Bedbugs are notoriously difficult to kill. Human-created pesticides often fail to conquer the evasive bloodsuckers, but could a new chemical gleaned from the bugs themselves help?
Adding synthetic versions of the compound—a bedbug alarm pheromone—to a common nontoxic pest control agent nearly doubles the speed with which the agent kills, according to a study published last week in the Journal of Medical Entomology. Unlike their more attractive sex-drive chemical counterparts, natural alarm chemicals cause insects to scatter—in this case, right through a deadly dehydrating dust.
Fifty years after DDT largely eradicated the mini critters from developed countries, bedbugs are biting again. And this potent insecticide is no longer an option. The U.S. Environmental Protection Agency (EPA) banned nearly all uses in 1972 after concerns over its toxicity to humans and wildlife.
The EPA in April held its first-ever National Bedbug Summit, and in May the Don't Let the Bedbugs Bite Act of 2009 was introduced in Congress by representatives from North Carolina, Florida, Texas and Alaska. According to the bill's findings, "bedbug populations in the United States have increased by 500 percent in the past few years." And urban areas tend to be the hardest hit: More than 22,000 New Yorkers made bedbug-related calls to the city's help line in 2008, up from just over 10,500 in 2006. "Bedbugs are horrific. People call desperately crying," says New York City Council Member, Gail Brewer, who has helped launch the city's new Bedbug Advisory Board. "Everything we can come up with could help."
Desiccant dusts, which are also used to eradicate fleas, ticks and cockroaches, scratch up an insect's protective outer layer, causing their bodies to dry out. This result relies on them actually walking through the finely ground powder that is typically applied in cracks, crevices or the interior of a bed frame. Bedbugs, however, are generally lazy, congregating in tiny spaces for extended periods of time. "With the alarm pheromone, they get agitated and start running through this material," says Joshua Benoit, lead author of the study and a member of the Central Ohio Bed Bug Task Force.
In the study Benoit, a doctoral candidate in entomology at The Ohio State University in Columbus, and his colleagues tested combinations of desiccant dust and two bedbug alarm pheromone chemicals, first with the poppy seed–size bugs in petri dishes and then in a larger plastic container with a folded piece of paper. The latter test represented a more lifelike situation by offering the bedbugs a place to hide. In the end the most lethal potion included both pheromone components and the dust. Compared with the dust alone, the combination significantly sped up water loss and cut the time it took to kill the bugs by half. "If it normally takes the bugs one day to die," Benoit says, "they will die within 12 hours."
Although his results are encouraging, Benoit is clear the pheromones are not yet ready for the night shift. "I don't encourage people to start throwing these alarm pheromones all over the place," he says; the chemical components are not even available in the appropriate concentrations if someone wanted to mix their own, according to Benoit. (In any case, he notes the eventual price tag of the potion would be "minimal" given that only "minute" concentrations of the pheromone would be needed.) Benoit's main concern is that the alarm response could drive bedbugs into adjacent areas, simply spreading the problem. He suggests future tests in real apartment environments to ensure this doesn't happen.
Jocelyn Millar, who studies insect pheromones at the University of California, Riverside, likes the new approach. "It's a different way than just spraying toxic insecticides around," he says. Millar is concerned, however, about the "level of control"—the only treatment that will really work is one that kills 100 percent of the bedbugs—as well as with the alarm compound's pungent odor. "If you go into a hotel room that's been treated," he says, "you wouldn't be happy."
Benoit acknowledges the dire current situation in bedbug extermination. "The main problem is nothing is working. Or if it is working, it only works for awhile and then the bedbugs become resistant," he says. One of Benoit's colleagues, who is on the Central Ohio Bedbugs Task Force, tells him, "They are pretty much open to anything at this point."