Moose Drool Undermines Toxic Fungus in Plants

As moose feed, their slobber may weaken the toxic defenses of certain grasses, displaying the power of drool, according to a report in the journal Biology Letters.

Some tasty grasses harbor fungi such as Epichloë festcuae, which can produce strong alkaloid toxins. These compounds can make large grazing animals sick and potentially cause loss of limb.

Yet herbivores like moose and reindeer have developed an unconventional way of fighting back, according to ecologist and lead study author Andrew Tanentzap of the University of Cambridge: they drool.

"Herbivores can actually fight back," Tanentzap told Zoologger. "No one has ever thought of this."

In the study, researchers simulated grazing by clipping red fescue, a common grass that is a major part of the animals' diet, and dabbing it with moose or reindeer salvia. The research team found that when applied to grasses two or four times, their spit could lower the concentrations of the toxin ergovaline by 40 to 70 percent over the course of two months. Not to mention, that dripping the drool on Epichloë in lab dishes slowed down fungal growth.

"The exact mechanism of ergovaline suppression is unknown," the researchers told the The Royal Society of London, but the results indicate that herbivore saliva interferes with the signaling which switches on a plant's defense mechanism and alkaloid production.

While it's impressive that herbivores like moose can actually fight back and slow down the growth of the fungus itself, Tanentzap told Zoologger that it's less surprising because many animals' saliva has antifungal properties - including human saliva.

"If these animals continually graze the same plants, then it would be quite beneficial," added Gary Felton of Penn State University in University Park, Penn. "We are still uncovering novel roles for saliva," he said.

For instance, sheep saliva can even stimulate plants to grow, according to a related study published in 2012 in the journal PLOS ONE.