Volume 93 Issue 21 | p. 9 | News of The Week
Issue Date: May 25, 2015 | Web Date: May 21, 2015

Snow Fleas Pack A Chemical Weapon

Chemical Ecology: Cold-weather-loving insect produces never-before-seen chlorinated natural product to deter predators
Department: Science & Technology | Collection: Critter Chemistry, Life Sciences
News Channels: Biological SCENE, Environmental SCENE, Organic SCENE
Keywords: snow fleas, critter chemistry, insecticides
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Credit: F. Kohl
Snow fleas in a row.
 
Credit: F. Kohl

It’s easy to overlook the snow flea: The millimeter-long insect could be mistaken for a flake of pepper on a white wintery landscape. But the little organism packs some powerful chemistry. Researchers led by Stefan Schulz at the Technical University of Braunschweig, in Germany, report that the snow flea, or Ceratophysella sigillata, produces polychlorinated compounds to repel predators (Angew. Chem. Int. Ed. 2015, DOI: 10.1002/anie.201501719). The family of defense compounds, including sigillin A, is unique in that it is a new class of natural products that features a chemical scaffold that could find application in insect control.

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Snow fleas love to party en masse and binge on the algae that grow on decomposing leaves.
Credit: F. Kohl
Photo of snow fleas!
 
Snow fleas love to party en masse and binge on the algae that grow on decomposing leaves.
Credit: F. Kohl

“It’s a very surprising discovery,” comments John A. Pickett, a chemical ecologist at Rothamsted Research Station, in Harpenden, England. It’s not often that scientists find any halogens in natural products made by terrestrial organisms, he says. And “here, there’s not just one chlorine, but five chlorines.”

Despite its diminutive size, the snow flea, also called a springtail, has garnered an online fan base for some of the charming strategies it uses to evade predators: In threatening situations, the insect ejects a springing device out of its rear end to propel itself to safety. The insect also likes a party: In late winter or early spring, these bugs sometimes form huge colonies, as wide as a yard, with millions of individuals migrating together like a superorganism, devouring the algae that grow on wet, decomposing leaf litter in the melting snow, Schulz explains. Sigillin A likely helps deter predators such as spiders, centipedes, and mites from feasting on the partygoers.

Snow fleas produce a rather large amount of sigillin A—about 0.2% of their body weight—which is unusual for a natural product, especially one that “is so metabolically expensive to produce,” given its chlorine content and complicated scaffold, Pickett adds. Schulz’s team also developed a protocol for synthesizing sigillin A’s basic scaffold. The seven-step process doesn’t have a high yield, but it is enantioselective and should allow chemists to produce a variety of analogs. Analogs—if potent enough—that could find use as ant deterrents, Schulz says.

Next up, Schulz and his team will study how the snow flea produces sigillin A. The natural product might be made using the snow flea’s biosynthetic machinery. Or it might be made by a symbiotic microorganism living in or on the snow flea, perhaps by polyketide synthesis, Schulz says. Another possibility is that the insect acquires the unusual compound through its food supply and stores it for later use.

 
Chemical & Engineering News
ISSN 0009-2347
Copyright © American Chemical Society
Comments
Brad Bond (Wed May 27 14:42:28 EDT 2015)
Let's hope our birds don't eat a lot of these. They could make very thin egg-shells.

Istvan Ujvary (Fri May 29 01:53:17 EDT 2015)
This is a very elegant work both from an analytical and (bio)synthetic points of view. The presence of trichloromethyl groups in these subtances is intriguing indeed. I have not had a chance to read the full paper so wonder whether the researchers analysed the leaves the ants were feeding on. It is not inconceivable that the substance or its precursor(s) are present in the plant material. The halogenation could thus happen not by radical chlorination in/by the fleas but in fact from a chlorinated chemical of anthropogen origin (environmental contaminant?). This "semi-natural product" is taken up from the air or soil by the plant and biotransformed into chemicals that already contain trichloromethyl groups(s), end up in decaying leaf litter in the autumn. Alternatively, the trichloro moiety can biosynthetically be formed by microorganisms occurring in forest soil. The resulting simple or complex trihalo compounds can then make their way into the gut of the snow flea (hence the earlier observed seasonal variation of the deterrent effect of the flea exudate). The authors indicate further research on the subject and we are eagerly waiting for their results!
Congratulations!
Witali Schmidt (Mon Jun 15 15:08:08 EDT 2015)
Hello Istvan. Thank you for your nice comment. We did not analysed the algae the snow fleas are feeding on, but we mentioned in the paper that we can not exclude the fact that C. sigillata is taking the Sigillin, or precursors of Sigillin up with their food.
Istvan Ujvary (Fri May 29 01:54:33 EDT 2015)
This is a very elegant work both from an analytical and (bio)synthetic points of view. The presence of trichloromethyl groups in these subtances is intriguing indeed. I have not had a chance to read the full paper so wonder whether the researchers analysed the leaves the ants were feeding on. It is not inconceivable that the substance or its precursor(s) are present in the plant material. The halogenation could thus happen not by radical chlorination in/by the fleas but in fact from a chlorinated chemical of anthropogen origin (environmental contaminant?). This "semi-natural product" is taken up from the air or soil by the plant and biotransformed into chemicals that already contain trichloromethyl groups(s), end up in decaying leaf litter in the autumn. Alternatively, the trichloro moiety can biosynthetically be formed by microorganisms occurring in forest soil. The resulting simple or complex trihalo compounds can then make their way into the gut of the snow flea (hence the earlier observed seasonal variation of the deterrent effect of the flea exudate). The authors indicate further research on the subject and we are eagerly waiting for their results!
Congratulations!
Jeff Cooper (Sat May 30 11:01:48 EDT 2015)
Are there any plans on manufacturing this chemical? IS there a synthetic process that has been developed or are they planning on farming and harvesting the product from the snow fleas?
Sarah Everts (Mon Jun 08 05:20:17 EDT 2015)
Sarah here, the reporter for this story. To answer your question: They've developed a synthetic strategy for a component of the Sigillin A scaffold and are looking at ways to build the whole thing and/or build analogs. I don't know about any plans to farm & harvest.
Lou Sorkin (Wed Jun 17 01:16:13 EDT 2015)
Springtails, Class Collembola, are actually considered not be be insects but a separate class along with two others, the Protura and Diplura. The Hexapoda is considered by some researchers to include the orders, Collemboa, Protura, Diplura and Insecta. In any case, they are not considered to belong to the Insecta.
Peter Becker (Wed Apr 12 22:45:56 EDT 2017)
We to observed springtails grazing on C. nivalis in snow banks on the Antarctic Palmer Peninsula in spring 1970. This result was reported by E. Sutton in his Doctoral studies under Herbert C. Curl and Larry Small at Oregon State University in summer 1970 and in our expedition reports to NSF-OPP.
There are no trees there and the algae do quite well both there and in Alpine regions above 3000m. Sutton was the first to culture them from soil at 1-2C in 1969 and they grow quite nicely invitro in liquid medium with carbonate as a C source.
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