Skip to content

New Publication on Preventing Pesticide Poisonings in Bees

October 25, 2013

In the wake of the pesticide poisoning of 50,000 bumblebees, The Pacific Northwest Extension Service has just published a revised edition of a pamphlet with information on protecting honeybees and wild bees from pesticide poisonings.

As we see from the excerpt below, there are a number of other ways bees can be poisoned by pesticides besides the obvious way of ingesting pesticides recently applied to blooms they pollinate.

The prevention of poisonings entails alertness, knowledge and care not only on the part of agricultural growers, but on the part of  lawn care professionals and home gardeners.

My personal favorite (as you might guess!) on the list of ways growers can protect the bees essential to their crops is “Consider alternatives to pesticides.”

Below is some material from this publication:

Causes of Bee Poisoning in Pacific Northwest and California

Highly toxic insecticides with residual toxicity longer than 8 hours are responsible for most bee poisoning incidents reported on the West Coast, primarily those in the following chemical families:

■■Organophosphates (such as acephate, azinphosmethyl, chlorpyrifos, diazinon, dimethoate, malathion, and methamidophos)

■■N-methyl carbamates (such as carbaryl (or Sevin)

■■Neonicotinoids (such as clothianidin, imidacloprid, and thiamethoxam)

■■Pyrethroids (such as deltamethrin, cyfluthrin and Lambda-cyhalothrin).

Most bee poisoning incidents occur when:

■■Insecticides are applied when bees are foraging

■■Insecticides are applied to bee-pollinated crops  during bloom

■■Insecticides are applied to blooming weeds in  orchards or field margins

■■Insecticides drift onto blooming plants adjacent  to the target crop

■■Bees collect insecticide-contaminated pollen (such as corn), nectar (such as cotton or  mint), or other materials from treated crops that do not  require bee pollination

■■Bees collect insecticide-contaminated nectar from plants treated with systemic pesticides

■■Bees collect insecticide-contaminated nesting  materials, such as leaf pieces collected by  alfalfa  leafcutting bees

■■Bees collect insecticide-contaminated water (from drip tape or chemigation, for example)

■■Beekeepers and growers do not adequately  communicate

Pesticide poisoning isn’t always obvious

Delayed and chronic effects, such as poor brood development, are difficult to link to  specific agrochemicals, but are possible when stored pollen, nectar, or wax comb become contaminated with pesticides. Severely weakened or queenless colonies may not survive  the winter.

Beekeepers may request a laboratory analysis of dead bees to determine if pesticides were responsible for an incident. State agriculture departments in Oregon, Washington, and Idaho, and the pesticide regulation department in California, investigate suspected bee poisoning incidents (see original document for contact information).

Thanks to all of you who are helping care for our pollinators with your personal choices!

5 Comments leave one →
  1. solarbeez permalink
    October 28, 2013 9:18 am

    Where does Round-up fit in this list? So many people use it (not us) but some beekeepers in the club say you can use it if you spray at night when the bees are in their hives.

    • October 28, 2013 11:59 am

      You raise a very important question given the prevalence of Round Up use and the claim of its lack of toxicity (which creates more usage in turn).
      Though I am not aware of any studies specifically focused on bees and Round Up (glyphosate), a number of beekeepers’ will tell you negative experiences with the use of Round Up near their hives.
      NCAP’s fact sheet on Round Up is based on solid scientific research, and cites some serious concerns about neurotoxic effects, hormone disruption, gene mutation, and cancer with Round Up exposure in mammals or mammal cells–even in some cases with relatively low levels of exposure. Toxic effects of Round Up have been documented on fish, birds, other insects (fruit flies), spiders, and amphibians. Important data on the negative effects of Round Up– though not yet fully substantiated and analyzed– is coming out of Argentina and India, where the use Round Up ready crops has created substantial exposure to Round Up on the part of agricultural workers. There are claims of severe harm resulting there.
      On another environmental front, Round Up does not seem to break down as quickly as claimed. Its persistence in soil ranges up to 174 days in some tested samples. Moreover, the EPA does not regularly test water for glyphosate contamination, but in particular agricultural areas, glyphosate or its toxic relatives have been found in two-thirds of water samples– indicating that it is fairly persistent in the water table.
      The one thing that can be said for it is that it so far seems less toxic than the 2-4 D formulations found in Weed and Feed products.
      I personally wouldn’t use either one around my bee hives.

  2. permalink
    December 14, 2013 3:45 pm

    I know I need bees – the question I have is how to keep my vine borers out of my pumpkin and squash plants – have used Sevin 1-2 times per year – also want to know if same chemicals that kill my grubs are killing bees – I see no product names besides Sevin that I recognize – have a bee man a couple doors down, and he just wants everyone to have weeds for his bees to keep them producing – there need to be a lot more info about what is safe and will work – just taking swings at Big Chemical would need some easy to understand information to make the public more useful…

    • December 14, 2013 4:43 pm

      Certainly Sevin will kill bees if there are bees around when you apply it. However, Sevin also is relatively quick to degrade. We have quite a bit of understanding about these chemicals, and bee keepers have been trying to figure out how to coexist with farmers over their use for quite a while. Take a look at the table I came up with comparing pesticides over on my personal website:

      Bees like squash blossoms, so it is hard to avoid killing bees if you are treating with a spray that gets on the blossoms when bees are around. Things you could do would be to cover the plants you need to treat for a few days after treatment. Apply in the late evening after the bees have gone home – then cover the plants for a few days for best bee protection.

      These approaches will work for insecticides like Sevin (carbamate) because they are quick acting, require a toxic threshold to work, degrade quickly, and are not particularly toxic well below threshold.

      Some neonicotinoids are much more persistent, are harmful and very low residual doses, and are applied in a way that will naturally be present in bee-gathered products. That’s why we don’t like these!


  3. December 14, 2013 5:40 pm

    I just want to thank Steve for his thoughtful approach in searching for good information.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: