Neonicotinoids are a fairly new class of insecticides that have become widely used in recent years, including for our favorite crops in Illinois, corn and soybeans. In fact, one of them (imidacloprid) is reportedly the most widely used insecticide in the world. As you might guess from their name, neonicotinoids are chemically similar to nicotine and, sort of ironically, are especially effective against sucking insects. The most controversial aspect of neonicotinoids is that they have been linked to honey bee colony collapse.

A new study by researchers at the USGS have found that many U.S. streams have detectable neonicotinoids. It was a nationwide study (subscription may be required to view paper); of most interest to us in Illinois are results from Iowa. Six sites were selected across the state, and all had neonicotinoids in them. The concentrations were very low (median 23 ng/L, or parts per trillion). The researchers found that these compounds were transported conservatively (i.e., were not slowed down in the environment) throughout the stream reach that was studied in Iowa.

More evidence that whenever we apply a compound at the land surface, some of that compound almost always finds its way into our water sources. At such low concentrations, it’s hard to know if they pose any kind of threat to the aquatic ecosystem; that research hasn’t been done yet.