A test developed by the Hygienic Laboratory can detect very low levels of insecticides that have been linked to the decline in bee populations. The laboratory developed the test in 2014 to test water for neonicotinoid insecticides, which are allegedly highly toxic to bees. From July 2014 to July 2015, the number of samples received for this test increased by 63 percent.

Studies by researchers at the Harvard School of Public Health and other institutions have shown that these insecticides – used to treat corn and soybeans in Iowa and elsewhere – could play a role in colony collapse disorder, which has decimated honey bee colonies over the past decade.

"The amount of insecticide on one corn seed is enough to kill an entire colony," said John Vargo, environmental lab scientist, adding that other factors, such as parasitic mites, also are thought to play a role in colony collapse disorder.

“Acute toxicity for most of these neonicotinoid insecticides by oral ingestion is estimated to be about 3-5 ng (nanograms),” Vargo said.

“The effects of long-term exposure to less than lethal concentrations of the pesticides is not known. The amount that we can detect in the test would be considered a concentration lower than a lethal amount.”

Seven neonicotinoid insecticides are included in the test: acetamiprid, clothianidin, dinotefuran, imidacloprid, sulfoxaflor, thiacloprid, and thiomethoxam. All of these chemicals can be detected, quantified and reported at concentrations as low as 0.020 micrograms per liter.

Besides providing honey, bees do much of the work in pollinating a wide variety of crops, with pollinators responsible for every third bite of food we eat.

Vargo said the lab first began testing for neonicotinoids at the request of the Iowa Department of Natural Resources.

Testing procedures, which use high performance liquid chromatography with tandem quadrupole mass spectrometric detection (LCMSMS), were developed at the Hygienic Laboratory.

The rapid and sensitive test can detect neonicotinoid insecticides at very low levels in surface, drinking and ground water.

Vargo said the lab initially tested surface water for the Iowa DNR in areas where water had pooled in farm fields after rain. These samples showed positive detection of select neonicotinoids.

The lab has since tested other samples for the DNR, as well as a few additional requests, he said. "This technique is highly specific to the chemicals being tested," Vargo said.

He noted that the procedure, which can cost $300 to $400, involves injecting water samples into the instrument, which are then analyzed.

Neonicotinoid insecticides are commonly used in seed treatments to protect the seed as it germinates and begins to grow. The amount of neonicotinoid insecticides applied to seeds range from a rate of 0.25-1.25 milligrams of active ingredient per seed.

The U.S. Environmental Protection Agency estimates that nearly 35 percent of soybean seeds and more than 95 percent of corn seeds have been treated with one or more neonicotinoid insecticides, with imidacloprid, thiomethoxam, and clothianidin being used most frequently.

Neonicotinoid insecticides also may be applied to the foliage of infested plants.

The insecticides are highly soluble in water and somewhat persistent in the environment, making it likely that the chemicals will be transported to groundwater or surface water through rain or irrigation.

Vargo said bees may encounter neonicotinoids from dust containing pesticides at the time of seed planting, from pesticide leaching from treated seeds in water, and from spray drift from foliar applications to plants.

The EPA does not require public water supplies to test for neonicotinoid insecticides as part of the Safe Drinking Water Act, but Vargo said the tests can be useful for beekeepers, environmental groups and farmers who rely on bees to pollinate their crops.

Limited data is available on the impact of neonicotinoid insecticides via puddled water on pollinators, but a Canadian study showed that honey bees and native pollinators face an unprecedented cumulative exposure to the insecticides from combined residues in pollen, nectar and water.

Representatives of the Iowa Department of Natural Resources noted that the results of the farm field study are in the review process and awaiting publication.