The study appears in the June 2012 issue of the Journal of Economic Entomology http://entsoc.blogspot.com/, 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 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 numbers have increased in the past decade as much as 500% in North America and other parts of the world. Ohio University researchers say a spike 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 the insects and how easily they spread; and the development of resistance among bedbug populations to currently used pesticides, especially pyrethroids are all to blame for the boom.

In the study, researchers evaluated three different fogger brands obtained from a nationwide retailer, all of which have pyrethroids as their active ingredient. Only one of the foggers was specifically labeled against bedbugs, the other two were labeled for use against flying and crawling pests in homes, but can be used to treat bedbugs in many states.

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, researchers say they 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 layer that provided shelter.

Because a majority of bedbugs spend most of the time hiding in protected sites, researchers say 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, they say 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.”