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Neonicotinoids Barely Found in Pollen of Seed-treated Plants

By Richard Levine

Neonicotinoids (or neonics for short) are a class of pesticide that has been popular with corn, cotton, canola, and soybean farmers for years. Instead of spraying pesticides on plants growing in the field, seeds are treated with neonics before planting. As the crops grow, the pesticide is taken up by the plants, protecting them from insect damage.

Richard Levine

However, this has been controversial in some areas because of possible damage to beneficial insects such as honey bees. In Europe, for example, three neonicotinoid pesticides have been banned for two years as officials examine the scientific studies on their effects.

Now new research from entomologists in the southeastern U.S. shows that neonics may not be as harmful to bees as they are being portrayed in the media because they are not being expressed in plant pollen or reproductive parts at levels that are high enough to hurt the bees — if at all — as this video with Dr. Gus Lorenz, an extension entomologist with the University of Arkansas, explains:

“When we look at the literature and the Internet, what it says is that neonicotinoids applied as seed treatments are then taken up into the plant and expressed in the pollen and in the nectar,” said Dr. Lorenz. “Well, that’s not so much what we found.”

When the researchers tested corn, one neonic was not found at all in the pollen; two others were found, but at extremely low levels, with the highest having a mean of 2.3 parts per billion. To put that into perspective, one part per billion equals one second in 32 years.

When they tested soybean flowers and cotton nectar, they found no traces at all.

“It’s not being expressed in the reproductive parts of the plants,” said Dr. Lorenz.

Read more at:

New research indicates neonicotinoids not showing up in plant pollen

USDA Report on the National Stakeholders Conference on Honey Bee Health

Federal Report Points to Many Causes In Dramatic Bee Disappearance

Richard Levine is Communications Program Manager at the Entomological Society of America and editor of the Entomology Today Blog.


    • Pat – honeybees only live for six to eight weeks during the nectar gathering season. Accumulation can’t happen under those conditions.

    • Sublethal doses may have an effect. However science has not been able to give evidence of sublethal doses causing any problems. A ban on neonicotinoids could cause substantial reductions in crop yields driving up food prices and causing food shortages. Until science identifies neonicotinoids as a cause of colony collapse which risk would you like to take.

    • There is ampule evidence of neonicotinoids being present in trace amounts in plants. That does not seem to be in dispute. However there is no scientific evidence of it being a cause for colony collapse disorder. It is interesting to read comments about “Studies out of Canada also show that in crop areas where neonicotinoids are used, that the surrounding wetlands are significantly contaminated with neonicotinoids.” What I find interesting is that Canadian bee colonies have been largely unaffected.

    • actually no, not in this instance, neonics
      breakdown even with just the humidity in the air, , they don’t accumulate

  1. Note that the only plants tested are corn, soy and cotton – very low on flower and pollen abundance. Bees find very little to forage anyways on these crops. The experiment was designed to yield the “no significant trace result. Studies on more abundant flower and pollen producing plants are likely to produce different results.

    • I agree that corn is not a big bee plant. But soybeans sure are, as are all legumes. Not sure about cotton.

  2. What has been found though, is that when farmers plant these seeds, neonicotinoids is found in significant quantities in the dust blowing off planting machines. This contaminated dust is then spreading out of the fields. Studies out of Canada also show that in crop areas where neonicotinoids are used, that the surrounding wetlands are significantly contaminated with neonicotinoids.

  3. Have scientists tested the pollen of surrounding flowering plants (versus only the commercial crop) that may take up the neonicotinoids and may have more expressed in pollen?

  4. Neonics are not the worst of pesticides. They have low toxicity to mammals. The problem is the prophylactic application to seeds of a persistent water soluble poison without regard to any known pest problem. With regards to how they work, it should be noted that they disable the immune system of insects which then succumb to viral or bacterial pathogens. This is what has been happening to honeybees and native pollinators.

  5. I am a beekeeper and the reason little pollen with neonics was found is because the neonics cause the bees to have memory loss and they cannot find their way home. Bees die in the fields unable to find home-soon we humans will not be able to find our way home. This is forced dementia on the human race.

