Even with tight regulations, pesticides are still damaging bee colonies

European researchers are ringing the alarm about human and farming activities damaging bee populations.

An international team has investigated 316 bumblebee colonies across eight European countries, finding that despite rigorous risk assessments, European bees are still being damaged by pesticide use.

“With the largest experimental field deployment of any pollinator, we see that bumblebees encounter multiple pesticides in agricultural landscapes, resulting in fewer offspring,” said Dr Charlie Nicholson, co-lead author and postdoc at Lund University.

“On top of this, pesticides do more harm in landscapes with less habitat.”

The European Union has largely banned neonicotinoids, a controversial pesticide implicated in colony collapse in bees – from use outside of green houses. But many other types of insecticides, as well as one type of neonicotinoid which is thought to have a low risk to bees, are still being used.

This is more stringent than some other locations. For example, neonicotinoids are registered for restricted use in Australia while the US Environmental Protection Agency has some management measures in place.

The European researchers put 316 colonies near apple and oil seed crops across the different countries, and then took pollen from inside the hive and assessed it for types of pesticides.

They were able to map these different pesticides to the colony weight before, during and after crops bloomed. A lower colony weight means less offspring, food and bees overall.

The results weren’t promising. They found that common pesticides were reducing the colony weight, and those risks were worse in areas with more agriculture and less wild plants.

“The current assumption of pesticide regulation – that chemicals that individually pass laboratory tests and semi-field trials are considered environmentally benign – fails to safeguard bees and other pollinators that support agricultural production and wild plant pollination,” the researchers write in their new paper – published in Nature.

“These findings support the need for post approval monitoring of both pesticide exposure and effects to confirm that the regulatory process is sufficiently protective in limiting the collateral environmental damage of agricultural pesticide use.”

This research is part of a larger cross-country European project called PoshBee which is monitoring and trying to improve bee health.

“Bumblebees, and other animals, do not recognise international borders, and to protect them, we need to take a similarly international approach,” said PoshBee coordinator, Professor Mark Brown, from the Royal Holloway University of London.

“The scale of this work provides a step-change in our understanding of the impact of agrochemicals on pollinator health.”