The lowly earthworm’s feeding and burrowing mixes in organic residues and enhances nutrient cycling, decomposition and the structural development of soil. But rampant pesticide use threatens the existence of these crucial invertebrates, according to a new study.
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Researchers at the University of Maryland, Friends of the Earth U.S. and the Center for Biological Diversity were involved in what they’re calling “the largest, most comprehensive review of the impacts of agricultural pesticides on soil organisms ever conducted.” The journal published the study on Tuesday.
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“Below the surface of fields covered with monoculture crops of corn and soybeans, pesticides are destroying the very foundations of the web of life,” study co-author Nathan Donley said in a statement. Donley is a scientist at the Center for Biological Diversity. “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. Yet our regulators have been ignoring the harm to these important ecosystems for decades.”
The researchers reviewed almost 400 other studies on how pesticides affect non-target invertebrates that develop in the soil for at least part of their lifespan. These include beetles, ants, earthworms and ground-nesting bees. They considered how 284 different pesticide ingredients affected 275 unique invertebrate species.
The scientists’ conclusions were startling. More than 70% of the study’s tested parameters showed negative effects. Only 1.4% found positive effects. The rest indicated no significant effects from pesticide exposure.
The results surprised Donley, who didn’t realize the damage went so deep. “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.”
The damage to soil-dwelling invertebrates is part of a bigger trend some scientists have dubbed “the bugpocalypse.” A study last year put the number at a 25% decrease in terrestrial bugs, like grasshoppers and ants, over the last three decades. Light pollution and habitat loss also led to the bugs’ demise in addition to pesticide use.
+ Frontiers in Environmental Science