Analysis contradicts claims that the environmental impact of pesticides is falling, say scientists.
The toxic impact of pesticides on bees and other pollinators has doubled in a decade, new research shows, despite a fall in the amount of pesticide used.
Modern pesticides have much lower toxicity to people, wild mammals and birds and are applied in lower amounts, but they are even more toxic to invertebrates. The study shows the higher toxicity outweighs the lower volumes, leading to a more deadly overall impact on pollinators and waterborne insects such as dragonflies and mayflies.
The scientists said their work contradicts claims that declines in the amount of pesticides used is reducing their environmental impact. The research also shows that the toxic impact of pesticides used on genetically modified crops remains the same as conventional crops, despite claims that GM crops would reduce the need for pesticides.
The research is based on the use and toxicity of 380 pesticides applied in the US from 1992 to 2016. The scientists said the same trend of lower volumes but greater toxic impact is likely for many regions in the world, but open-access data on pesticide use is not available in the EU, Latin America, China or Russia.
Pesticides are one factor cited by scientists for the plunging populations of some insects. Insects play vital roles in the ecosystems that sustain humanity, in particular by pollinating three-quarters of crops.
“Compounds that are particularly toxic to vertebrates have been replaced by compounds with less vertebrate toxicity and that is indeed a success,” said Prof Ralf Schulz, of the University Koblenz and Landau in Germany, who led the research. “But at the same time, pesticides became more specific, and therefore, unfortunately, also more toxic to ‘non-target organisms’, like pollinators and aquatic invertebrates.”