Bee colony collapse “more likely” after exposure to pesticides

Exposure to a mixture of pesticides is causing declines in bee productivity and numbers, according to a new study, with major implications for global food production.
The links between the pesticides sprayed by farmers on their crops and harmful impacts on bees have once again been exposed by a new study from researchers in the UK.
There have been growing concerns that bees were suffering falls in productivity and development (in simple terms, not collecting as much pollen and not being able to help nurture new bees) because of their exposure to pesticides when they were in the field.
So far governments in the US and Europe have been reluctant to take serious action to ban particularly harmful pesticides – only last month the UK government completed it’s own assessment of the evidence, concluding that there was not yet "unequivocal evidence" that pesticides were causing "serious" problems for bee populations.
A study led by Dr Richard Gill from the University of London, and published in the Scientific journal Nature, found exposure to multiple pesticides (the reality on farms today) increased the likelihood of bumblebee colonies eventually collapsing. 
Previous studies have looked at the impact of pesticides on honeybees but Gill believes that the smaller size of bumblebee colonies means they could be more susceptible to pesticide effects on foraging and survival, compared with larger honeybee colonies that may be able to ‘buffer’ such effects.
Any decline in bee population would have serious impacts on food production worldwide as they provide approximately 80% of insect pollination, helping pollinate crops such as apples and pears. 
As reported in chinadialogue recently, many farmers in China are already being forced to pollinate their crops by hand because of the collapse in bee and other pollinator numbers.
Gill expressed concern that current government regulation did not take into account the impact of exposure to multiple pesticides on bee populations, despite it being common in modern intensive agricultural systems.
"Pesticide regulatory bodies should consider carefully the evidence that we have provided," Gill told chinadialogue. "We show that sublethal concentrations exposed over a chronic period of time should be acknowledged and considered when drafting the guidelines for pesticide application in terms of the risk posed to pollinating insects (especially bees)."