Friday, April 27, 2012

Bees, Butterflies, and Pesticides

Evidence is mounting that widespread use of supposedly "safe" chemical pesticides may lie at the root of the problems currently being experienced by beekeepers. One report can be found here. The study mentioned in this report found that feeding bees artificial nectar spiked with the neonicotinid insecticide imidocloprid in tiny amounts resulted in bee behavior like that associated with colony collapse disorder. While the maker of the insecticide, Bayer, debunks the study, I cannot help but wonder if we are ingesting this pesticide any time we consume a product containing high fructose corn syrup (HFCS). Traces of imidocloprid can be found in commercial HFCS, according to the author of the study.

Neonicotinid pesticides mimic the nicotine found in tobacco, a natural pesticide that affects a great many types of insects. Nicotine is particularly effective against the caterpillars of moths and butterflies, several of which feed on tobacco, tomatoes, potatoes and related crops. An anecdote from my garden a few years ago serves to demonstrate how effective nicotine is. During one particularly bad season for tomatoes, we inadvertently allowed a number of flowering tobacco plants (Nicotiana sylvestris) to grow too near the tomato patch. The sweet scented blooms of the tobacco attracted hornworm moths that laid eggs on both the tobacco and the tomatoes. The caterpillars started munching both types of plants, but those on the tobacco became stunted and died when they were about and inch and a half long, too small to do severe damage to the foliage. Those on the tomatoes, however, thrived, growing much larger and doing considerable damage before we could discover and remove them by hand.

One wonders, therefore, if the severe decline in butterfly abundance, observable to anyone who takes an interest in butterflies from one year to the next, might also be a result of chemicals in the environment. A decade old report found, for example, that pollen from corn genetically engineered to contain a pest-killing substance was harmful to monarch butterflies. How many other products that are commonly applied to lawns, flowerbeds and farms contribute similar effects? No one knows. But everyone agrees that butterfly populations are declining, and last March, this report appeared, suggesting that glyphosate, the active ingredient in herbicides such as Roundup, is seriously affecting monarchs and is turning up in humans, too.

There are a limited number of circumstances under which a home gardener might have to resort to chemical pesticide use. Situations involving noxious weeds already established on the property and ineracdicable by hand cultivation can be handled by spot treatment with glyphosate or triclopyr. Otherwise, I cannot think of a good excuse to use either herbicide.

I can think of NO circumstance under which I would resort to a chemical insecticide, with the possible exception of a termite infestation of my house. And then I would have the treatment done by a professional. In the garden, we have learned that proper husbandry and integrated pest management techniques suffice to protect our vegetable crops, and we only grow ornamental plants that are typically pest-free in our region when properly sited and maintained. Many of our plants are native to the southern Appalachians and have natural resistance to pests and disease.

All home gardeners should follow similar guidelines. Chemical pesticides are both expensive and harmful to wildlife.

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