidence to date suggests direct toxicity to bees is fairly low, however the new study clearly demonstrates that pesticide use can have significant unintended consequences.”

Prof Dave Goulson, at the University of Sussex, said: “It now seems that we have to add glyphosate to the list of problems that bees face. This study is also further evidence that the landscape-scale application of large quantities of pesticides has negative consequences that are often hard to predict.”

Hexenshexshul wrote:Hi everyone,
I would like to get the inevitable thread about Bayer Crop Science started. But first I would like to know if anyone is even aware of Bayer Crop Science, before I get to typing out long and exhausting posts.

jedrider wrote:

Hexenshexshul wrote:Hi everyone,
I would like to get the inevitable thread about Bayer Crop Science started. But first I would like to know if anyone is even aware of Bayer Crop Science, before I get to typing out long and exhausting posts.

You mean, Monsanto. Of course. They're now the same company. But, that's all I follow. I presume their franken-crops are doing well and that's how they intend to double yields by introducing more of them to large scale farming.

jedrider wrote:I don't know. These companies legacies seem complicated.

Five things to know about Bayer and Monsanto
https://phys.org/news/2019-03-bayer-monsanto.html

But, it's very simple if you just think Franken-Food.

According to Vice Minister of Agriculture Victor Suárez, Mexico wants to phase out glyphosate and GMO corn imports because the Mexican government is "committed to a fair, healthy, sustainable, and competitive agri-food system" and to "intensively promote agroecological and sustainable practices and reduce the use of agrochemicals."

Suárez says the main reasons for Mexico's bans are growing concerns about the safety of glyphosate and GMO contamination threats to Mexico's staple and sacred crop—corn.