Tuesday, June 10, 2014

Garden Toxins, Honey Bees, and Agriculture

Many people enjoy having a garden in their yard of even on an apartment porch or balcony. It's a relaxing way to enjoy nature. But did you know that the choices you make in your garden can affect larger ecosystems and even agriculture?

With plants come insects - some beneficial, and some that might harm your plants. To protect their plants, some people use insecticides. One of the most common classes of insecticide chemicals is neonicotinoids. This type of chemical is structurally similar to nicotine, and it works by damaging the central nervous system (similar to the brain in humans and other complex animals).

Of course, honey bees are insects, too, but we want honey bees to stay alive. Neonicotinoids were tested for lethal effects in bees and thought to be safe because they did not kill bees during the studies. However, more recent studies have concluded that, while neonicotinoids do not directly kill bees, they have serious nonlethal effects. They cause decreased levels of certain enzymes, like acetycholinesterase, that are necessary for the nervous system to function correctly. After ingesting neonicotinoids along with pollen, or even absorbing the chemicals across their skin, bees show behavioral changes, they lose sensitivity to smells, and their learning and memory is impaired. Bees rely on smells and memory to gather food, so these changes can indirectly kill bees.

Honey bees pollinate a lot of plants, including many crops that are grown to feed humans. A decrease in honey bee populations harms the economy and makes some crops more expensive and less available. It also harms the environment by reducing the populations of many plants, which then reduces the availability of food and shelter to the animals that depend on these plants.

When you are working on your garden, try to avoid using chemical insecticides. Read the label of any chemicals that you do use. In the United States, the Environmental Protection Agency requires neonicotinoids to be labeled with a warning that they harm bees.

Cresswell, J. E. (2011). A meta-analysis of experiments testing the effects of a neonicotinoid insecticide (imidacloprid) on honey bees. Ecotoxicology, 20(1), 149-157.
Boily, M., Sarrasin, B., DeBlois, C., Aras, P., & Chagnon, M. (2013). Acetylcholinesterase in honey bees (Apis mellifera) exposed to neonicotinoids, atrazine, and glyphosphate: laboratory and field experiments. Environmental Science and Pollution Research, 20(8), 5603-5614.
El Hassani, A. K., Dacher, M., Gary, V., Lambin, M., Gauthier, M., & Armengaud, C. (2008). Effects of sublethal doses of acetamiprid and thiamethoxam on the behavior of the honey bee (Apis mellifera). Archives of Environmental Contamination and Toxicology, 54(4), 653-661.
Stankus, T. (2008). A review and bibliography of the literature of honey bee colony collapse disorder: A poorly understood epidemic that clearly threatens the successful pollination of billions of dollars of crops in America. Journal of Agricultural & Food Information, 9(2), 115-143.

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