Southern pine beetles, a new source for antibiotics

Experts are welcoming a study that suggests the pine beetles devastating large tracts of North American forests could be a treasure trove of new antibiotics. Researchers from the University of Wisconsin-Madison and Harvard Medical School have isolated a new antibiotic compound in the bacterium associated with the southern pine beetle, a close relative of British Columbia's mountain pine beetle. The finding could yield "intriguing possibilities" in the medical field, said Dezene Huber, Canada Research Chair in forest entomology at the University of Northern B.C. "The idea is if we start looking at some of the microbes associated with insects, it could lead to a new drug that can selectively kill fungi or bacteria," said Huber.

"That's a fantastic thing. It could potentially benefit people." The pine beetle is associated with a beneficial fungus that burrows underneath tree bark and provides food for the beetle's larvae. But hitchhiking mites attached to the beetle's shell bring along their own fungus that competes with the beetle fungus for nutrients in trees, much like a "weed in the beetle's fungal garden," said Cameron Currie, evolutionary biologist at the University of Wisconsin-Madison and co-author of the study, published last week in the journal Science.

Coming to the rescue is a bacterium also carried by beetles that wields an antibiotic compound called mycangimycin, which protects the insect's fungus by inhibiting the growth of the enemy fungus. It is still unknown whether the antibiotic compound has any application for human medicine, said Currie, an Edmonton native. But the implications of a new possible source of antibiotics are promising, especially at a time when soil-sourced antibiotic compounds are being exhausted and resistance to existing antibiotics is rapidly increasing.

The southern pine beetle is the third type of insect -- after leaf-cutting ants and European beewolf wasps -- to be associated with antibiotic-wielding bacteria. The potential health boon might come as little consolation to B.C. communities ravaged by the marauding mountain pine beetle, which devoured 13.5 million hectares of pine stands last year. The fact that the pests might be a medical wonder is merely "biological reality," said Huber. "If it has a bacteria that produces antibiotics that might be useful, then great," he said. "It's not related per se to the damage going on in the woods."

The scientific finding could also be helpful in managing the pests, said Currie, who began similar research on the mountain pine beetle in September.

"Anytime there is a better understanding of these complex interactions, it sheds light on the dynamics of the pests. . . (and) that can include managing outbreaks." Source: The StarPhoenix.