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Transcript:
For the past decade, everyone has been concerned with the bees. What’s happening to them? Where are they going? What is the cause of colony collapse disorder? And day by day we get our answer: what’s wrong with the bees? Everything. Seriously, there are so many factors that influence bee populations that we can’t point to any one issue.
But one of the most popular problems to discuss is pesticides. Various pesticides tend to drive bees away or kill them in various ways, and it’s very complicated to figure out what exactly is happening and how we can stop it.
A new study is making headlines this week that claims to show that it’s not just pesticides that are the trouble, but also herbicides, and the bad guy is Monsanto. Monsanto, the bane of my skeptical existence, because they’re so often the target of pseudoscience and fear-mongering, while at the same time they’re an asshole corporation that does asshole things. It’s like if Trump were to ever say something that wasn’t an outright lie and it was my job to defend him on it. It’s gross but whatever, that’s my cross to bear.
Monsanto makes an herbicide known as glyphosate. Since it’s not a pesticide, it’s not meant to cause any harm to bees and insects. However, some researchers suspected that it might cause bees harm in another way — by affecting their gut bacteria. The researchers found that bees exposed to glyphosate were more likely to lack an enzyme in their guts that is targeted by the herbicide, which then in turn makes them more susceptible to diseases they may encounter later. So yeah, not good.
Is it time to panic and ban glyphosate, as people have been attempting to do for years, mostly because it’s produced by Monsanto and that’s scary, and so people assume it must cause cancer, even though scientists can’t find evidence to support that claim. But forget about the cancer, now it’s all about BEES!
So no, obviously it’s not time to panic. Here’s what you need to know: the study involved mega-dosing these bees directly with glyphosate for several days, without really establishing how much they’re likely to encounter in the wild. And strangely, bees who got 5mg of glyphosate had worse outcomes than those who got 10mg of it. The researchers aren’t sure why — maybe more of those bees died before they could be recaptured, or maybe the results for 5mg are a statistical blip. More research needs to be done.
Also, honey bees aren’t in trouble. This study only looked at honey bees, which are an invasive species here in the United States that is actually quite well protected, because they exist in large colonies that can protect individuals, and because they are protected by the humans who keep them. Native bees, however, aren’t so lucky. A lot of those bee species are lone wolves who don’t have a hive to help protect them, and they’re the ones who are doing the vast majority of the pollinating. Maybe glyphosate will affect them in the same way it affects honey bees, but we don’t know that. Again, we need more information. As of right now, it seems like the worst thing happening to bees is right in front of our faces: the loss of their native environment, which we destroy in order to have the prettiest lawns and the most convenient highway systems.
So when you see The Guardian breathlessly reporting that Monsanto is once again destroying the world, take it with a grain of delicious, genetically modified frankensalt.
Why did the researchers choose the exposure levels of 5 and 10 mg? Is it reasonable to assume that an individual honeybee could be exposed to those levels outside of the laboratory?
Those levels were chosen arbitrarily. They are close to levels that are actually sprayed on crops, not levels that would be likely to be found in the environment.
The PNAS study does not show that honey bees are harmed by glyphosate.
What they showed, is that the microbiome of bees eating pure sucrose solutions, or pure sucrose solutions containing 5 ppm glyphosate and 10 ppm glyphosate are subtly different. Are those differences important? Do those differences cause adverse effects? They have not shown that.
The levels of glyphosate they are using are extremely high. Bees would (essentially) need to feed directly off of glyphosate solutions being sprayed onto fields. There is no data showing that those levels are a ‘realistic’ exposure level.
Then they showed that when they tried to grow bacteria in 10 mM glyphosate (that is 1,690 ppm), in minimal media (media without aromatic amino acids), they observed disruption to bacteria growth (figure 4). Those levels would need direct contact with glyphosate being sprayed.
That is about 5,000 times higher than glyphosate levels actually found in honey in agricultural areas.
https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0198876&type=printable
The typical concentration of glyphosate that is sprayed on crops for suppression of weeds, is ~1.3 ounces of the 41% concentrate in a gallon of water (128 ounces). I calculate that to be about 25 mM/L or about 4,000 ppm.
https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5386499.xls
Bees would have to be drinking directly from the sprayers that are spraying the diluted glyphosate onto the crops to get 10 mM glyphosate. How realistic is that?
Even with those extremely high and unrealistic glyphosate levels, bacteria were not killed, they just grew slowly. Not surprising when they use media that doesn’t contain aromatic amino acids (the way the normal bee diet does). Is that slow growth problematic?
I find it interesting that they don’t cite this paper that looked at the effects of glyphosate in rat gut. Why not? It was out before the PNAS paper was submitted. I suspect because they are trying to generate a ‘narrative’ that glyphosate is bad for gut bacteria, and the (well done) paper on rat gut microbiomes shows that it isn’t.
https://www.sciencedirect.com/science/article/pii/S0269749117328099
They measured minimum inhibitory concentration of glyphosate, (in rich media, simulating actual gut contents) for 22 different bacteria, and found it to be between 5,000 ppm and 80,000 ppm. 5,000 ppm is higher than what is sprayed on fields to suppress weeds.
Well, there was his talk about Chinese mercantilism…
Anyway, yeah, I always end up saying “It’s not killing the bees, but I killed the wasps.” (I had a major wasp infestation earlier this year.)