New Study Finds Common Crop Sprays Change Bee and Fish Behavior — Wider Ecological Risk

A recent study by the Helmholtz Centre for Environmental Research (UFZ) found that commonly used herbicides and insecticides can alter the behaviour of bees and freshwater fish, with potential consequences for pollination and aquatic food webs.

What the Researchers Did

Scientists analysed behavioural responses in bees and fish after exposure to sprayable plant protection products used in agriculture and gardening. They focused on species most likely to encounter these chemicals: pollinators that fly through treated areas and aquatic animals exposed when rain washes residues into local waterways.

Key Findings

Following exposure, the animals showed clear behavioural changes. Bees foraged less and processed nectar differently than normal — changes that could undermine colony functioning and reduce pollination efficiency. Fish also exhibited measurable behavioural alterations, which could cascade through freshwater food webs and threaten ecosystem stability.

"The effects that we were able to measure in these animal models suggest that the actual ecological effects of plant protection products are much more far-reaching than previously assumed," said Martin von Bergen, a biologist at UFZ and joint principal investigator of the study.

The research team emphasised that while some low-concentration behavioural tests are included in chemical risk assessments, these tests often lack complexity and are not consistently mandatory.

"Although animal behavior tests following exposure to low concentrations of chemicals are already included in the risk assessment of chemicals in some cases, these tests are not complex enough and are typically not mandatory," said Cassandra Uthoff, lead author of the study and a doctoral student at UFZ.

Implications and Next Steps

The findings suggest regulators and manufacturers should expand and strengthen behavioural testing during product development and review. Longer-term studies are needed to understand persistent and population-level effects. In the meantime, measures that reduce non-target exposure — such as targeted application, buffer zones near waterways and careful adherence to label instructions — can help limit unintended impacts on wildlife.