Over the past decade, many U.S. cities have seen a new rise in infestations of the common bed bug — known scientifically as Cimex lectularius — in residences, hotel facilities and elsewhere. The phenomenon has had significant social and health consequences in densely populated cities such as New York, and the topic has seen extensive news coverage.

A 2011 study from Virginia Tech published in PLoS One, “Deep Sequencing of Pyrethroid-Resistant Bed Bugs Reveals Multiple Mechanisms of Resistance within a Single Population,” looks at this “frightening resurgence” of infestations and examines why “current chemical methods have been inadequate for controlling this pest.” The researchers collected samples of bed bugs from a group home in Richmond, Virginia, and from a laboratory strain that demonstrated resistance to certain chemicals.

The study’s findings include:

• “Due to the widespread use of DDT, bed bugs were essentially eradicated from U.S. homes and apartments by the 1950s. While DDT was initially effective for bed bug control, resistance to the cyclodienes was well-documented among different bed bug populations by 1958.” The latest attempts to fight bed bugs have employed insecticides in the pyrethroid class.
• After giving lethal doses of chemicals such as deltamethrin — common in many pesticides of all kinds — to the bed bug samples, the researchers concluded that they were “highly resistant to these insecticides.” The degree of resistance of this particular strain “suggest that pyrethroid insecticides would be largely ineffective in controlling this multi-resistant population.”
• Testing indicates that this strain of bed bug has the capacity to deploy certain enzymes that “may play a role in detoxifying the pyrethroid deltamethrin” — in other words, neutralizing the lethal effects of this insecticide.
• The results “indicate that highly-resistant bed bug populations can have multiple genetic mechanisms conferring resistance to pyrethroid (and possibly other) insecticides.”

The researchers conclude, “It is reasonable to suggest that the genes responsible for these resistance mechanisms … have been selected for in populations that have been subjected to long-term insecticide pressure.”

Tags: bedbugs, science, consumer affairs