The risks of pesticides to pollinators

UNIVERSITY OF MINNESOTA EXTENSION - www.extension.umn.edu

Pesticides used to kill pests, diseases, and weeds can harm pollinators and other beneficial insects. They can remove important flowers (food) and impact bee reproduction, navigation and memory.

Exposure to pesticides can also multiply the effects of other stressors on pollinator populations, such as loss of habitat and exposure to pathogens and diseases. 

Exposure pathways

Pollinators may be exposed to pesticides in numerous ways, including direct contact with spray residue on plants, by eating contaminated pollen and nectar, or through exposure to contaminated nesting sites or materials.

Direct contact occurs when pesticides land directly on pollinators. The risk of direct contact is highest when pesticides are applied on or near flowering plants, be they crops or weeds.

Residue contact occurs when pollinators visit flowers or walk on leaves that have been previously treated with pesticides. Butterflies can be at risk of exposure when laying eggs on host plants that have been treated with pesticides.

Solitary bees risk exposure when collecting plant material or soil used to construct nests. Wild bees often nest in areas between row crops, in brush piles, or overgrown areas at field edges. These sites can become contaminated when pesticides are applied nearby.

Pesticide contamination is widespread. More than 90% of pollen samples from bee hives and more than 90% of stream samples are contaminated with more than one pesticide. It is critical that we work to reduce the use of pesticides and minimize the risk to pollinators where they are used. 

Use low-impact pesticides

Choose insecticides that are highly selective to a specific type of insect and so have low toxicity for others. Low-impact pesticides break down rapidly after application and, therefore, have minimal impact on pollinators and natural enemies. However, using these products requires some knowledge about their relative toxicity to beneficial insects and their potential to cause leaf or flower injury.

Find out more about how you can create and support healthy habitats for pollinators.

Michigan State University has more information on pesticide use and pollinators.