Without the lowly dung beetle, we'd be in deep doodoo, somewhat literally. As Mother Jones explains, 100 billion tons of dung are excreted by the planet's animals daily. Dung beetles eat dung (and use it to "woo girlfriends," among other things, as a zoologist explains at the Conversation), and the effect is profound. Dung beetles "can potentially do in 48 hours what would take a couple years" for nature to accomplish without them, Mother Jones quotes a Missouri livestock researcher as saying. And that's what makes a "little-noticed" 2015 study in Scientific Reports extra troubling, the magazine reports. The Spanish researchers looked at ivermectin, a human and veterinary drug that, on its face, does nothing but good: It effectively treats an infection that causes elephantiasis, prevents river blindness, and controls mites, roundworms, heartworms, and head lice.
But previous research has found 62% to 98% of the doses given to mammals end up in their dung. The researchers set out to determine "the direct effects of ivermectin on dung beetle physiology and behavior" and found beetles who ingested it saw their ability to use their antennae to detect food and "sexual or aggregation signals" compromised; they also found ivermectin can remain active in animal dung for at least a month. The implications could be serious: The study found "rates of decomposition of dung were ... 30% lower in the sites where ivermectin was used," per a press release. Countermeasures have been suggested—among them, injecting the drug and using it in cool months where the beetles aren't active —but they have limitations. (Another source of concern: this oceanic poop.)