Pesticides: Neonicotinoid-laced Nectar

Bees ‘prefer’ neonicotinoid-laced nectar

Bees may be doomed to consume nectar contaminated with neonicotinoid pesticides, according to new behavioural studies carried out by UK researchers. In contrast to previous research, behavioural studies suggested the insects do not avoid feeding on neonicotinoid-treated plants, and may even be choosing to do so, ingesting far higher amounts of the pesticides than most toxicity studies account for.

Systemic pesticides of the neonicotinoid family were once hailed as a green alternative, as the coating of seeds is more targeted than the blanket spraying of earlier products, and tests seemed to suggest that their acute toxicity to useful insects like bees is low. But since the emergence of ‘colony collapse disorder’ in 2006-07, researchers have revisited neonicotinoids, and uncovered evidence that they may be linked to declining bee populations. Several studies have shown that sub-lethal effects on insect brains can interfere with the insects’ ability to navigate and communicate, which are vital for the survival of colonies in the long term.

Bees may prefer to feed on nectar contaminated with neonicotinoids, so their exposure could be higher than previously assumed © Jon Carruthers

Two years ago, these concerns led to an EU ban on the use of certain neonicotinoids on flowering crops. The ban runs until December this year, and the European Commission will have to decide soon whether to renew it. A key argument of those who originally opposed the ban, including the UK government, was that bees in their natural environment would choose not to feed on the nectar from neonicotinoid-treated plants. This view was backed up by a UK study in 2013, but new research combining behavioural observations and neuroscience has cast doubt on this conclusion.