What is a neonicotinoid?

oleander aphids

Neonicotinoids are especially effective against sap-feeding insects like aphids.

Neonicotinoids are a new class of insecticides chemically related to nicotine. The name literally means “new nicotine-like insecticides”.  Like nicotine, the neonicotinoids act on certain kinds of receptors in the nerve synapse.  They are much more toxic to invertebrates, like insects, than they are to mammals, birds and other higher organisms.

One thing that has made neonicotinoid insecticides popular in pest control is their water solubility, which allows them to be applied to soil and be taken up by plants.  Soil insecticide applications reduce the risks for insecticide drift from the target site, and for at least some beneficial insects on plants.

There are several different kinds of neonicotinoid insecticides.  The first neonicotinoid to reach the market was imidacloprid, a common ingredient in Bayer Advanced Garden insecticides.  This product can be sprayed on the plant, but is often more effective (especially on sucking insects) when applied to the soil.  Dinotefuran (Safari) is another, more highly water-soluble, neonicotinoid that is especially good on sap-feeding insects.

To find out whether an insecticide you see on the shelf of your hardware, pest control supply or garden center is a neonicotinoid, look on the list of active ingredients. If you see one of the following names listed, the insecticide includes a neonicotinoid:

  • Acetamiprid
  • Clothianidin
  • Dinotefuran
  • Imidacloprid
  • Nitenpyram
  • Thiocloprid
  • Thiamethoxam

In addition to being effective against sap-feeding pests, neonicotinoids provide good control against certain beetles (like white grub larvae in lawns), fleas (Advantage flea control products, and nitenpyram pills for pets), certain wood boring pests, flies (fly baits), cockroaches and others.

Environmental concerns

Initially neonicotinoids were praised for their low-toxicity to many beneficial insects, including bees; however recently this claim has come into question. New research points to potential toxicity to bees and other beneficial insects through low level contamination of nectar and pollen with neonicotinoid insecticides used in agriculture. Although these low level exposures do not normally kill bees directly, they may impact some bees’ ability to foraging for nectar, learn and remember where flowers are located, and possibly impair their ability to find their way home to the nest or hive. Despite the controlled studies completed to date, the actual impact of neonicotinoid insecticides on honey bees in the field are difficult to measure.  It is still not known whether these effects explain bee colony collapse disorder, or have had any effect in agriculture or, especially, in urban areas.

The relative infrequency with which bees are expected to encounter neonicotinoid insecticides in urban landscapes suggest that the impact of these insecticides in backyard gardens, when used appropriately, is probably minor.  To keep risk to bees and other beneficials low, however, a few simple steps should be taken: (1) follow the label directions carefully, (2) restrict neonicotine applications to the soil, or during times when bees are not foraging (e.g., in the evening), and (3) treat only those individual plants which need treatment for a known pest infestation.

16 Responses to What is a neonicotinoid?

  1. Kathy Cummings says:

    Following the Precautionary Principle, it’s wiser for us to stop giving neonicotinoids to bees now than waiting for them to disappear. Better safe than sorry!

    The above link was two years ago. What are we waiting for?

    • m-merchant says:

      The Precautionary Principle is based on the belief that any use of an insecticide should be avoided without airtight evidence that it is 100% safe. The problem with that principle is that 100% certainty safety is impossible to prove–ever. It also ignores the fact that there are benefits to using some insecticides, and that most environmental rules and decisions have always been based on balancing benefits vs. risks. If there were no benefits to humans of using these insecticides, we wouldn’t be having this conversation. But there are, so we proceed on the best available science to make decisions about what the risks and benefits are. BTW, in the U.S. over the past two years, the science on the safety of neonicotinoids has been equivocal. New studies have shown that bees may be more sensitive to neonics than we previously thought; but an increasing number of studies are showing that the bee problem known as CCD is most likely being caused by several factors other than insecticides. No studies have yet confirmed that use of neonictinoids per label directions are causing harm to pollinator populations. If you interested in reading more about this important and controversial topic, click here.

