Study: farmers using less pesticides, but more-concentrated varieties harm pollinators more

"American farmers are using smaller amounts of better targeted pesticides, but these are harming pollinators, aquatic insects and some plants far more than decades ago, a new study finds," Seth Borenstein reports for The Associated Press. "Toxicity levels have more than doubled since 2005 for important species, including honeybees, mayflies and buttercup flowers, as the country switched to a new generation of pesticides. But dangerous chemical levels in birds and mammals have plummeted at the same time, according to a paper in Thursday’s journal Science.

German scientists studied 381 pesticides used in the U.S. between 1992 and 2016 and factored in Environmental Protection Agency data about toxic dosages for eight kinds of plants and animals, combined with U.S. Geological Survey data about how much of the chemicals were used each year on dozens of crops. 

Newer pesticides "are aimed more toward animals without backbones to spare birds and mammals, but this means insects such as pollinators get poisoned," Borenstein reports. "The same goes for some land plants and for aquatic invertebrates including dragonflies and mayflies, which birds and mammals eat." The study's lead author said future studies should examine the harm higher up the food chain.