Widely used crop pesticides are damaging animal behaviour on a large scale

Common farm chemicals used to protect crops may be harming bees and fish by changing the way they behave, a new study by the Helmholtz Centre for Environmental Research (UFZ) in Germany has found. Scientists say this could have a long-term impact on the environment and wildlife.

The study, published in the journal Environment International, looked at how insecticides, herbicides, and fungicides affect two species - the honeybee (Apis mellifera) and the zebrafish (Danio rerio). Both are used as model animals to study environmental effects.

“Wild bees and other pollinators can come into contact with quite high concentrations shortly after spraying. But animals in aquatic habitats are also at risk,” said Professor Martin von Bergen, one of the study’s lead researchers, and added, "rainfall gradually washes plant protection products into the surrounding waters. They don't simply remain and only affect the area where they are applied".

The team found that honeybees exposed to insecticides became less active in collecting nectar and showed changes in how they processed it. When treated with fungicides and herbicides, bees spent less time caring for their young. These changes could affect pollination and the health of entire colonies.

Chemical mixes trigger strange reactions in fish
In the case of fish, the zebrafish embryos showed unusual movements and changes in learning behaviour after exposure to chemical mixtures found in the environment. At lower levels, the herbicide’s effects were dominant, but at higher levels, the behaviour changed and started to match the effects of the fungicide.

According to the researchers, the study shows that chemical mixtures can affect animal behaviour even when the chemicals are present in small, “safe” amounts. They believe that such behavioural changes need to be included in future safety tests for these products.

Experts say the real ecological impact of crop protection chemicals appears to be much greater than what was previously thought. Professor von Bergen and his team are urging regulators to include more complex behavioural testing to better protect bees, fish, and other non-target species.