New Studies Blame Pesticides for Bee Decline They show 'big effects' in natural environment By Matt Cantor, Newser User Posted Mar 29, 2012 3:19 PM CDT 21 comments Comments A honeybee hovers over a flower in Chitwan National Park near Kathmandu. (Getty Images) (Newser) – Scientists have a new lead in the mystery of the disappearing bees. While pesticides had only a "trivial" effect on honeybee populations in lab experiments, a researcher says studies in natural settings have shown that the chemicals can have "big effects," reports the Guardian. Common pesticides known as neonicotinoids appear to double the number of bees that "disappear," or fail to return from foraging missions. The chemicals also cut the number of queens a nest produces by 85%. "Under the effects we saw from the pesticides, the population size would decline disastrously, and make them even more sensitive to parasites or a lack of food," says a researcher. Neonicotinoids are used on plants' seeds, which allow them to travel through the entire plant—including the nectar and pollen consumed by bees. Producers of the pesticides in question criticize the studies' methodology, saying it misrepresents how the chemicals are used in practice. The new studies are just the latest to identify possible bee killers.