New Scientist reports that bees have been exposed to growing levels of toxicity from pesticides over 25 years, despite the amount used falling. The toxic exposure is based on US data but probably applies to other countries too.
Countries should consider following Denmark’s lead with “toxicity taxes” on pesticides to encourage farmers to change which products they use, says one of the researchers behind the new findings.
In recent years, pesticides that precisely target crop pests have been linking to falling insect numbers, with the European Union banning outdoor use of several widely used pesticides known as neonicotinoids in 2018. In January, following its exit from the EU, the UK controversially allowed the emergency use of such “neonics” to kill aphids carrying a virus that threatens sugar beet.
“We saw people from media, politics and even scientists often talk about how the amount of pesticides changes [over time]. At the same time, we saw, as ecotoxicologists, that the toxicity of pesticides changed. Some insecticides used today are way more toxic to some groups of organism than ones used decades ago,” says Ralf Schulz at the University of Koblenz and Landau, Germany, who led the new research.
He and his team combined US government data on the weight of 381 pesticides used between 1992 and 2016 with their own index of the pesticides’ toxicity for different groups of species, from birds and mammals to pollinators and plants, to create a measure dubbed “total applied toxicity”. They found that for pollinators, plants on land and aquatic invertebrates such as dragonflies, this increased by about 80 per cent between 2005 and 2016, even though the weight of pesticides used fell.