"These troubling findings add to the urgency of reining in pesticide use to save biodiversity."

"Beetles and springtails have enormous impacts on the porosity of soil and are really getting hammered, and earthworms are definitely getting hit as well," said study co-author Nathan Donley, a scientist at the Center for Biological Diversity.

A study published Tuesday in the journal Frontiers in Environmental Science bolsters alarm about the role that agricultural pesticides play in what scientists have dubbed the "bugpocalypse" and led authors to call for stricter regulations across the U.S.

"It's extremely concerning that over 70% of cases show that pesticides significantly harm soil invertebrates."
—Tara Cornelisse, Center for Biological Diversity

Researchers at the University of Maryland as well as the advocacy groups Friends of the Earth U.S. and the Center for Biological Diversity were behind what they say is "the largest, most comprehensive review of the impacts of agricultural pesticides on soil organisms ever conducted." 

The study's authors warn the analyzed pesticides pose a grave danger to invertebrates that are essential for biodiversity, healthy soil, and carbon sequestration to fight the climate emergency—and U.S. regulators aren't focused on these threats.

"Below the surface of fields covered with monoculture crops of corn and soybeans, pesticides are destroying the very foundations of the web of life," said study co-author Nathan Donley, a scientist at the Center for Biological Diversity, in a statement.

"Study after study indicates the unchecked use of pesticides across hundreds of millions of acres each year is poisoning the organisms critical to maintaining healthy soils," Donley added. "Yet our regulators have been ignoring the harm to these important ecosystems for decades."

As the paper details, the researchers reviewed nearly 400 studies "on the effects of pesticides on non-target invertebrates that have egg, larval, or immature development in the soil," including ants, beetles, ground-nesting bees, and earthworms. They looked at 275 unique species, taxa, or combined taxa of soil organisms and 284 different pesticide active ingredients or unique mixtures.

"We found that 70.5% of tested parameters showed negative effects," the paper says, "whereas 1.4% and 28.1% of tested parameters showed positive or no significant effects from pesticide exposure, respectively."

Donley told The Guardian that "the level of harm we're seeing is much greater than I thought it would be. Soils are incredibly important. But how pesticides can harm soil invertebrates gets a lot less coverage than pollinators, mammals, and birds—it's incredibly important that changes."

"Beetles and springtails have enormous impacts on the porosity of soil and are really getting hammered, and earthworms are definitely getting hit as well," he said. "A lot of people don't know that most bees nest in the soil, so that's a major pathway of exposure for them."

Underscoring the need for sweeping changes, Donley noted that "it's not just one or two pesticides that are causing harm, the results are really very consistent across the whole class of chemical poisons."

Co-author Tara Cornelisse, an entomologist at the Center for Biological Diversity, concurred that "it's extremely concerning that over 70% of cases show that pesticides significantly harm soil invertebrates."

"Our results add to the evidence that pesticides are contributing to widespread declines of insects, like beneficial predaceous beetles, and pollinating solitary bees," she said in a statement. "These troubling findings add to the urgency of reining in pesticide use to save biodiversity."

In December, Food and Agriculture Organization (FAO) of the United Nations released a report emphasizing how vital soil organisms are to food production and battling the climate crisis—and highlighting that such creatures and the threats they face are not being paid adequate attention on a global scale.

"Soils are not only the foundation of agri-food systems and where 95% of the foods we eat is produced, but their health and biodiversity are also central to our efforts to end hunger and achieve sustainable agri-food systems," FAO Director-General Qu Dongyu said at the time, pushing for increased efforts to protect the "silent, dedicated heroes" that are soil organisms.

A growing body of research has also revealed the extent of insect loss in recent decades, with a major assessment last year showing that there has been a nearly 25% decrease of land-dwelling bugs like ants, butterflies, and grasshoppers over the past 30 years. The experts behind that analysis pointed to not only pesticides but also habitat loss and light pollution.

In January, a collection of scientific papers warned that "insects are suffering from 'death by a thousand cuts,'" and called on policymakers around the world to urgently address the issue. That call followed a roadmap released the previous January by 73 scientists outlining what steps are needed to tackle the "insect apocalypse."

The roadmap's key recommendations included curbing planet-heating emissions; limiting light, water, and noise pollution; preventing the introduction of invasive and alien species; and cutting back on the use of synthetic pesticides and fertilizers.

"We know that farming practices such as cover cropping and composting build healthy soil ecosystems and reduce the need for pesticides in the first place," Aditi Dubey of University of Maryland, who co-authored the new study, said Tuesday. "However, our farm policies continue to prop up a pesticide-intensive food system."

"Our results highlight the need for policies that support farmers to adopt ecological farming methods that help biodiversity flourish both in the soil and above ground," Dubey declared. 

While the solutions are clear, according to the researchers, the chemical industry is standing in the way.

"Pesticide companies are continually trying to greenwash their products, arguing for the use of pesticides in 'regenerative' or 'climate-smart' agriculture," said co-author Kendra Klein, a senior scientist at Friends of the Earth. "This research shatters that notion and demonstrates that pesticide reduction must be a key part of combating climate change in agriculture."