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Herbicides influence more than plants

Posted: July 30, 2013

Eric briefly describes some of his work this summer
A healthy Eupatorium perfoliatum plant (left) and a plant suffering severe injury from a sub-lethal dose of dicamba (right; note the stem curling on the injured plant).

A healthy Eupatorium perfoliatum plant (left) and a plant suffering severe injury from a sub-lethal dose of dicamba (right; note the stem curling on the injured plant).

Through out the world, herbicides are the most common type of pesticides applied in agricultural systems.  While they are used for killing weeds, they can also influence other organisms, including insects, both directly and indirectly.  Recently the widespread overuse of the herbicide glyphosate, the active ingredient in Roundup®, has led to development of glyphosate resistance in 24 weed species over tens of millions of acres of farmland worldwide.  Because of this widespread development of resistance to glyphosate, agricultural industry is developing soybeans, corn, and cotton that are genetically modified to be resistant to the herbicides dicamba and 2,4-D.  These two herbicides are highly prone to drift through a variety of mechanisms and are frequently responsible for non-target damage to crops and non-crop areas.  Because of this propensity to move offsite and cause non-target damage, many folks are concerned about the likely increased use of these herbicides and the associated increased potential for non-target effects from herbicide applications.

Last year I was awarded an EPA Science to Achieve Results (STAR) Fellowship to study the potential effects of the herbicide dicamba on insect populations.  This work has been a great collaboration with Drs. Dave Mortensen and Franklin Egan of the Weed Science Lab at Penn State.  This summer, I will be continuing my work looking at herbicide-insect interactions by working with dicamba and honey bees.  My summer experiments are consisting of one field study to observe honey bee visitation to dicamba damaged Eupatorium perfoliatum (common boneset), and a lab study testing the influence of dicamba on honey bee behavior.  I am anxious to get my results, but I still have a bit more work to do.  This research is especially important as honey bees have been suffering declines nationwide and because of the likelihood that the use of these herbicides will become much more common, resulting in more exposures to this potential stressor.

--Eric Bohnenblust, 23 July 2013