While modern synthetic pesticides are developed to reduce impacts on non-target organisms, two recent papers published in Science have brought to light new evidence of the damaging effects of pesticides on bee colonies.
Both papers investigated the impact of the use of neonicotinoid pesticides on bees. When sprayed on crops such as oilseed rape, maize and sunflower, these pesticides spread throughout plant tissues including into nectar and pollen, and as such are directly available to bees, although in trace amounts.
The first paper published in March 2012, found that bumblebee colonies exposed to field-realistic levels of the neonicotinoid imidacloprid suffered reduced growth rates and an 85% reduction in the production of queen bees.
The second paper, published in September 2012, found that despite neonictinoids not causing direct mortality, they did impact homing ability of honey bees and thus their ability to locate their colony. Other papers have reported similar behavioural effects such as memory and learning dysfunction and changes to navigation skills.
With increasing recognition of the importance of bees and other pollinators to our food supply, for example in the UK pollination is worth £430 million to the economy, these new findings are adding to the picture that is building of the causes of Colony Collapse Disorder. While we may have to wait for the exact answer, action looks likely. The Agriculture and Rural Development Committee has requested the European Commission produce an action plan to conserve bees.