JACKSON, Tenn. – Neonicotinoid seed treatments provide significant economic benefits in Mid-South soybean production, according to a 10-year study conducted by scientists from four universities.
The results of the meta-analysis, published in the Journal of Economic Entomology, come as neonicotinoids, a widely-adopted class of insecticides, face increased scrutiny from both environmental groups fearing their impact on pollinators and regulators who question the economic advantage they provide. Neonicotinoids are currently being reviewed by the U.S. Environmental Protection Agency.
“Most scientists will agree that there are critical knowledge gaps concerning neonicotinoids and their impact on bees,” says Scott Stewart, Integrated Pest Management Coordinator with the University of Tennessee Institute of Agriculture (UTIA). “What we do know is that at-planting insecticides are vital to crop production, particularly in the Mid-South where we see pressure from multiple pest species. This study shows neonicotinoid seed treatments provide a clear value to the soybean producers of our region.”
Researchers from Mississippi State University, UTIA, the University of Arkansas and Louisiana State University analyzed 170 trials over 10 years comparing soybean seed treated with neonicotinoid and a fungicide with soybean seed treated only with a fungicide. The soybeans treated with neonicotinoid averaged a 2-bushel per acre yield advantage over fungicide-only treated soybeans. The neonicotinoid seed treatment also resulted in a $12 per acre net return over soybeans where no insecticide seed treatment was used.
“While soybean may not be as responsive to neonicotinoid seed treatments as corn or cotton, we’re still talking about a 3-5% yield advantage, which is significant,” says Stewart. “For many farmers who are operating on extremely tight margins, that 5% could be what keeps them in business.”
Soybeans are an economically significant crop in the Mid-South. In 2015, more than 9 million acres of soybeans were planted throughout the region. In Tennessee alone, soybean production contributed more than $1 billion in economic activity.
Neonicotinoids have been implicated as a cause of declining honeybee health. However, a field study led by Stewart and published in Environmental Science and Technology in 2014, found that the contributions of neonicotinoid seed treatments to this phenomenon were relatively low. The study evaluated the potential exposure of pollinators to neonicotinoid insecticides used as seed treatments on corn, cotton and soybeans. The results showed that concentrations of the insecticides in the crops’ flowers, pollen and nectar were “well below defined levels of concern.” In soybean flowers, concentrations were “nondetectable.”
“Because neonicotinoid insecticides and pollinator health are hot topics, there is a spotlight on risks without much consideration of benefits,” says Stewart, “but our previous research shows pollinators are not being exposed to the insecticides used on seed when they visit soybean flowers.”
Researchers will continue to evaluate both the economic benefits of neonicotinoid seed treatments as well as their impact on pollinator health.