We’re Losing The Arms Race Against Bed Bugs

The blood suckers are learning to resist more and more insecticides

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Apr 10, 2017 at 4:00 PM ET

After decades of dormancy, the blood-sucking human bed bug (Cimex lectularius) has made an unwelcome return back into our real-life nightmares since the turn of the century. That resurgence has largely been thanks to the bug’s increasing ability to survive the insecticides we use to control them. And the problem may be even worse than we thought, according to a new study published Monday in the Journal of Economic Entomology.

Researchers at Purdue University exposed ten different populations of bed bugs, collected from across the country in recent years, to the insecticides chlorfenapyr and bifenthrin. They found that half showed signs of varying resistance to chlorfenapyr, while a third showed the same for bifenthrin. The findings, which are the first to measure chlorfenapyr and bifenthrin resistance on a large scale according to the researchers, only add to the laundry list of insecticides bed bugs have been shown to fend off.

Chlorfenapyr and bifenthrin belong to a class of insecticides known as pyrethroids. Pyrethroids, along with their naturally-found cousins pyrethrins, have become the go-to tool for household bug control since DDT was largely phased out in the 1970s worldwide, thanks to their relative harmlessness to people and the environment. For a brief moment, they helped make the bed bug virtually extinct within the developed world. But much like with antibiotics, our overconfidence has come back to bite us— hundreds of insect species, from mosquitoes to bed bugs, have steadily adapted over the decades, developing and passing on new mutations that can neutralize the chemicals.

Bed bugs in particular are almost impervious to the popular pyrethroid called deltamethrin nowadays, studies have shown, but there’s been less work done in examining resistance to other classes of this chemical.

In the current study, the research team found something else troubling. Despite chlorfenapyr and bifenthrin attacking bed bugs differently, strains resistant to one were more likely to resist the other as well. That suggests bed bugs have developed mutations that can broadly protect against a variety of chemicals at once, such as thicker, tougher skin, or a cuticle as it’s called in the insect world. Already, there’s evidence that bed bugs are learning to resist newer classes of insecticides using these strategies.

Not all hope is lost though in our long-standing war against the bed bug — provided we can be craftier about how to fight them.

“There is a plethora of research that has shown that if insecticides are integrated with additional control measures such as vacuuming, steam or heat, mattress encasements, traps, and desiccant dusts, effective bed bug control can be accomplished and theoretically this should reduce the risk of resistance build-up in populations,” said senior author Ameya Gondhalekar, an entomologist at Purdue’s Center for Urban and Industrial Pest Management, in a statement.