A belly full of wriggling worms makes wood beetles better recyclers

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Having hundreds of roundworms living inside your abdomen may seem like a bad thing. But for horned passalus beetles, hosting wriggly nematode larvae may benefit them and the eastern U.S. forests they live in.

Beetles that harbor Chondronema passali larvae eat more rotting wood than beetles without the larvae, researchers report May 1 in Biology Letters. That increased decomposition could speed the cycling of forest nutrients, the authors suggest.

Earlier research found that about 70 to 90 percent of Odontotaenius disjunctus, commonly called bess beetles or patent leather beetles, are inhabited by hundreds if not thousands of nematodes, but appear to suffer few ill effects. The larvae feed off the beetles haemolymph, the insect version of blood, and in doing so suck up some of the beetles available energy, an effect thats noticeable only when the beetles are under short-term stress.

That increased need for energy could be what drives infected beetles to chomp more wood, says Andy Davis, an ecologist at the University of Georgia in Athens. Its also possible that beetles with larger appetites have more opportunities to become infected since they eat more wood, he says.

Davis and undergraduate student Cody Prouty captured 113 beetles from the woods near campus and isolated each one in a container with a chunk of wood. “On a quiet day, you could go in the lab and hear them chewing,” Prouty says.

After three months, the team weighed how much wood each insect had eaten, digested, excreted and eaten again after letting bacteria and fungi break the pulp down more. The researchers then dissected the beetles to identify which had nematodes. Beetles with nematodes had processed an average of 0.77 grams of wood per day. That was about 15 percent more than uninfected beetles, which averaged 0.67 grams per day. Beetles with nematodes were also were slightly larger, on average, something that could contribute to their larger appetites.

Davis says hed like to measure the eating habits of the beetles before and after acquiring nematode larvae, and find out the impact of having different amounts of larvae in the gut. But first scientists need to figure out how and when the nematodes get into the beetles in the first placRead More – Source

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