Neonicotinoids: euphoria then death for bees


Two papers published in the journal Nature earlier this week are causing quite a stir in the bee world. The first, “Seed coating with a neonicotinoid insecticide negatively affects wild bees” by Rundlof et al. is unique in that the authors were able to perform controlled field experiments. This is often difficult to do because neonicotinoids are so prevalent in the environment that finding “clean” fields is tough.

But these scientists, working in Sweden, were able to obtain sixteen test plots of oilseed rape (canola). In eight of the plots, the canola seeds were treated with a combination of Clothianidin and a non-systemic pyrethroid. The other eight fields were planted without the insecticide treatment.

Not surprisingly, the wild bees in the treated fields were severely affected by the insecticides. What amazed the researchers was the amount of disruption. They found reduced wild bee density, reduced solitary bee nesting, reduced bumble bee colony growth, and reduced bumble bee reproduction. According to lead author Maj Rundlof, less than half as many wild bees were found in the treated fields, and colonies of bumble bees failed to increase in weight. Oddly, the honey bee colonies in the test appeared normal.

In the second study, “Bees prefer foods containing neonicotinoid pesticides” by Sébastien C. Kessler et al, researchers found that bumble bees and honey bees were unable to taste neonicotinoids but consistently chose syrup containing neonicotinoids over syrup that didn’t. Why? Some scientists believe that the effect of eating neonicotinoids may produce a euphoria in the bee similar to the effect of nicotine in humans.

So, given a choice of flowers—some with the insecticide and some without—bees may prefer the treated flowers because they get a high, even though that choice increases their overall exposure to the toxic chemicals and may cause impairment and death. Sound familiar?

In my opinion, these papers confirm what we bee-lovers have always suspected, which is that wild bees will be far more affected by field-applied pesticides than managed honey bees. Managed honey bees, after all, can be moved out of a field at the close of pollination season, whereas the wild bees cannot leave.

When compared to honey bees, most wild species:

  • Are active (and reproduce) during a short season, not much longer than the flowering time of a crop like oilseed rape
  • Fly only short distances and so are limited in their food choices
  • Live in the soil where the contaminants remain active for long periods
  • Have small populations sizes so the loss of a few individuals is significant

How important are these wild bees? How much pollination do they actually do? The answer, I think, is that we don’t really know. But having studied wild bees in graduate school, having spent years watching them, photographing them, and learning to identify them, I believe we underestimate their importance. I also think honey bees get a lot of credit for the work done by wild bees.

Determining their value is difficult because of their size. When we think of wild bees, we tend to think of the monsters: orchard mason bees, bumble bees, carpenter bees, even some of the diggers and miners. But many of the wild bees are so small that most people would never notice them. Some the size of fruit flies look like tiny splinters on a flower or a speck of dirt. Because they are so small and fast, it is hard to see what they are doing. It’s even hard to do controlled studies because they are difficult to screen out of a field or test plot.

But work? These little ones work themselves silly giving us flowers and trees, herbs, seeds, crops, medicinal plants and more.

If we studied only those living things that are easy to see—eliminating molds, viruses, bacteria, and single-celled plants and animal—we wouldn’t have a very good idea of how the world works. Similarly, if we study only the bees that are easy to see, we get a skewed view of how pollination works.

For example, I think a little sweat bee, Halictus rubicundus, may be one of North America’s premier pollinators. Found in all 50 states and most provinces, it seems to be everywhere, but no one has even bothered to give it a common name. When you walk through a field, they scatter like tiny flies, but work side-by-side with the recognized pollinators like honey bees and bumble bees.

Only after we eliminate them—along with the many other silent pollinators—will we know how valuable they were. When that happens, we will be sorry. We will wonder what was ever going on inside our maximum-crop-yield, perfect-produce, chemical-industry-protecting little brains. Of this, I am sure.



Halictus rubicundus are working hard all around us. This is a male on a chocolate mint. © Rusty Burlew.


  • That is a great post, Rusty. And I agree completely—we have so many species of insects that no one pays any attention to—yet if they die out, it will have far reaching consequences. Before I installed my new bee packages, I wasn’t seeing any honey bees on the fruit trees near my house—but it looks like they all pollinated quite well.

    My mantra lately has been that if mankind were to go extinct tomorrow, it would not be noticed at all (except for our domesticated animals), but if the bees all went extinct tomorrow, humanity would be in dire straights and probably on the brink of starvation within 5 years or less. Humbling…but true. We NEED the pollinators more than they need us!

  • Hallo Rusty Do you have a photograph of a honey bee and a sweat bee using the same scale to help me get a visual idea of how small the sweat bee is. Or perhaps a picture of a sweat bee on an easily recognisable flower like a Roberts geranium for instance. Thank you

    • Lindy Lou,

      That’s a good suggestion and I will see if I have anything. I may have to catch them and put them in a jar and then photograph, but I like your idea. Bear in mind the the term “sweat bee” encompasses an entire family, Halictidae, that contains about 2000 species with quite a large range in size. The one in my photo is about mid-range, I think.

    • That’s a fact. Just last weekend I was trying to convince my neighbor that he shouldn’t let his two elementary school children play around him while he’s spraying RoundUp on everything. His response? “It’s harmless. It just kills plants.”

