The research showed that queen bees exposed to neonicotinoid pesticides were 26% less likely to be able to start a new colony.
Experiments were conducted on oil seed rape in fields in Oxfordshire.
The researchers said: "We show for the first time that exposure to field-relevant levels of the neonicotinoid pesticide thiamethoxam significantly reduces successful colony founding in B. terrestris queens. Two weeks of insecticide exposure resulted in a shift in the timing of colony initiation, and ultimately a 26% reduction in the proportion of queens that laid eggs by the end of the experiment. These results add significantly to our understanding of the impacts of neonicotinoid on a key life-stage in an essential agricultural pollinator. Including this 26% reduction in models of population dynamics indicated a dramatically increased risk of population extinction after pesticide exposure."
NFU acting chief science and regulatory affairs adviser Chris Hartfield said: "This interesting new research from Royal Holloway University is another example of bees being artificially dosed with neonicotinoids, at concentrations towards the high end of what is typically observed in the field. Being fed only dosed food in this way is an unnatural situation – indeed, field observations during this new study showed that bumblebees do not feed exclusively on treated oilseed rape crops – in fact, one species was only seen feeding on wild flowers.
"While the study showed exposure to the neonicotinoid reduced the proportion of queen bees laying eggs by 26 per cent, it didn’t result in any impacts on the actual number of adult offspring the queens produced. When the 26 per cent figure was put into a statistical model it showed a theoretical increase in the risk of extinction, but couldn’t show precisely whether or not populations would go extinct.
"The big unanswered question remains whether the harmful impacts observed in studies like this occur in real-life field situations and cause actual population declines and we still don’t have that clear, definitive evidence.
"The last bumblebee species to go extinct in the UK – the short-haired bumblebee - disappeared several years before neonicotinoids came into use. In recent years this bee has been re-introduced to the UK, with the help of farmers.
"Farmers understand the importance of pollinators and the key role they play in food production. As a result, they have planted around 10,000 football pitches worth of flower habitat across the country to provide the food and environment bee populations need to thrive."