How antibiotic-filled stool helps "bessbug" beetles stay healthy

The horned Passalus beetle, commonly known as the Baysburg beetle or Betsy beetle, has a way of life that may make ordinary people feel downright disgusting: this shiny black beetle eats its own feces, but it uses feces to arrange it.

Although it looks disgusting, a new study shows that the frass habit of this beetle is actually part of a smart strategy to protect insect health and may help inform human medicine, researchers at the University of California, Berkeley It has also been found that the horned Passarus beetle contains a large amount of antibiotics and antifungal chemicals in its body, similar to the chemicals used by humans to resist bacterial and fungal infections

"Most antibiotics and antifungal drugs taken by humans are actually made of microorganisms," said Matthew Traxler, senior author of the research report and assistant professor of plant and microbial biology at the University of California, Berkeley: How to use these molecules in the environment is very interesting

With this discovery, bessbug beetles have joined other insects, including leaf-cutting ants, southern pine beetles and bee wolves, or bee killer wasps, thanks to their symbiotic relationship with actinomycetes

No special structure that hides bacteria has been found in the Baysburg beetle, but this may be the advantage of this beetle

"We collected samples from galleries in the southern and eastern United States, and almost all galleries, we can detect some form of antibiotics

The diversity of antibiotics and antifungal compounds work together.

Traxler and Pessotti are looking for a way to study wild actinomycete bacteria and learned that actinomycetes have been found to live in the internal organs of tropical beetles that are closely related to bessbug beetles

"I collected samples from the beetles and their galleries.

This Streptomyces is not unique to Ceja Navarro beetles

Sure enough, the Oklahoma beetle hides the familiar Streptomyces species

Pesotti spent a month crisscrossing the southeastern United States, trekking in the forest looking for beetle galleries, collecting samples and taking them back to Berkeley's laboratory

In addition to managing logistical challenges, such as rearranging the itinerary at the last minute to avoid Hurricane Florence, Pesotti must also teach herself how to spot the beetle galleries in the gravel at the bottom of the forest

She quickly learned that the key to finding the Baysburg Beetle Gallery is, Pesotti said: "You don't need to go far in the forest to find the Beetle Gallery-I actually found some near the trails

For the protection of feces in the laboratory, Pessotti isolated more than 300 strains of actinomycetes from her gallery samples, and detected antifungal and antibiotic compounds in all but one of the actinomycetes

With the help of Jewel Reaso, a former undergraduate at the University of California, Berkeley, Pesotti also designed a special experiment to confirm that actinomycetes do help protect beetles from infection

"I was very lucky.
During this trip, I found a dead beetle lying on a piece of wood-like a beetle waiting for me
.
Pesotti said: "This dead beetle has a white/green color on its body.
The substance, I think it may be some kind of fungus
.
"So, I took this dead beetle to the laboratory and isolated the green/white substance microbes.
It turned out that it was a strain of Metarhizium anisopliae, a fungal pathogen that can kill insects
.
"

Pessotti's experiments show that sterile bacteria mixed with Streptomyces are more resistant to the growth of Metarhizium anisopliae than individual sterile bacteria, even under warm and humid conditions similar to rotting logs
.
Her findings confirmed that the antibiotics and antifungal molecules produced by actinomycetes can actually help protect against beetle pathogens found in the wild
.

The results of this study provide new clues to the close relationship between the Baysburg beetles and their feces: When the beetles use Frass to draw lines on their corridors and build protection chambers around the developing larvae, they are actually in Protect yourself from fungal and bacterial pathogens, which might otherwise thrive in the rotting logs on which they built their homes
.
When the beetles eat their own food and feed it to their cubs, they are making sure that these bacteria can stick around and benefit the new generation
.

Traxler plans to continue studying the microbial communities associated with the Beetle Gallery to better understand both

Journal Reference :

1. Rita de Cassia Pessotti, Bridget L Hansen, Jewel N Reaso, Javier A Ceja-Navarro, Laila El-Hifnawi, Eoin L Brodie, Matthew F Traxler.
   Multiple lineages of Streptomyces produce antimicrobials within passalid beetle galleries across eastern North America .
   ELife , 2021 ; 10 DOI: 10.
   7554/eLife.
   65091