New research suggests that pesticides can have a negative effect on honeybees and wild bees in an agricultural landscape.

Neonicotinoids are used for seed dressing of rapeseed, to protect the young plants against flea beetles. Two years ago, this type of pesticide has been restricted by the EU for crops that are attractive to bees.

Researchers at Lund University found that neonicotinoids has a negative impact on wild bees. This is a serious matter because wild bees play an important role in pollination of crops. Wild bees include both bumblebees and solitary bees.

"We saw a clear negative impact on growth and ability to reproduce in bumblebee colonies near treated rapeseed fields," Maj Rundlöf, coordinator and principal investigator for the field study , said in a statement.

As well as problems with growth and reproduction, researchers also observed fewer wild bees on the treated rapeseed fields. However, the researchers found no negative effect on colony growth of honeybees.

The findings demonstrate the need for new ways to evaluate risks in conjunction with the approval of pesticides.

"If we only investigate how a new pesticide affects honeybees, that is not sufficient to predict the consequences for wild bees in a real landscape," Rundlöf said.

Thorsten Rahbek, project manager at the Swedish Board of Agriculture, said the findings demonstrate how detrimental it is to use clothianidin on rapeseed.

"We need alternative preparations and new cultivation methods if we are to continue growing spring rapeseed in Sweden," Rahbek added.

The findings are detailed in the journal Nature.