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COLUMBUS, Ohio -- Ohio State University entomologists have found that over-the-counter foggers or "bug bombs" commonly used by consumers are not effective at killing bedbugs -- providing the first scientific evidence that such products should not be recommended for control of this increasingly worrisome, bloodsucking pest.
The study appears in the June 2012 issue of the Journal of Economic Entomology, a peer-reviewed publication of the Entomological Society of America.
"There has always been this perception and feedback from the pest-management industry that over-the-counter foggers are not effective against bedbugs and might make matters worse," said Susan Jones, an urban entomologist with the university's Ohio Agricultural Research and Development Center (OARDC) and a household and structural pest specialist with Ohio State University Extension. "But up until, now there has been no published data regarding the efficacy of foggers against bedbugs."
Bedbug (Cimex lectularius) numbers have increased in the past decade as much as 500 percent in North America and other parts of the world. Reasons behind this spike include a boom in international travel and commerce; a shift from powerful but dangerous insecticides, such as DDT, to more selective control tactics; the public's lack of awareness about these insects and how easily they spread; and the development of resistance among bedbug populations to currently used pesticides, especially pyrethroids.
In the study (funded entirely by OARDC and OSU Extension), Jones and research associate Joshua Bryant evaluated three different fogger brands obtained from a nationwide retailer, all of which have pyrethroids as their active ingredient. Only one of the foggers is specifically labeled against bedbugs. The other two are labeled for use against flying and crawling pests in homes, but can be used to treat bedbugs in many states, Jones said.
Experiments were conducted in three rooms in a vacant office building on Ohio State's Columbus campus. The researchers used five different bedbug populations collected from homes in Columbus between 2010 and 2011. Additionally, they included the Harlan strain -- which has been laboratory-raised since 1973 and is susceptible to pyrethroids -- as a control.
Following application of the three foggers, Jones and Bryant found little, if any, adverse effects on the five field-collected bedbug populations. One exception was what researchers call the EPM population, which showed significant mortality five to seven days after treatment but only when bedbugs were out in the open and directly exposed to the insecticide mist. Pyrethroid-susceptible Harlan bedbugs experienced high mortality when out in the open, but were not affected when covered by a thin cloth of layer that provided shelter.
Because a majority of bedbugs spend most of the time hiding in protected sites (under sheets and mattresses, in cracks and crevices, deep inside carpets, etc.), Jones said it is very unlikely that they will be exposed to the insecticide mist from foggers. And even if they come into contact with the mist, she added, many bedbug populations found in Ohio and throughout the U.S. have varying degrees of resistance to pyrethroids and will most likely survive application.
"The nature of these foggers is such that they don't penetrate in cracks and crevices where most bedbugs are hiding, so most of them will survive," Jones said. "If you use these products, you will not get the infestation under control, you will waste your money, and you will delay effective treatment of your infestation. Bedbugs are among the most difficult and expensive urban pests to control. It typically takes a professional to do it right."
Jones said she will submit the data from this study to the Environmental Protection Agency so officials there can look into the labeling of foggers that indicate they are effective against bedbugs. "Each one of the three foggers we studied claims 'kills on contact' on the label," she pointed out. "The public is ill-served when products do not perform in accordance with labeling. Also, the ineffective use of these products can lead to further resistance in insects."
For more information about bedbugs, including an identification guide, management options and tips for hiring a pest-management company, see the OSU Extension fact sheet on bedbugs at http://ohioline.osu.edu/hyg-fact/2000/2105.html or download the fact sheet on Choosing a Pest Management Company at http://ohioline.osu.edu/hyg-fact/2000/pdf/2178.pdf.
OARDC and OSU Extension are the research and outreach arms, respectively, of Ohio State's College of Food, Agricultural, and Environmental Sciences.