Imidacloprid was provided in a sucrose solution at levels that could be found in nectar and lambda-cyhalothrin was administered following label guidance for field spray applications. Bees were able to forage in the field providing a realistic behavioural setting, and the foraging behaviour of individual workers was recorded using radio frequency identification (RFID) tagging technology.
The researchers found that bees exposed to imidacloprid were less able to forage effectively, particularly when it came to collecting pollen. This meant treated colonies had less food available to them, so could not raise as many new workers. On average, the percentage of workers leaving the colony and then getting lost was 55% higher in those receiving imidacloprid than those that were not exposed to pesticides. The results of this study also indicate that combinatorial exposure to pesticides increases the tendency of bee colonies to fail.
Dr Gill commented that: "The novelty of this study is that we show how the sublethal effects of pesticide exposure affects individual bee behaviour with serious knock-on consequences for the performance of the colony as a whole".
Dr Raine added: "Policymakers need to consider the evidence and work together with regulatory bodies to minimize the risk to all bees caused by pesticides, not just honeybees. Currently pesticide usage is approved based on tests looking at single pesticides. However, our evidence shows that the risk of exposure to multiple pesticides needs to be considered, as this can seriously affect colony success".
|Contact: Rob Dawson|
Biotechnology and Biological Sciences Research Council