A new study has found that insecticides have become significantly more toxic to honeybees over the last two decades.
Researchers from Dickinson College, Penn State and the University of Minnesota found that insecticides applied to U.S. crops have become about 120 times more toxic to honeybees in some Midwestern states.
The researchers believe that rising neonicotinoid seed treatments in corn and soy, two of Indiana’s top crops, could be the primary drivers of the change.
Neonicotinoids are the most widely used family of insecticides in the world.
In a 2017 study, Purdue researchers found that nearly every foraging honey bee in Indiana encountered neonicotinoids during corn planting season, but the insecticide did not improve crop yields.
According to the Christina Grozinger, a researcher involved in the study and director of Penn State’s Center for Pollinator Research, the toxicity of insecticides increased during the same period in which widespread declines in pollinator populations have been documented.
“Insecticides are important for managing insects that damage crops, but they can also affect other insect species, such as bees and other pollinators, in the surrounding landscape,” she told the National Science Foundation. “It is problematic that there is such a dramatic increase in the total insecticide toxicity at a time when there is also so much concern about declines in populations of pollinating insects.”
Last year, the U.S. Environmental Protection Agency expanded the use of sulfoxaflor, an Indiana-made insecticide known to be “very highly toxic” to honey bees.
The EPA is on the verge of reapproving the use of five other neonicotinoids that could have negative effects on the health of honeybees.