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Imidacloprid: What You Must Know Now

Pesticide Implicated in Widespread Bee Deaths

While environmental activists including the SafeLawns Foundation claimed a temporary victory Wednesday, Sept. 16 in the emerging battle concerning the widespread use of imidacloprid in Worcester, Mass., beekeepers and many other observers across North America are deeply concerned about the precedents being set in the rural community.

As the threat of exotic invasive pests spreads— just as more alarming information becomes available about the pesticides currently in use — it is imperative correct decisions be made in situations for which no easy answers exist.

On Friday, Sept. 11, SafeLawns, the Toxics Action Center of Boston and later the Pesticide Action Network North America sent out an urgent call to block a proposal to spread more than 1 million gallons of imidacloprid solution into 15 square miles of soil in Greater Worcester, in the center of Massachusetts. Worcester has made national headlines due to its overwhelming infestation of an exotic invasive insect known as the Asian longhorn beetle. Approximately 25,000 trees have been cut down already and imidacloprid, synthetic nicotine, is the only known treatment for the pest.

Imidacloprid, marketed as Merit by the original manufacturer Bayer, is well documented for its toxicity to bees, as well as birds, worms and aquatic life. Many beekeepers, environmentalists and scientists — though not all — feel that imidacloprid is the root cause of colony collapse disorder (CCD) of bees. CCD is a mysterious ailment that began wiping out millions of beehives in the United States in 2006, just a year after imidacloprid replaced diazinon as the pesticide of choice for many insect infestations. Diazinon was banned by the EPA in 2004 due to its toxicity to birds and humans.

France has long-since banned most applications of imidacloprid ever since the synthetic nicotine compound was blamed for wiping out its bee-keeping industry during the 1990s. The Bayer Corporation reportedly paid French beekeepers $70 million to rebuild the beekeeping industry, but as recently as Sept. 15 a representative of Bayer claimed to the Boston Globe that imidacloprid has “no connection whatsoever” to colony collapse disorder. Widespread evidence and common sense suggest otherwise.

“Findings reveal a disparity between independent research and the research that was undertaken by Bayer,” said a September 2009 report by Buglife, a British conservation group that released the most comprehensive study ever published about imidacloprid.

The proposal considered Sept. 16 by the Massachusetts Pesticide Board subcommittee would have allowed the U.S. Department of Agriculture to use three times the legal amount of imidacloprid in soil treatments around Worcester starting in the spring of 2010. When beekeepers and others began contacting SafeLawns and asking for help, we rallied allies and voiced our collective opposition. At the end of the meeting, the subcommittee wisely asked to table the issue for two months to gather more information.

“I don’t believe that the environmental assessment done by (the EPA) is sufficient to justify any treatments because, as part of the assessment, they must determine if the bees will encounter enough imidacloprid to cause harm,” said Dean Stiglitz, a beekeeper from the Worcester area. “The problem is, no one has data showing how much imidacloprid will end up in the pollen, nectar, and/or plant resins (that bees collect) of the early blooming maple trees. Certainly not with the dosages (proposed).”

The Toxics Action Center, which organizes community support for pesticide reduction, drafted a letter, which was read aloud to the Pesticide Board. Here are just a few excerpts:

“Imidacloprid can persist in soil for 26.5 to 229 days in soil,” wrote TAC. “For this reason, direct application to soil as the U.S. Department of Agriculture is proposing should be avoided at all costs. It can easily migrate from soil into groundwater resources and has been detected in both ground and surface water in New York. California put imidacloprid on its groundwater protection list due to its potential to contaminate groundwater.

“Imidacloprid has been linked in animal studies to reproductive, mutagenic and neurotoxic effects. There is reason for concern about human exposures if it migrates into drinking water.”

The chemical, unfortunately, is the only known solution in the fight against the Asian longhorn beetle, which is believed to have first arrived in New York City in packing materials from China in the 1980s. Perhaps the most troubling insect ever to invade the U.S., it infests most deciduous hardwood trees with the exception of oak. By boring pea-sized holes into trees, the insect causes a slow but certain death.