      • James says:

        ‘The Precautionary Principle is based on the belief that any use of an insecticide should be avoided without airtight evidence that it is 100% safe” This is not exactly correct, if it were true there wouldn’t be any pesticide use in the EU, but there is. The precautionary principle states that if a substance is suspected of causing harm its use must be stopped until proven otherwise. The key word is suspect. Everyone knows that 100% safe is not possible.

        • m-merchant says:

          I believe my description of the PP is reasonably accurate. It’s common to hear people or groups in the news who are concerned about a chemical agent, or new drug, or nuclear power plant to call for proof that the offending technology is 100% safe. You are correct in saying that knowing with 100% percent certainty that something is safe is not possible. However, suspicion is not a very useful criterion either. If we eliminated all drugs or pesticides or new technology that people were suspicious of for any reason, we would not have any technology. The important thing is weighing risks, which the EPA is fairly good at (though admittedly, not perfect) when it decides whether a product should be registered.

  2. Marianna Smith says:

    “restrict neonicotine applications to the soil, or during times when bees are not foraging (e.g., in the evening)” how is this going to help prevent the bees from ingesting the neonicotine? It disappears in less then half a day?

    • m-merchant says:

      Good question! Neonicotinoids do not disappear from inside a treated plant that quickly–you are correct. However, generally once insecticides dry, and are exposed to the degrading effects of sunlight, they tend not to be highly toxic to foraging pollinators. Many factors are involved in this including the absorption of insecticides into plant tissue, adherence of the insecticides to the plant, and the likelihood of the pollinator staying on a treated plant long enough to pick up a biologically significant dose. As far as neonics inside the plant harming a pollinator, most neonics are xylem transmitted, and tend to end up in leaves and stem tissue, with very low amounts in pollen and even less in nectar. These low amounts are presumed to not be harmful to bees, and are much less likely to cause harm than wet (or dry) leaf deposits.

      • JHobin says:

        I understand that sunlight helps to wash away these neonics, but once they get into the soil, don’t they stay, get reabsorbed by the plants, and become harmful to all sorts of pollinators? Neonicotinoids are definitely not harmless. I mean, is there even such a thing?

        • m-merchant says:

          Neonicotinoids, like all pesticides, are degraded by sunlight and microbes and other factors in the environment. They also stick, to varying degrees, to plant surfaces and soil particles, etc. Because of their water solubility, some foliar-applied neonicotinoids may be washed off plants and get into the soil, but these amounts will be relatively low. Even when soil applied, and absorbed into the plants as most neonics are designed to do, the amount that ends up in pollen or nectar is very low. That’s because most neonics are primarily xylem transported (xylem sap is the upward flowing sap in a plant and does not make up a significant component of nectar). As with all pesticides there are trade offs in their use (think of potential side effects as with most pharmaceuticals in medicine). Ultimately the EPA, which registers insecticides for use in the US, has decided that the pest control benefits of using neonics outweigh what is known of their risk. The EPA continually reevaluates the scientific data and should it decide that the environmental impacts of label uses of these pesticides pose unreasonable risks to the ecosystem, the permitted uses will change. This has been the policy with other insecticides (that are also toxic to honey bees and other pollinators), and this science based approach has worked well for many years.

  3. Brad1 says:

    A newly published Harvard study of neonicitonoid insecticide impacts on bee colonies reveal a direct link between the substances and colony collapse disorder. CCD rates in the US and United Kingdom, where neonicitonoids are permitted are much higher than in the European Union, where they are not. While it’s true that many factors may be at play in the CCD phenomena, it’s clear that neonicitonoids play a role. Many of the other factors cannot be controlled by the average home gardener. This one can. By not using Bayer Advanced garden insect control products, for instance, and other products containing neonicitonoids, home gardeners can help improve a very dire situation for honey bees. This is especially true in urban and suburban areas where there is no agricultural application of these dangerous substances.

