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New Water Quality BMPs Available for Neonicotinoids

By: Kathleen Hall (Research Scientist, Minnesota Department of Agriculture) & Bob Koch (Extension Entomologist, University of Minnesota)

In 2020, the Commissioner of Agriculture officially designated two neonicotinoid insecticides, clothianidin and imidacloprid, as “surface water pesticides of concern” due to detections of these active ingredients at elevated levels in surface waters in Minnesota. To address water quality concerns, the Minnesota Department of Agriculture (MDA), in coordination with the University of Minnesota Extension, developed “Water Quality Best Management Practices for Agricultural Use of Clothianidin & Imidacloprid.” The best management practices (BMPs) are designed to prevent the contamination of water resources by clothianidin and imidacloprid from direct insecticide applications as well as treated seeds.

Examples of promoted practices include:

         Scouting fields regularly and using economic thresholds to help determine if, when, and where to apply;

         minimizing seed dust generation and drift by avoiding planting treated seed during windy conditions (>15 mph) and when the wind is blowing toward nearby waterbodies; and

         maintaining grass or vegetation buffers near tile inlets and in drainage ditches.

The water quality BMPs for agricultural use of clothianidin and imidacloprid are a companion to the “Water Quality Best Management Practices for All Agricultural Insecticides.” The MDA has also developed stewardship guidelines and BMPs for the general neonicotinoid class of insecticides to protect insect pollinators. All pesticide BMPs are available on the MDA’s Pesticide BMPs webpage.

Use in Agriculture

In Minnesota, clothianidin (Poncho, Belay) and imidacloprid (Leverage 360, Gaucho) are used to manage insect pests on a variety of agricultural crops including soybean, corn, sugar beet, and potatoes. Clothianidin and imidacloprid are also used in urban settings on sites such as residential lawns, trees, and ornamentals. These insecticides can be applied through foliar sprays, soil treatments, and chemigation, but they are particularly popular as seed treatments.

Since their introduction in the 1990s, neonicotinoids have become the most widely used class of insecticides in the world. While neonicotinoids are useful tools for managing insect pests, chemicals in this class often have properties, such as high solubility in water, that favor movement to nearby waterbodies or groundwater. Neonicotinoids, including clothianidin and imidacloprid, are highly toxic to aquatic invertebrates and have the potential to cause negative effects at very low concentrations in rivers and streams. Therefore, it is particularly important to take actions to prevent the contamination of nearby waterbodies when using these insecticides.

Detections in Water

The MDA monitors waters throughout the state for over 180 pesticide compounds, including clothianidin and imidacloprid. Both insecticides have been detected in groundwater and surface waters, such as rivers and streams, in Minnesota. While concentrations in groundwater are low compared to human health-based guidance values from the Minnesota Department of Health, concentrations in rivers and streams have been found above the Environmental Protection Agency’s chronic aquatic life benchmarks for aquatic invertebrates. More information on surface water detections is available in the following handout: “Detection Patterns of Neonicotinoids in Minnesota Rivers and Streams, 2018-2022.” Annual monitoring reports and additional information about the MDA’s monitoring program can be found on the MDA’s website.

Reference to commercial products or trade names is made with the understanding that no discrimination is intended, and no endorsement is implied.

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