Virtually everyone agrees that doing nothing is not an option, yet this is clearly a situation with no perfect solutions. Citizens of Worcester, justifiably, do not want to lose any more of their trees to the insect. The maple sugar industry of Northern New England is in a virtual panic that the insect will spread northward. Yet beekeepers are petrified about the pesticide impact on their hives — especially given that the pollen of maple trees is an essential spring source of food for the bees. Imidacloprid does wind up in the pollen of the flowers all most treated trees.

Given that imidacloprid is the only control, two primary application methods exist. One involves manually injecting trees with small amounts of imidacloprid. The other involves drilling vastly larger amounts of the pesticide six inches deep into the soil. While everyone agrees that injection is the preferred method, soil “drenching” has been proposed in Worcester due to cost considerations.

Christine Markham, director of the Asian Longhorned Beetle National Program for the USDA told the Boston Globe that soil injection is more “cost effective” than tree injection.

“We will be able to treat more trees,’’ said Markham.

Treating the trees is different than saving the trees, however. Scientific data collected at numerous infestation sites across the country shows that soil injection offers low efficacy in relation to tree injection. Injecting a tree has shown to be virtually 100 percent effective for up to two years; soil injections often need to be repeated year after year — which eventually mitigates any cost differential.

“Soil treatment, while the cheapest option, is like using a fire hose to treat for this beetle when really a small syringe would work just fine,” said Megan Jenny of the Toxics Action Center. “We should be phasing out toxic pesticides and replacing them with safer alternatives. In this case, the tree injection method may be significantly safer than soil applications. Tree injection minimizes the amount of pesticide needed, prevents the pesticide from migrating into groundwater and drinking water, and reduces pesticide exposures to the environment.”

Whether you live in Worcester and are affected by this immediate crisis, or you reside anywhere else in the nation, the imidacloprid issue affects you directly. By most estimates, honeybees are responsible for pollinating a third of our nation’s food supply. Any use of a pesticide that can harm the bees should be carefully considered — yet most homeowners who apply imidacloprid for grub control on their lawns or insect control on their fruit trees never even think about the impact on bees. Most people have never heard the word imidacloprid, which is buried in the fine print of the pesticide label.

With two months until the Pesticide Board in Massachusetts takes up the issue again, both sides will be preparing arguments. On the one hand, Bayer and the other manufacturers will continue to maintain their imidacloprid is safe and the USDA, faced with finding a solution to the Asian longhorn beetle, will push for widespread use of the pesticide. On the other hand, SafeLawns, Toxics Action Center, the Pesticide Action Network and others will point out the myriad toxicity issues associated with imidacloprid.

We urge all of you to: 1) Form an educated opinion and 2: Make your voice heard. If you live in Massachusetts, write to Gov. Deval Patrick and Senator John Kerry and all of your other local representatives. If these folks hear multiple voices on the same issue, they will respond. If you live anywhere else in the nation, keep your eyes out for issues involving honeybees, or imidacloprid, or pesticides in general.

At your own home, read those pesticide labels. Outside your home, eliminate or minimize pesticide use and never attempt to treat for the Asian longhorn beetle on your own; it is a job for a licensed professional. And within your larger community, don’t be afraid to speak out. Nothing less than our forests and our food supply depend on it.

About The Author

Paul Tukey

An international leader of the green movement, Mr. Tukey is a journalist, author, filmmaker, TV host, activist and award-winning public speaker, who is widely recognized as North America's leading advocate for landscape sustainability and toxic pesticide reduction strategies.

Number of Entries : 1023
  • Kai Connolly

    The shortage of bees in the southwest has been pronounced this last growing season. My yields were substantially reduced due to the lack of insect pollinators and we resorted to hand pollinating. It is worrisome in the short term and potentially diasterous for the future of our food supply. Each county should regulate and monitor pesticide use for the welfare of all. And companies like Bayer should be held culpable for resultant health issues that they ignore in pursuit of profit. We’ve been down this road before. It’s time we learned from our past mistakes because as we can see everyday, some injuries to the ecosystem are irreversible.

