Bedbugs not averse to inbreeding
Pests have also grown resistant to common insecticides
By Nathan Seppa
PHILADELPHIA — Bedbugs that infest a room and spread within a building are often one big extended family, the offspring of a single female that begot sons and daughters that then interbred with impunity, researchers reported December 6 at a meeting of the American Society of Tropical Medicine and Hygiene.
Other scientists at the meeting reported on mechanisms that allow bedbugs to escape death by rapidly evolving to detoxify insecticides thrown their way. In that study, the researchers identified enzymes that the insects need in this detoxification process.
Cimex lectularius, the bedbug, has become a scourge of slum tenements and upscale hotels alike in the past 10 years, staging an impressive comeback after being knocked back to insignificance with insecticides in the 1950s and 1960s. But even before that there were hints of future problems, said entomologist Kenneth Haynes of the University of Kentucky. The first reports of the insecticide DDT failing to kill bedbugs surfaced in 1948, he noted.
To get a reading on the current level of resistance, Haynes and his colleagues tested 108 bedbug populations and found that 88 percent had one or two genetic mutations associated with resistance to either DDT or pyrethroids, a widely used family of pesticides. “Pyrethroid resistance has facilitated in part the resurgence and/or spread of bedbugs,” Haynes said. The group traced this resistance to genetic changes that enabled the bugs to produce enzymes that detoxify insecticides. To establish this, the researchers shut down the enzymes’ production, which rendered the bugs vulnerable to deltamethrin, a synthetic pyrethroid.