Bed Bugs Resist Pesticides

A bed bug feeding on a human.

(Image credit: Armed Forces Pest Management Board)

Bed bugs are back, as many urbanites know. And while exterminators usually can eliminate bed bugs, a study shows that some of the pesky insects are developing resistance to pesticides.

Bed bugs feed on human blood.

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The mutations affect sodium channels (resembling pores) in the neurons' outer membrane, where electrical nerve impulses are produced. In the past, these nervous system poisons could effectively paralyze and kill the bugs, but this is no longer always the case. Using molecular techniques, the researchers sequenced genes related to the sodium ion channel's operation in both groups and identified two mutations found only in the resistant population. Similar mutations have been found in other pyrethroid-resistant insects and are likely the cause of the resistance in bed bugs, Clark and colleagues said.

Also, most pest control companies rely on more than one insecticide to combat bed bugs, he said. The ideal is to use a combination of chemicals that have different modes of action — perhaps one is good at killing the adults and nymphal stages immediately while another is better at lingering and killing bugs days later — and come from different chemical families, not just pyrethroids, Sorkin said. Exterminators also have different ways to administer insecticides, which can make a difference — foams, powders, aerosols. However, over-the-counter aerosol bombs are not recommended. They just cause the bugs to scatter, Sorkin said, and fail to get inside cracks where bugs can hide. "Some people don't like to say they have bed bugs. They try to take care of it themselves,” Sorkin said. But amateur attempts often just push the bugs away for a while and spread them into neighboring properties. Many urban dwellers like to "trash pick," or go through the furniture and clothes that are left out on the curb before they are taken away by the garbage service. But nowadays, some of that furniture was put out as trash because it came from a home infected with bed bugs. "People think, 'That's a nice piece of furniture,' and take it home. They get a bargain. The bed bugs are free, but controlling them is expensive," Sorkin said. Integrated pest management The state of the art in extermination is integrated pest management, Sorkin said, which means a multi-pronged attack that goes beyond spraying or misting insecticides.

Techniques include caulking, spackling and using other sealants to fill cracks and crevices, refinishing and sealing floors, injecting frozen carbon dioxide "snow" into electronics to freeze pests, re-painting walls and other surfaces, using low-moisture steam and clothes dryer heat to kill bugs, and injecting bug-killing dust into electrical outlets and switches. Sorkin and others recently collaborated with Jody Gangloff-Kaufmann and Cathy Pichler of the New York State IPM Program at Cornell University on an integrated pest management plan for homeless shelters in New York, which are susceptible to bed bugs. "A lot of exterminations work because not all the populations here are resistant," Sorkin said. There are 400 products registered in New York for bed bug control, he said, although many of them are made of the same chemicals in different strengths, ratios and preparations. There is even one company in Queens, New York, that works with moving companies for a total isolation approach for tough cases. Specially trained movers pack up your apartment and seal everything in plastic, Sorkin said, before taking everything to the company's fumigation center. Packages are opened and sealed up in an environment filled with toxic gas. Meanwhile, the empty apartment is also vacuumed and treated, and clothing is isolated and bagged. "People have a lot of clutter in their apartments, but the more things are isolated, the better," Sorkin said.

Robin Lloyd was a senior editor at Space.com and Live Science from 2007 to 2009. She holds a B.A. degree in sociology from Smith College and a Ph.D. and M.A. degree in sociology from the University of California at Santa Barbara. She is currently a freelance science writer based in New York City and a contributing editor at Scientific American, as well as an adjunct professor at New York University's Science, Health and Environmental Reporting Program.