    • Paul Tukey

      I wish everyone felt this way. This is indeed a very dangerous path.

  • Linda Fortune

    Who said that Imidacloprid is the only pesticide that will kill the Asian longhorn beetle? And, has any one contacted the Chinese to see if such a beetle came from there? If it in fact did, what do they use to kill it? Just a friendly curious question, how is it that something so toxic as imidacloprid was developed to kill a beetle that only imidacloprid would kill…is this franken-side, or franken-Alb…I hope someone is awake and thinking out there? Don’t let them get away with it!

    • Paul Tukey

      The beetle did originate in China, where it has some natural predators. That is a big part of the problem with “exotic invasive” insects and plants that wind up here through travel and commerce. They establish themselves, but have no natural predators to keep them in check. They reproduce or grow out of control. Imidacloprid is the only available application for the beetle, but I know scientists who are working on alternative controls as well.

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  • Jimmy

    You may find this interesting. I am a Branch Manager for probably the largest fertilizer/pesticide dealer in the USA. I brought up the question about imidicloprid vs. bees to a Bayer (the manufacturer) rep. His reaction was quite shocking. He says don’t apply Merit (trade name for imidacloprid) around bees. He was absolutely amazed when I stared him in the eyes and reminded him that Merit is systemic in its mode of action and that the bee’s life revolves around collecting pollen. His response was that Bayer would look into this idea.

    • Paul Tukey

      I’m not surprised. One-on-one like that, you’ll get the truth that you won’t hear elsewhere. Thanks.

  • Allison

    Besides the beetle, I thought imidacloprid was recommended for adelgids, which seemed reasonably safe, because I don’t think of hemlocks having flowers that attract bees. Maybe I’m way off base?

  • EC

    Check the facts. Imidacloprid has now been found to not be the cause of the bee colony collapse. The current reason is a virus transported
    be bees brought into the USA. Please check this out. The easiest thing is just blame the pesticides without conclusive proof

  • Scott Reil

    EC, you need to check who’s checking the facts…

    The EPA’s primary recognized and funded studies on CCD are happening at Penn State. Penn State has been presented with many millons of dollars from Bayer (American headquarters in Pitssburgh, where 148 of just over two hundred Bayer Ag employees are Nittany Lions), with nearly two million directly given to the Agriculture programs. Bayer also bankrolled the rebuild of the Pesticide Research Lab at Pen State, which interestingly has been renamed the Chemical Ecology Lab. And the studies there continue to focus on the 50 PPB range and higher, a range detectable and avoided by bees. EU studies find bee injury and mortality have been found to start and culminate in the 2-6 PPB range, a fact convenient to Bayer, and continually misleading in it’s “studies”. And these are exactly the levels we expect to see after several years of degradation of this product. And as ALL plant life uptakes this chemical, concentrating it to flowering points (hence pollen), any pollen gathering insect can expect a nearly continual exposure ass this stuff is introduced and reintroduced by wave after wave of plants (so even hemlock application will eventually move it to the bees perview, and yes, Paul, this is a very commonly used pesticide for wooly adlegid).

    Until sub-lethal testing is actually performed, one cannot rule out chronic neonicotinoid poisoning as a component of CCD. And considering that no actual EPA-mandated, required-by-law study has ever been performed, I am completely at a loss to see how EC determined neonicotinoids having been ruled out. Imidicloprid has operated under nearly 200 Section 18 emergency waivers since it’s introduction around 1997, despite the fact that Section 18 specifically states that such exemptions are to last “1) Specific or public health exemptions: no longer than one year 2) Quarantine exemptions: no longer than three years.” It is also interesting to note that any facts pointing to secondary poisoning or other environmental factor should immediately suspend a Section 18 waiver, hence the need for Bayer et al to squash any sign that there might be a connection. Also interesting in this regard is the EPA’s now seven year long refusal to honor an FOI request submitted by the NRDC