      • Purdue actually did find levels in pollen irrespective of the crop. What is also misleading in this article is they do not provide the LD50 dose (the amount that kills 50% that consume that dose) for bees this is around 10 Parts per Billion. The article’s correlation between seconds and years is a red herring and means nothing. It is an attempt to make people think it is a small number so it must be too small to cause problems.

        The argument should rather be at what level there is no observable effect on the bees. Essentially how much can their bodies process without being affected. That has not been established in a controlled manner. It is ASSUMED that is 4 PPB or less. However this varies based on the bee species. Bumble bees show effects as low as .1 PPB.

        There are many different formulations of neonic insecticides. Some are applied as a foliar spray, soil drench, via irrigation water, via transplant water, seed coating, etc.

        Timing of application also plays a big part in exposure for bees. Seed applied coatings are the “safest” method when we are assuming the bee will be visiting the flower for the pollen/nectar. Plants naturally process neo-nics as they age. There is very little left in the plant to be exuded in the pollen/nectar when applied as a seed coating. Tests at Purdue showed less than .5 ppb for Farmore (which is the most widely used seed coating). Other application methods and timing produced MUCH higher results in pollen/nectar.

        As to the talc, this is NOT added by companies treating the seeds. It is added by the farmers to the seed hopper. Why? The seed coating is sticky in many instances. The talc is used to prevent sticking between the seeds. Many farmers no longer use talc and now use graphite. Graphite is cheaper and is much slipperier. It probably does not help with coatings being exhausted into the air.

        Modern seed planters use a vacuum pump to draw seeds onto a plate. The plate has holes on it where air is “sucked” through. This draws seeds over the holes and holds them in place. The plate turns and at the very bottom of it’s rotation the vacuum is removed from the hole, a brush knocks the seed off and it falls into a tube down to the ground where it is planted. Vacuum seeders are VERY accurate. They don’t easily get jammed. They allow a farmer to plant an acre of seed with an accuracy of within 100 seeds. This is a fantastic feat considering there are tens to 100’s of thousands of seeds planted per acre depending on the crop.

        Older “plate” seeders, like the John Deer 7000 series, do not use vacuum. The rely on a rotating cup or plate to pickup a seed from the seed bin and then transport it to the planting tube. Because seeds might not be uniform in size, sometimes two seeds are planted at once (too small of seed) or there is a skip (seed to large or odd shape). This means plate seeders are not as accurate. Farmers trying to increase yields must maximize the amount of seeds planted without there being too many. Too many seeds means not enough room for each plant and reduced yields due to lack of fertilizer, water and light.

        The benefit to plate seeders is none of the seed coating escapes into the environment. It is 100% contained in the seed bin and tubes. The seeds are immediately covered as soon as they hit the ground. Unfortunately most farmers have moved to vacuum seeders due to their increased accuracy.

        Installing HEPA filters on seeders may be an option, but I would not want to change them once they were filled with seed coating chips and dust.

        Companies are trying to improve the coating process to reduce stickiness, improve adherence to the seed itself (so the coating does not come off as easily) and reduce the need for buffers like talc and graphite.

        Sorry for the long post, but most people only have a little knowledge of the big picture. Most are not farmers, most don’t think about all aspects of production, etc.

  6. Great post Matt, very informative. I for one am trying to stay away from neonics, but it can be tough to do. Unfortunately I live downtown in Atlanta and for many of my neighbors buying at a big box nursery/retailers is the easiest route, and with my small lot my bee’s go off my property to forage. I’ve checked with all the retailers and they all use them at some point in the plants life. I try to start most of my annual flowers by non treated seed and try to mostly stick with perennials, I try to divide my plants when possible, or to start plants from cuttings, and to give some away to neighbors to grow. I lost my bee’s last year, they gradually just stopped coming home, not a lot of dead bees at home and no evidence of swarming. Had a full healthy hive up until September, so starting over again this spring.

    • Not entirely great. Right at the beginning Matt wrote, “LD50 dose… for bees this is around 10 Parts per Billion.”

      That’s nonsense. It’s akin to saying alcoholic beverages will make you drunk if they contain xx%.alcohol. Actually, it’s the total amount of alcohol you consume which determines how drunk you get, not the strength of the brew.

      The “D” in “LD50” stands for “dose.” It is a total quantity, not a percentage or ppm/ppb number. LD50 doses for pesticides vs. bees are expressed in units like nanograms per bee, not parts per billion.

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