“Many of the insects and invertebrates that are in decline have life phases in the soil. “When people talk about insect decline, they rarely talk about the soil,” says Nico Eisenhauer, a soil ecologist at Leipzig University in Germany and one of the authors of the new study. But this new study is part of a growing body of research suggesting that at least in the forests of northern North America, earthworms may not be the slimy angels of the underworld we tend to think they are. Worms earned their reputation by aerating and mixing soil with their burrows and releasing locked up nutrients in their castings, all of which can help certain plants thrive.

These results might sound surprising, since earthworms are widely considered to be helpful garden residents.

The study looked at 60 plots in an aspen and poplar forest in Alberta, Canada, and found that as the numbers of earthworms wriggling in the soil and leaf litter increased, the diversity and abundance of invertebrates aboveground decreased.

As for the how and why of these declines, the prime culprits are habitat destruction, rampant use of pesticides, and climate change.īut new research published March 30 in Biology Letters adds an unexpected suspect, at least for a large swath of North America: the earthworm. In the past five years, reports of staggering insect declines have stoked anxiety and debate concerning the fate of the “little things that run the world,” as the late biologist E.

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