    So we have a lab virtually built (and almost certainly named) by the manufacturer of said toxin, to study the effects of said best selling product, one on which said company has clearly bet the farm, and now said lab is returning a clean bill of health. What a surprise. Yet the EU finded studies, actually working with sub-lethal dosing found that Bayer outright lied on initial claims (saying it would never reach nectar or pollen despite no real supporting evidence, and that 5 PPM was the bee-lethal dose, despite the fact that it is 100 times more lethal than that) and that after 416 days of fallow conditions, 56% of the product was still viable in the soil and uptaken in a new crop. Perhaps most damning would be the company’s own text on a bag of their IMD product for termites “they stop feeding and are unable to maintain their colony.” and “This product makes termites susceptible to to infection by naturally occurring organisms.”

    Perhaps we cannot yet clearly point to IMD as the single causal agent in CCD, but there is ample evidence to support it’s destabilizing effect on bee colonies. On this alone we have sufficient and legally binding cause to suspend Section 18 exemmption and subject all neonicotinoid pesticides to tha actual reviews demanded by our laws. As to why these are not already being enforced as enacted is another troubling conversation for another day, but IMD is clearly tied into CCD and should be disposed of on that alone…

    • Paul Tukey

      Great email. Thanks for the clarification on the adelgid issue with imidacloprid. Since I gave up my own pesticide applicator license 14 years ago, or so, I don’t do a good job of keeping up with what chemicals are being used to kill whatever pest.

    • John Sawyer

      I agree with what you’re saying, but it needs to be taken one step further. I’ve been following this issue ever since Paul told us about the imidacloprid and bee connection a couple of years ago. Then 60 Minutes did a piece on it, which also mentioned the connection. I’ve talked to bee keepers and some scientists and I’ve read all the reports. At this point anyone who suggests there IS NOT a connection between colony collapse and imidacloprid either a) has their head up their ass or b) has a financial connection to a chemical company. Let’s be real.

  • Joseph J. Rosati

    Obviously, we are fighting a losing battle. Every applicator knows what immidacloprid does to bees. Ask anyone in the industry what is the best pesticide to kill bees. Imidacloprid and Fipronil are the most deadly pesticides ever used for bees. They are persistent; up to one year. If one bee touches a plant with either of these pesticides on it, they will kill an entire colony in days. Virus on you…

    • Slappy

      “yet most homeowners who apply imidacloprid for grub control on their lawns or insect control on their fruit trees never even think about the impact on bees. Most people have never heard the word imidacloprid, which is buried in the fine print of the pesticide label.”

      While the active ingredient is NOT buried in the fine print of the product label, the reason for this quote was about the homeowner. In many cases, the homeowner is the reason for a product to become “restricted use” or to be banned completely. The old adage “more is good” comes to mind. In addition, anyone who apples this type of a systemic to a fruit tree is nuts. Afterall, it is a systemic product that attaches to the carbon cell to translocate through the plant. A quicker contact product or horticultural oil will suffice for most fruit tree pests.

      Unfortunately, homeowners should never have access to most of the pesticide products on the market. Only a certified applicator should use these products. Trust me , I am an arborist and I have seen the devestation from ALB and from emerald ash borer as well as the haphazard use of pesticides by non-certified applicators.

      • Paul Tukey

        Great comment, Slappy. Couldn’t agree more.

        • Micheline L.

          Hi Paul we met in Hudson. I stumbled upon this post on imidacloprid and had to respond. I’m an agronomist and biologist and my business (Solution Alternatives Environnement) is fighting quite a battle in Québec to prevent (I write pesticide bylawns for cities wanting to ban pesticides and there are over 125 municipalities in Quebec banning pesticides) the use of imidaclorpid. Great info in the post but one info missing. In Canada there has been a emergency registration since 2008 for neem extract (injection) as control of emerald ash borer. Imidaclorpid/Merit is not even registered for this use in Canada. But Neem being a systemic is quite effective. Great research done by the Canadian Forest Service’s (CFS) and Bioforest technologies who designed a special injection system for neem. You can find great info from this website:

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