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Pesticides and Bees

March 28th, 2012 at Wed, 28th, 2012 at 4:18 pm by Karen Dale

In my interviews with Island beekeepers and their difficulty keeping honeybee colonies healthy, the Island’s use of garden chemicals came up often. “The Aisle of Death” was the much-repeated term for the shelves of stinky spray-cans and bags of pesticides, herbicides, bug dusts, and fertilizers.

Beekeeper Cheryl Grunbock told me that “bees are the most susceptible of insects: they’ll die way before you get rid of your target insects.” In picking up a can to kill those aphids, caterpillars, thrips, termites, or wasps in your fruit trees, roses, or around your foundation, you just might be killing the very insect that makes your fruit tree fruitful.

I looked at many of the garden products on our local shelves and found that many had the following chemicals that are highly toxic to honeybees. And there’s a market for them, as many people don’t want to take the time to diagnose, but just want a convenient Kill in a Can. So while there has been efforts to steer purchasers away from the most lethal, bee-killing, water polluting substances, you can’t really blame the local stores from carrying these products if Islanders are buying them.

It’s up to you the buyer to make a good decision. Toward that, I provide the following list of baddies, with a mnemonic device at the article’s bottom to help you remember them.

Carbaryl, malathion, neonicotinoids, and pyrethrins 

Carbaryl one of the USA’s most widely used pesticides used against insect pests. One of the most widely used is Sevin, which combines carbaryl and malathion to kill aphids, caterpillars, thrips, Japanese beetles, and other insects. The EPA has requested that the following be added to all Sevin packaging: “This product is highly toxic to bees exposed to direct treatment or residues on blooming crops or weeds. Do not apply this product or allow it to drift to blooming crops or weeds if bees are visiting the treatment area.” However, Bayer CropScience protests that it has a Sevin formulation, XLR Plus, that is a finer-grained dust not so likely by bees to be mistaken for pollen and brought back to the hive with killing effect, so it feels it can refuse the EPA’s request. 

This carbaryl-malathion combo is in a lot of the products I saw, such as Bonide Fruit Tree Spray that is already banned in California. Bonide puts out a lime-sulphur spray that’s less toxic, or you can use insecticide soaps or Bt as the green alternative.

Products with carbaryl or malathion on local shelves: Sevin, Bonide Fruit Tree Spray, Corry’s Slug-killer. Also beware it’s in Ortho Basic Solutions, Ortho Malathion Plus, and Orthos Mosquito-B-Gone Tree & Shrub spray. 

Systemic Neonicotinoids

These are systemic chemicals derived from nicotine that the plant takes up within. Bees get it when they (and other insects) suck on the water exuded by plants through their leaf edges (guttation), and the chemical can kill a bee within minutes. Such neonicotinoids as imidacloprid, clothianidin, or acetamiprid work on the nervous system, causing bees (and termites, the target bug for many products with this active agent) to get confused: they don’t collect pollen, and they lose their navigational powers and thus, their way back to the hive. 

Because these neonicotinoids are systemics, farmers have adopted them happily as an alternative to spraying. However, both through a dusty application process and through guttation, honeybees HAVE become exposed to these harmful chemicals.  After studies of colony collapse disorder found imidacloprid highly correlated to high levels of honeybee deaths, these chemicals have been banned in France and nearly so in Germany, and in the State of California their maker, Bayer CropScience, has quietly asked the state ag department to stop recommending its use to orchardists.

(After I posted this story, a friend sent me this link to an article about neonics and bees at Mother Jones:

Local products with neonicotinoids: Bayer Advanced Complete Insect Killer, Bayer Advanced 12 Month Tree & Shrub Protect & Feed, Ortho Tree & Shrub Insect Control. With Acetamiprid: Ortho Flower, Fruit & Vegetable Insect Killer and Ortho Rose & Flower Insect Killer.

Pyrethrin and her scary daughters

The first pyrethrins were developed in the 1800s and were once the most widely-used pesticides. They are the principal agents used against mosquitoes, especially in the malaria-prone countries, yet bugs are developing resistance and threatening our ability to ward off malaria. Pyrethrin works by paralyzing the nervous system: the insect’s nerves cannot relent firing signals, and so the insect becomes paralyzed and literally falls from the air. 

The original formulation of pyrethrin broke down by sunlight after onlly a couple days, so stronger, more toxic formulations have been developed that, while not toxic to humans, ARE to small bees. These 2nd-gen Pyrethrins are legion, but most end with “thrin”—deltamethrin, cypermethrin, permethrin, bifenthrin, and cyfluthrin.”

Products with pyrethins: Green Thumb products “Flying Insect Killer”, “Insect Control” and “Home Insect Killer. Lily Miller Multi-Purpose Insect Spray, some Safer products like “tomato & Vegetable Insect Killer and “Yard & Garden Insect Killer”, Bayer Advanced Lawn PowerForce Multi-Insect Killer, and Bonide Delta Eight Insect Control, plus many RAID products.

Here’s a mnemonic device to help you remember and spot the most toxic active agents in these garden products: “Neo burns carbs and gets thin at the Marathon.”  ”Neo” for neonicotinoids. “Burns” for “pyre” as in pyrethrins. “Carbs” as in carbaryl. “Gets thin” as in “thrin” as in those 2nd-gen pyrethrins. Marathon because it sounds a little like malathion.

Another helpful device may soon be showing up on garden product shelves. A local group is seeking to revive a 2006-07 program, Garden Green / Drink Clean that used hang-tags to educate buyers on the best-to-worst chemical products. Watch the Beachcomber in coming weeks for news of these useful and green program.





gardens on the south end of Vashon Island, on a sandy hilltop overlooking Quartermaster Harbor. "Garden On, Vashon" shares what the Island has to teach us about gardening HERE—from making soils to sowing seeds to raising plants to harvest, cooking, preserving, and designing new ways to cultivate your little chunk of Vashon Island. To contact me, email, or leave a comment.

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