Editor's Note: The following article appeared on Mike Merchant's blog, "Insects in the City," which can be found at http://insectsinthecity.blogspot.com. The blog offers readers news and commentary about the urban pest management industry and is excerpted here with permission of the author.
This past spring I had the opportunity to visit with scientists at Research Associates Labs in Addison, Texas. They told me about a new application of DNA fingerprinting that, I believe, has some exciting uses in the pest control industry.
In July I had the chance to catch up again with one of Research Associates' scientists, Dr. Kate Johnson, who was explaining the service to PMPs attending the first-ever Bed Bug Academy of the Southwest sponsored by the Texas Pest Control Association.
This meeting was Research Associates' Labs first introduction to the pest control industry. Until recently, the firm's focus was on providing molecular diagnostics tests to vets and zoos. The techniques that Dr. Johnson describes may seem like cutting edge stuff to us in pest control, but the technology is not especially new. Using a 20+ year-old technique known as real-time PCR, DNA collected on a swab can be rapidly amplified so that it can be detected by laboratory equipment, much like a stereo receiver amplifies otherwise inaudible radio waves.
How it Works. The key to pest detection is finding a piece of DNA that is unique to the target organism you wish to detect. Once this DNA fragment is identified, special primers can be selected that will amplify only the target DNA strands. If the unique DNA is not present, nothing gets amplified and detected. Research Associates Labs has customized the technique to look specifically for bed bug DNA. Using sterile swabs, a PMP can walk into an account and quickly sample the likeliest locations in a room for bed bug DNA. Once received by the laboratory, it's only a matter of a few hours to learn whether bed bugs have been present in a room.
There are a few limitations to the procedure and how to interpret the results. First, you have to take a good sample from the right areas in a room. Second, some chemicals, including pesticides, can interfere with the results. But perhaps most importantly, the test cannot easily tell whether bed bugs are still active in a room. Because bed bug DNA lasts a long time in an indoor environment, one cannot assume that a positive test didn't come from an infestation that was eliminated a year earlier, for example.
With time, I suspect we'll see the real value of DNA testing in detecting low-level bed bug infestations in homes where visual inspections don't reveal bed bugs, but where a client insists that bites are occurring. Given the expensive nature of expanding bed bug treatment into rooms beyond a bedroom, the technique also might be useful when initially inspecting and bidding an account to determine whether additional rooms in a home might need treatment. At $15 a pop, hotels might find the service a little pricey for regular use; however, the technique might be useful in confirming a positive detection of bed bugs by a canine bed bug team doing routine hotel inspections or to confirm/disprove guests' complaints of bed bugs.
With additional tests, the DNA technique could be most helpful in confirming the absence of biting mites, fleas and bed bugs from those mystery bug clients we encounter. Although there are DNA tests for the presence of scabies, mites and cat fleas, there is not yet a kit for the common biting mites (rat, chicken or bird) that must be ruled out in mystery bug cases. Pretty soon, however, I predict that bed bugs, and perhaps all pests, will have no place to go and no place to hide.
The author has been an entomology specialist for Texas AgriLife Extension since 1989. Contact him via e-mail at firstname.lastname@example.org.
To see what Dr. Kate Johnson had to say about how the DNA fingerprinting process works, visit www.pctonline.com and click on “Online Extras” to see a video by Mike Merchant.