    • Castor/Rusty,

      To be fair, and as you’ve pointed out before Rusty, the dose makes the poison. The IARC does not assess level of risk, but simply classifies a chemical on whether it can cause cancer without regard to dose. Group 2A lists a number of chemicals, but also includes high temperature frying and even disruption of circadian rhythms. In other words, glyphosate may pose a risk, but this study does little to tell us what that level of risk is. The preponderance of research elsewhere both industry funded and independent, tells us that risk is low even amongst workers exposed to glyphosate on a regular basis.

      Please don’t take me as a chem industry apologist, I’m as concerned as anyone on our over reliance on chemicals in agriculture. But I’m also a big fan of evidence and consideration of what that evidence can/can’t tell us.

      • Stephen,

        I appreciate your view. I am one of the few people on earth who studied herbicide science for a whole year in grad school. This makes me nowhere near an authority, but it does make me suspicious. Some of these compounds are nasty and often it’s not the original compound itself, but the metabolites that present the real problem. Generally, metabolites are not considered in toxicity studies, and neither are synergistic effects because there are just so many possibilities. Not only do you have synergism between the pesticides, but you also have synergism between the metabolites, and between metabolites and other pesticides.

        I agree we have no definitive studies on glyphosate, even though it’s been around for a long time. But there are strong economic and political pressures against finding anything wrong with it. We treat glyphosate the way we treated DDT in the old days, assuming it is as safe as spring water, but I think we will eventually find that to be wrong, like other things that are too good to be true.

        I’m a patient person. I’m willing to wait. It may be ten, twenty, thirty years from now, but I’m sure we will come to regret our carefree attitude about this formulation.

      • Stephen,
        I’ve worked in and around chemical process plant my whole life, hand in glove with the pharmacists, chemists and process engineers – I do the electronic control side of things. None of the people, right up to very senior level that I have ever worked with would act on anything other than “good” science. They try exceptionally hard to be ethical.
        But we are all beginning to understand that there are little understood and potentially far-reaching consequences of what we do, chemically. Some of it may be impossible to undo. The penny is beginning to drop.

  • Great article and thanks for sharing. Question, do the seeds produced by plants treated with Neonicotinoids carry the insecticide as well? There is volunteer canola in many of the hay fields and pastures in the south. It blooms in March offering an early pollen and nectar source and the bees work it heavily. I considered planting some but it is quite invasive in the hay fields so I decided not to plant. Not trying to lessen the intent of the article but a more troubling issue in my area is the use of herbicides (RoundUp, 2.4 D, Grazon) and I can find little or no information on them. Obviously herbicides eliminate habitat, but are there other negativities regarding associated with them? I am repulsed by all of them but GOOD accurate science like these studies (mentioned above) do a lot to help change the general public’s thinking. Again thank you for all of your efforts, I still hold to the phrase, as we know better, we tend to do better.

    • David,

      A tiny amount may be present in the seed of plants treated with neonics, but it is probably negligible, especially compared to background levels of these chemicals found in the soil and water. In some places in Europe, they have great difficulty in finding fields clean enough to do testing, so I’m sure the same is true here. In short, I wouldn’t worry about it: there’s not much you can do.

      As for your questions on herbicides, see the discussion in the above comments, especially from Castor and Stephen. Recall that 2,4-D was a component of Agent Orange.

  • Thanks for the article. You really hit the nail on head. A fantastic photo! I will try to be more observant of these wild bees in my gardens. Chris

  • Rusty,

    I do a lot of community outreach with honey bees, planting for pollinators, and pesticide awareness. I can’t even begin to describe to you many beekeepers tell me that they don’t think that these dubious systemic chemicals are problematic for bees. In fact these people, I’m biting my tongue to use other descriptive words for them, are against restricting usage, they feel I am a BS artist and shouldn’t be allowed to pedal my “garbage” about chemicals that have been found to be harmless to pollinators. I have collected 100s of signatures from ordinary folks who are completely behind eliminating these ubiquitous and dubious systemic chemicals in support of our Maryland Pollinator Protection Act.

    I just hope that sooner, and not later, more beekeepers get out into their communities and talk to their friends, neighbors, relatives, or even volunteer to handout information to the general public to make everyone aware that these systemic pesticides are dangerous and killing us all!!!

    Bill Castro

    • Bill,
      The collective human animal is notoriously slow to accommodate change – especially when big agro and government have been feeding them their side of the argument for a few generations now. Naive people find it really hard to accept and admit that they have been ‘had’.

      Keep on banging the drum and ensure that it is backed with good science – it’s the only way.

  • When will we learn – nature is the best and loudest voice for us to listen. When we ignore the result is human illness and disaster.

  • Can we sue Phillip Morris on behalf of the bees for the known damaging effects of nicotine? Just saying…

  • Been meaning to drop you a line about this…

    On the TV show “Elementary” there have been several mentions of neonics.

    The show is an update of Sherlock Holmes. In this version, Sherlock has a hive of bees on his roof.

    And there is supposed to be an episode next week revolving around bees. It airs on Thursdays, on CBS @ 9 Central time.

    I’m thinking it would be a good idea for bee folk to support this show. This type of mainstream attention to this problem will do more to raise awareness than hundreds of articles in scientific publications that most people will never see.

  • This is a video of one of my bees that I believe may have been exposed to a pesticide. The ENTIRE hive is doing this, with bees literally pouring out and dying on the ground. They were fine on Thursday, on Saturday am the death count was already at 500 bees or more. Drones and workers. Does this look like chemical or neonictonoids to you?

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