A new study, which was published August 16 in the journal Nature Communications, also looks at an 18-year timespan that begins before neonicotinoids were introduced in 2002.
That means the researchers could actually establish a baseline for how bees were doing before farmers began widely using the chemicals.
Wild bee declines have been ascribed in part to neonicotinoid insecticides. While short-term laboratory studies on commercially bred species (principally honeybees and bumblebees) have identified sub-lethal effects, there is no strong evidence linking these insecticides to losses of the majority of wild bee species.
We relate 18 years of UK national wild bee distribution data for 62 species to amounts of neonicotinoid use in oilseed rape.
For a few bees, the scientists estimate about a fifth of their population declines was due to neonicotinoids.
That’s not enough to kill off bees taken by itself. But pesticides aren’t the only challenge bees are facing. Climate change, differences in how we use the land and what plants they can feed on, and parasites and diseases that infect bees are also putting a dent in populations.