Other side of the sheets: NMR battles bedbugs

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  • Published: Jan 8, 2015
  • Author: David Bradley
  • Channels: NMR Knowledge Base
thumbnail image: Other side of the sheets: NMR battles bedbugs

Nighty night

Bedbug research - Simon Fraser University chemist Robert Britton (left) and biologists Gerhard Gries and Regine Gries have cornered and put to bed the pheromone structure

Nuclear magnetic resonance (NMR) spectroscopy has outstripped gas-chromatography mass spectrometry in the search for an important pheromone of the increasingly common pest, the bedbug (Cimex lectularius). The long-anticipated identification of the creature's aggregation pheromone by a team in Canada offers hope of developing a way to smother the resurgence of this worrying nocturnal adversary.

Biologists Regine Gries and Gerhard Gries of Simon Fraser University in Burnaby , Canada, and their colleagues have spent the last eight years or so searching for a way to conquer a global epidemic and it's blood from Regine's arm that has been crucial to their mission. Working alongside chemist Robert Britton and their students, the researchers fed bedbugs Regine's blood to help them find the chemical attractants, the pheromones, that cause bedbugs to aggregate. Ultimately, one of these pheromones or a synthetic analogue might provide the chemical lure for a trap to capture the pest.

Indeed, the team has carried out a series of successful trials in bedbug-infested apartments in Metro Vancouver, working with Victoria-based Contech Enterprises Inc. to develop the first effective and affordable bait and trap for detecting and monitoring bedbug infestations. The product should be on the market within a year.

Biting parasites excite

Bedbugs are parasites that feed exclusively on blood and while commonly active at night they are not nocturnal exclusively. They feed on human blood, usually without the victim even noticing, but their activity subsequently can cause very itchy and inflamed skin rashes and allergies, something that Gerhard but crucially not Regine knows only too well from personal experience. They were not considered to be disease vectors until very recently when it was found that they can transmit the pathogenic protozoan, Trypanosoma cruzi, which causes Chagas disease, a disease found in Central and South America and known as American trypanosomiasis.

They were all but eradicated in the developed world during the 1940s, but numbers have risen again since the mid-1990s and are being found not only in low-income housing but also in the classiest of hotels and apartments. They are also appearing in theatres, libraries and on buses and trains. Their ability to act as a vector for a Tropical disease makes the childhood axiom of "good night, sleep tight, don't let the bedbugs bite" a little more urgent a warning than it perhaps once was. Finding inexpensive and easy to use tools for the detection and monitoring of this pest is now a priority.

"The biggest challenge in dealing with bedbugs is to detect the infestation at an early stage,” explains Gerhard. "This trap will help landlords, tenants, and pest-control professionals determine whether premises have a bedbug problem, so that they can treat it quickly. It will also be useful for monitoring the treatment's effectiveness."

Gerhard is a pioneer in the field of chemical and bioacoustic communication between insects and with Regine running all of the laboratory and field experiments for the last eight years the team has closed in on a solution. Interestingly, Regine's dedication to the cause and immunity to the bedbug's bites meant enduring 180,000 bedbug bites in order to feed the large bedbug colony required for the research.

Initially, the team used their regular gas chromatographic and mass spectrometric tools to hunt for the elusive aggregation chemical that draws female bedbugs to males and deters other males. But, their experiments showed that while the team could attract bedbugs with an extract purportedly containing the pheromone in their laboratory experiments, it was not working in bedbug-infested apartments. "We realized that a highly unusual component must be missing," Gerhard says. At this point they teamed up with NMR expert Britton to help them isolate and solve the structure of the natural product that was evading them. Using samples of shed bedbug skin, the team gradually and with many false trails over the course of two years, homed in on the telltale spectral lines.

Histamine clue

The molecule histamine was heavily involved in controlling bedbug behaviour, the alkaloid more often thought of as being involved in inflammation and the allergic response in humans acts as a chemical signal for "safe shelter" to bedbugs. When the pest comes into contact with histamine it stays put whether or not it has recently fed on human blood.

Bizarrely, neither histamine alone nor in combination with the previously identified pheromone components effectively attracted and trapped bedbugs in infested apartments. There remained an unknown component of the chemical communication system. Regine thus began analysing the airborne volatile compounds from bedbug faeces as a possible source of this missing component, or components. Five months and 35 experiments later, she had found three new volatiles that had never before been reported for bedbugs. These three components, together with two components from their earlier research and, of course, histamine, became - in combination - the highly effective lure they were seeking.

Related Links

Angew Chem Int Ed Engl, 2015, online: "Bed Bug Aggregation Pheromone Finally Identified"

Article by David Bradley

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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