Glyphosate Is Not Harming Honey Bees Gut Microbiota

New study published in reputable journal finds that Monsanto’s global weedkiller harms honey bees. The paper ‘Glyphosate perturbs the gut microbiota of honey bees’ reports that bees fed glyphosate at concentrations chosen to mimic environmental levels lose beneficial gut bacteria, which then leaves them vulnerable to deadly infections. Glyphosate, arguably the world’s most hated chemical which is currently being blamed for just about every ailment known to man is now facing fresh demands for a ban based on this new research. The only problem is that this new study is fundamentally flawed and fails to even address whether changes observed in the bees gut microbiome play any part in its health or that glyphosate is responsible for anything at all. What’s worse it that it will most likely take time and attention away from the real causes of the declining bee (and other pollinators) population and create a scapegoat for self-righteous zealots, and those looking to push their agenda. 

Glyphosate is the active ingredient found in a range of broad-spectrum herbicide, including Monsanto’s RoundUp. The molecule kills plants by inhibiting an enzyme used in the synthesis of the aromatic amino acids phenylalanine, tyrosine, and tryptophan. The plant is then unable to produce proteins essential to growth and within several days the leaves begin to turn yellow and the plant dies. The enzyme it inhibits (EPSPS) is only found in plants and some microorganisms, and not in animals. Therefore, the herbicide should have a very low toxicity to honey bees and other pollinators.  

Pollinators are critical for both ecosystem function and crop production and have a estimated economic value of £130 billion globally. Here in the UK we have over 1500 species of pollinators including hover-flies, wasps, flies, beetles, butterflies, moths, and bees all of which contribute between £430 – £603 million to the UK economy every year. Out of the 250 species of bee in the UK 224 are solitary bee species, 25 are species of bumble bee, and only 1 is a honey bee. 

Bees and other pollinating insects are generally declining in number, with parallel declines in the plants that rely upon them, however these declines are not universal. Some are threatened whilst others are extending their ranges. In recent years a lot of energy has been focused solely on the global number of honey bees (Apis mellifera) with good reason. They are responsible for pollinating 70 of the 100 crop species that provide 90% of our food and, therefore, have a huge economic value. The humble honey bee has since become the cute symbol for some environmental groups of the natural world fighting for its survival, which makes sense in places like the UK where the bee is native, but not so much for North America. 

Western honey bee (Apis mellifera)

Honey bees were first introduced in North America in the 17th Century with the arrival of European settlers. They are, depending on how you look at them, either an invasive exotic species, or someones property, like livestock. They are bred by beekeepers for their honey and shipped around the continent to pollinate crops. This does not make their reported decline any less worrying or unworthy of investigation, it just means that their decline in North America is a agricultural/corporate issues rather then an environmental one as it is in the UK. I feel I need to stress here I am exclusively talking about Apis mellifera and not any other bee or pollinator species. 

Honey bees in recent years have been facing health challenges and in the UK their numbers have been on the decline for over 50 years. Because they play such a vital part in food production, potential causes of their decline have been extensively investigated. A number of factors – such as disease, parasites, loss of habitat, climate change, and pesticides – are thought to have contributed, but no single one seems to be solely responsible. Glyphosate, the world’s most used herbicide has been thoroughly investigated and shown, time and time again, to have a very low toxicity to honey bees. This is why this new study, claiming to show a glyphosate induced change in honey bee gut microbiome, has garnered a lot of attention – because it contradicts everything we know so far. 

The new study, which claims to show that relative and absolute abundances of dominate gut microbiota species are decreased in bees exposed to glyphosate, almost immediately lost my respect when it referenced research from a questionable paper. It said that “some evidence suggests that glyphosate affects non-target organisms, for example, changing the behaviour of honey bees” and quotes ‘Effects of sublethal doses of glyphosate on honeybee navigation’. This paper reports that bees fed a sucrose solution contaminated with glyphosate took a longer time to fly home. However, in reality, it did nothing of the sort. There sample size was too small, with some groups containing only one bee, they lost a quarter of their bees, they did not account for confounding factors, they found that bees fed the highest concentration of glyphosate were actually the fastest, and they only conducted two flights, yet proclaimed to show “long-term consequences” for bee learning following glyphosate exposure. For more information Iida Ruishalme wrote a fantastic blog post on the subject, which I highly recommend. I know it might seem like I am going off on a tangent here, but in my experience, I have found that papers that reference garbage studies are often garbage themselves. 

The ‘Glyphosate perturbs the gut microbiota of honey bees’ paper took hundredths of adult worker bees collected from a single hive and treated them either with 5mg/L glyphosate 10 mg/L glyphosate or a sterile sucrose syrup (control) for 5 days. 15 bees from each group were then sampled and the rest were reintroduced to the hive. A second sample was taken from each group 3 days after reintroduction when fewer than 20% of bees released were recovered. They then compared relative and absolute abundances of the gut bacteria from the sample taken 3 days earlier. They reported that the “effects of glyphosate exposure on the bee gut microbiome were more prominent at day 3, after treated bees were returned to the hive” however they only found these changes in the lower glyphosate concentration group and not the higher one. This, to me, is an immediate red flag, and shows that, more than likely, there is a fundamental flaw in their experiment method and that their results are probably just noise. 