    • m-merchant says:

      Brad, thanks for your comments. The new study you cite is by Dr. Chengsheng Lu and some beekeeping colleagues from Massachusetts. This paper and a previous paper published by this group have come under strong criticism today for their methodology, and for the high rates used, ostensibly, to prove that CCD is caused by neonicotinoids. Ignoring the fact that even a carefully dosed study with neonicotinoids could do no more than provide circumstantial evidence of a relationship between these insecticides and CCD, the doses used here appear to be much higher than would be expected in nature (135.8 parts per billion in sucrose water). A methodology paper Lu co-wrote with other colleagues in 2013 found very low rates of neonics in pollen (2.2 ppb) from Massachusetts bee hives, much lower than was fed here. Given all of this, I don’t find the new Harvard study compelling.

      Regarding your statement that home gardeners’ choice of insecticides can help improve a dire situation for honey bees, I could only agree with you if there was compelling evidence that neonics are the cause of CCD, which there is not. If there is valid concern, it would most likely be in agricultural environments where hundreds or thousands of acres might be planted with the same treated seed. This is the underlying assumption of all the studies to date: namely, that colonies would be feeding exclusively on insecticide treated crops with significant levels of neonicotinoids in nectar. In my experience, relatively few urban landscape plants are treated with these insecticides. Those that are, include occasional trees (highly valuable plants for whom treatment may be essential to kill borers) and the occasional ornamental or vegetable plant (or planting) with a specific pest problem. Any bee colony foraging in typical urban landscapes would be expected to visit treated plants relatively infrequently (pessimistically, for the sake of argument, say, one in a dozen of the plantings being visited at any point in time). It’s unlikely, based on what we know today, that such low doses would make a significant impact on bee colonies.

      I appreciate the suggestion that we need to reduce insecticide risks to bees, and will join you in urging gardeners to avoid spraying or treating blooming plants with any insecticide. I also would argue that these products should only be used when needed, and not in a mindless, preventive way. But making the leap to say that by boycotting the use of these products we will save the bees is not a statement that I’m willing to endorse at this time.

  4. John Dobbins says:

    M-Merchant please watch this TED Presentation on the neonic issue. The researcher speaking is Maria Spivak. Are you familiar with her work? She certainly would seem to have done her homework…
    http://www.ted.com/talks/marla_spivak_why_bees_are_disappearing
    I look forward to you views and comments about what she has to say.

    • m-merchant says:

      John, thanks for pointing out this TED talk. I have not heard of Maria Spivak, but I’m no bee expert either. If I were, I’m sure I would know of her as a University of Minnesota faculty member. She is obviously a good speaker and excellent advocate for pollinators. She also does a nice job of outlining all the pressures on bee health, her main professional concern. She also outlined the ways that pesticides can theoretically affect bees and bee behavior. My main beef is that she did not present some of the nuances about the issues surrounding the pesticide component of the CCD issue.

      Yes, there are numerous pesticides in bee pollen–including several pesticides put there deliberately by beekeepers to help kill varroa and tracheal mites, hive beetles and other bee nest parasites. The operative word is that there are “detectable” residues. Detectable, however, does not necessarily mean biologically significant. Our ability to detect pesticides at extremely low levels is very good with today’s analytical equipment. So good that we can detect levels far below those levels which might affect bee health. By leaving the discussion at detectability, she implies that any pesticides found in pollen must be bad for bee (and by implication, human health). This is not true. Beekeepers have been using insecticides in their hives to manage parasites for many years, with mostly negligible health effects on bees. And neonicotinoids have been in pretty wide agricultural use since the mid 1990s–CCD was first noted in 2006. EPA just completed re-registration of these products and concluded that they could be used safely for the environment when label directions were followed. Furthermore, in 2012, the year before Dr. Spivak’s talk, all the top CCD experts in the US got together and agreed that they could find no consistent connection between neonicotinoid concentrations in bee pollen or bee bodies and CCD. She didn’t mention that.

      With respect to neonicotinoids, these insecticides have been shown to be toxic to bees at lower levels than was previously believed. But most neonicotinoids that are applied to plants do not generally cross the plant/flower barrier. A tiny amount may in some plants, and the main battle between pro- and anti-pesticide forces at the moment revolves around how much. These sorts of discussions are crucial, but–lets face it–they are boring to most people who don’t appreciate the significance of the quantitative aspect of pesticide science.

