Individual worker behaviour and colony success are both affected when bees are exposed to a combination of pesticides, according to research conducted by Dr Richard Gill and Dr Nigel Raine at Royal Holloway, University of London.
This research, published in Nature, investigated social bumblebee colonies which rely on the collective performance of numerous individual worker bees. It showed that chronic exposure to two commonly-used pesticides (a neonicotinoid and a pyrethroid), at concentrations approximating field-level exposure, impaired natural foraging behaviour and increased worker mortality. This led to significant reductions in colony success, and increased rates of colony failure.
Bees are typically exposed to numerous pesticides when collecting pollen and nectar from crops, and this is the first study to examine the potential effects of exposure to a combination of pesticides under realistic field conditions.
While recent studies have investigated the role of pesticides on either individual bee behaviours, or the impact on whole colonies, how changes to individual behaviour could have knock-on effects for the colony has not previously been shown.
Dr Raine said: "There is an urgent need to understand the reasons behind current bee declines as they are essential pollinators of many agricultural crops and wild flowers. We rely on these insects to produce most of the food we eat and maintain the landscapes we enjoy".
"Previous studies investigating the possible role of pesticides in current bee declines have focused on honeybees, but it is also crucial that we understand how pesticides affect other bee species," added Dr Gill.
This study mimicked realistic scenarios in which 40 early stage bumblebee colonies received four-week exposure to two pesticides that are frequently encountered when foraging on flowering crops: the neonicotinoid 'Imidacloprid' and the pyrethroid 'lambda-cyhalothrin'.
|Contact: Rob Dawson|
Biotechnology and Biological Sciences Research Council