They try to explain away their conflicting findings by referencing, once again, the paper ‘Effects of sublethal doses of glyphosate on honeybee navigation’. They state that “since bees exposed to glyphosate may exhibit impaired spatial processing, compromising their return to hives”, that the high concentration group “may have been less likely to return to the hive after foraging”. Essentially, at this point, they are cherry picking data and discarding anything that doesn’t align with their, quite clearly prefabricated, narrative. If they truly believed that glyphosate compromises honey bees’ ability to return home, why would they design an experiment that relies on large numbers of honey bees who have consumed glyphosate to find their way home?!?!

To round it all off, they finish this section with, “Since fewer than 20% of the bees reintroduced to the hive were recovered, recovered bees may not represent the total effect of glyphosate on treatment groups”, which completely guts everything in this paper! To me, this is an admission of guilt. They know they are going to be called out on the weakness of their experiment, and were probably hoping to hide behind this one line when confronted. 

The levels of glyphosate the bees in the study were exposed to (5 and 10 mg/L) is far too high, even for the supposed environmental levels they were trying to mimic (1.4 and 7.6 mg/L). The paper got these levels from other studies investigating glyphosate runoff into streams and waterways, which is not a fair representation of the concentration that bees will be exposed to. The paper also only fed the bees a sterile sucrose syrup, starving them of the amino acids normally available in their diet, which could have an effect on their gut bacteria. 

Finally, they never prove that a change in the composition of the bee gut microbiome would have any detrimental effect on the bee. In fact, we see from the bees sampled in the control group before reintroduction to the hive that there is already a very large natural variation in the gut biome. We also see that at all levels of glyphosate concentration, not a single bacteria was eradicated. 

Results from the paper ‘Glyphosate perturbs the gut microbiota of honey bees’

Despite the fact that this paper is fundamentally flawed to the point where a chemist with very little bio-training can rip it apart (I’m talking about myself BTW), the media have jumped on the story. Article after article now states, with some confidence, that scientists have found that glyphosate harms honey bees. This misinformation is already leaching into the real world. For example, here in the UK, Green MEPs Keith Taylor, Molly Scott Cato, and Jean Lambert have written a letter to Michael Gove (Secretary of State for Environment, Food and Rural Affairs) asking him to “urgently ban the use of glyphosate”. 

Green MEPs Keith Taylor, Molly Scott Cato, and Jean Lambert.

Why are they holding centrifuge tubes? Are they trying to convince us that they know anything about science? Because if they did, they would not be asking to ban glyphosate on the “findings” of this one paper. 

The decline of bees and other pollinating insects is a serious problem and one that is not solved by attacking a scapegoat. Yes, you may feel good about yourself, and you might get a few more people to vote for your political party, but the insect numbers will continue to decline. As I have previously said, glyphosate has been shown, time and time again, to have a very low toxicity to animals, and banning it would just force farmers to use other herbicides, which may potentially exacerbate the issue.

Glyphosate is often a target, not because people have legitimate concerns about its safety but because it is a backdoor into attacking GMOs. If you truly cared about pollinating insects, you would be furious with those who try to inject their own ideology and dislike of biotech into this discussion. You would be livid with a deceptive paper whose conclusion is not at all based on their findings. And you would demand strong, robust evidence before jumping to any conclusions.

About Myles Power (760 Articles)
Hello Internet! My name is Myles Power and I am a chemist from the North East of England, who loves to make videos trying to counter pseudoscience and debunk quackery in all of its various forms! From the hype around GMOs through to Atrazine turning the freakin’ frogs gay, I’ll try to cut through the nonsense that’s out there!

3 Comments on Glyphosate Is Not Harming Honey Bees Gut Microbiota

  1. Fascinating read, thank you!

    Liked by 2 people

  2. One fabricated study and heavily paid for by Monsanto, what a bunch of crap. There is a ton of studies proving that glyphosate kills everything in the ground, like bacteria, microorganisms, fungi that are responsible for producing nutrients for trees. Thats why trees and bushes are dying when area around them is repetitively sprayed.
    Go and have a glyphosate shake, it will make you feel much better.


    • There are many people who make similar claims for which they provide no evidence whatsoever, just like you did.

      Asserting someone is payed for by Monsanto won’t demonstrate that they are in fact payed by Monsanto. And demonstrating that someone is payed by Monsanto won’t prove them wrong. That’s what makes the shill gambit a fallacy.

      Plants like trees probably won’t die after you spray them with glyphosate because it….quote…”kills everything in the ground”. It probably is because glyphosate specifically targets one essential enzyme of most plants, including trees, which is what it is supposed to do as a herbicide. But, as far as I am aware of, nobody is spraying glyphosate around or on trees.

      Saying things like “If you think Glyphosate is safe, go ahead and drink it” will only make you look stupid, especially to the scientifically literate. It also shows that you lack the ability to have an honest conversation about this subject and listen to the opposition. Nobody is claiming that you can gulp roundup down as a milkshake, that’s stupid. The dose makes the poison, which means that there is always an amount where something is perfectly safe and an amount when it becomes toxic . The LD50 (lethal dose for half of the test subject) for glyphosate is a little less, but comparable to common table salt. And nobody is claiming you can drink a brine shake and be fine. Well, there is one crackpot on the internet, but don’t listen to her.


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  1. Glyphosate Is Not Harming Honey Bees Gut Microbiota | jtveg's Blog
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  3. No, a New Paper Does Not Show That Glyphosate Is Harming Honey Bees

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