      Dr. Spivak did not go so far to say that farmers shouldn’t be using these insecticides. She’s probably too good a scientist to do that. As a bee expert, she is also less likely to have a stake in the economic returns associated with pesticide use. In an ideal world we wouldn’t want to use pesticides. But pests don’t make for an ideal world. And pesticides do serve a valuable, and economically significant purpose. So it would and should come down to weighing costs and benefits of pesticide use.

      I support Dr. Spivak’s recommendation that we need more nectar sources in urban areas. I do not agree, however, with her advice that people should avoid using any pesticides around their homes as a way to save the bees. The amounts of legitimate urban use of neonics is relatively low, and to my knowledge there is no evidence that urban use of these insecticides is having a significant impact on managed bee hive health in the US. In fact, most (not all) managed hives are not placed in urban areas. They are more commonly used in agricultural fields and rural landscapes. And, based on annual phone calls I receive, I see no evidence of a decline in feral bee colonies in the Dallas area–the bees that you are most likely to see in your backyard. If a neonic was the best insecticide to protect a 50 year old shade tree in my back yard from a disfiguring or lethal pest, I would not hesitate to use it. I would, however, take pains to make sure it was a tree that was not pollinated by bees or else not in the flowering stage at time of the application.

  5. KarenH says:

    The current study on neonicotinoids(I am going to use abbreviation NNC) vs CCD rates apparently showed a correlation between the two, which suggests a relationship, no?

    Re amounts of NNC – you say that the amounts found in nature are much lower than those in the study. I think you need to add the qualifier ‘amounts CURRENTLY found in nature’. And then ask the question what will happen to those amounts if large scale use of this ‘safe’ pesticide is allowed? …Perhaps we should look to our European counterparts who do still seem to understand the old Hippocrates oath that one should ‘first do no harm’ in deciding what we do and do not allow in our environment. As with DDT, history has shown that by the time we figure out WITH CERTAINTY that a new chemical is harmful, it may be too late….

  6. Grace Cockburn says:

    Re: “The relative infrequency with which bees are expected to encounter neonicotinoid insecticides in urban landscapes suggest that the impact of these insecticides in backyard gardens, when used appropriately, is probably minor.”

    I disagree. I think the authors did not account for the fact that more and more ornamental plants are being produced by relatively few, ultra-large suppliers, and that virtually all of these growers are using neonicotinoids either as a plant spray or a soil drench. This spring, I have been asking at local garden centres before buying bedding plants, and have been emailing the larger suppliers directly. They ALL use them, on some if not all of their plants. If virtually every petunia, geranium, alyssum, snapdragon and other common bedding and hanging basket plant has been so treated, I’d say exposure of bees to this group of pesticides is almost guaranteed.

  7. jonny salmon says:

    Thank you, m-merchant, for your thoughtful commentary. Seems to me that an urban neonicotinoid incident with significant, i.e. newsworthy, fatality of pollinators is about as common as significant incidents of E. Coli in the hamburger supply. I particularly appreciate your discussion of the vast sensitivity of analytical equipment to detect in the parts per trillion range when bee toxicity is in the parts per billion range–a thousand fold difference. I do think concerned citizens should become conversant in these quantities. I would also like to see emphasized that the advent of selective pesticides (like neonics) has replaced broad spectrum pesticides (like OPs) and increasing use of IPM (integrated pest management) that balances natural enemies, cultural practices, and chemicals to achieve pest control, has dramatically changed the world of pest control. Today compared to twenty years ago, numbers of sprays in well managed landscapes has dropped by about a factor of 5 to 10, and the overall environmental and human risks (of bad thing) have also dropped to levels mostly not posing a concern. We are not living the time of lead paint, lead enriched gasoline, or broad spectrum highly toxics chemicals (OPs, carbamates, OCs, and so on). I am not a shill for the chemical industry, but neither can I afford to pay for organic food that costs way too much.

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