A new study by the Royal Society (The UK national academy of science) says that:-

“Although laboratory trials report deleterious effects in honeybees at trace levels of neonicotinoids, field surveys reveal no decrease in the performance of honeybee colonies in the vicinity of treated fields. Here we provide the missing link, showing that individual honeybees near thiamethoxam-treated fields do indeed disappear at a faster rate, but the impact of this is buffered by the colonies’ demographic regulation response.”

http://rspb.royalsocietypublishing.org/content/282/1819/20152110