Eco-briefs | New bacterium explains symbiosis with insects

Colin Dale with a bacterial culture
Photo courtesy of Lee Siegel, University of Utah


After a 71-year-old Indiana resident impaled his hand on a dead crab apple tree branch two years ago, it became infected with a previously unknown strain of bacterium — and the discovery has scientists linking the pieces to better understand symbiotic relationships between bacteria and insects in ways that could help slow insect-transmitted diseases.

“Symbiotic interactions between microorganisms and insects are common, and biologists suspect that they’re an important driver of biological diversification,” says Matt Kane, program director in the National Science Foundation’s Division of Environmental Biology, according to an NSF press release. “But how such symbioses came to be is often a mystery.”

Once established, symbiotic relationships between insects and bacteria provide bacteria with shelter and nutrition, and provide insects with B vitamins, amino acids and sometimes toxins to kill invaders.

The findings provide “a missing link in our understanding of how beneficial insect-bacteria relationships originate,” says Colin Dale, a researcher at the University of Utah who discovered Sodalis, a genus of bacteria that lives in insect guts in a symbiotic relationship, which is related to the new strain human Sodalis, or HS. “They show that these relationships arise independently in each insect. The insect picks up a pathogen that is widespread in the environment and then domesticates it.”

The mother then passes the bacteria on to her offspring, he says.

With genetic alterations to this new bacterium, researchers say, they could prevent insects from transmitting diseases to humans or crops.


The Peñasco least chipmunk, native to New Mexico, and the Cumberland arrow darter, which lives in Kentucky and Tennessee, are the two species added to the list of candidates for protection under the Endangered Species Act, according to a U.S. Fish and Wildlife Service press release.

The U.S. Fish and Wildlife Service’s annual Candidate Notice of Review updates the status of plant and animal candidates for protection under the Environmental Protection Act. This year’s list includes 192 species, a 12-year low for the list.

Christ’s paintbrush | Photo courtesy of Gina Glenne, US Fish & Wildlife Service

In addition to the two additions, three species were removed and nine changed in priority. Following successful conservation efforts, the elongate mud meadows springsnail and Christ’s paintbrush were removed from the list this year, as was the bog asphodel, after site protections and the identification of additional sites.

But the drop in number of species listed is largely attributed to a court-approved work plan that resolved a series of lawsuits and reduced the workload on litigation-related tasks.

“We’re continuing to keep the commitments we made under this agreement, which has enabled us to be more efficient and effective in both protecting species under the ESA, as well as in working with our partners to recover species and get them off the list as soon as possible,” says Dan Ashe, Fish and Wildlife Service director, according to a press release. “Our ultimate goal is to have the smallest Candidate List possible, by addressing the needs of species before they require [Endangered Species Act] protection and extending the ESA’s protections to species that truly need it.”

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