Inbreeding is what's secretly driving all the bedbug infestations

Bedbugs were pretty much wiped out in the United States back in the 1950s, but over the past decade they've returned with a vengeance. They're tougher and more resistant to insecticides than ever before, and it's all due to inbreeding.

Although bedbugs don't transmit disease, their bites can cause allergic reactions, and they represent a major economic and social threat to the owners and tenants of apartments, hotels, and other urban dwellings. Rajeev Vaidyanathan, the associate director of Vector Biology and Zoonotic Disease at SRI International, explains just how big a negative impact this bedbug resurgence has had:

"New York City alone spends between $10 million and $40 million per year on bed bug control, and these numbers are repeated in other major cities across the US. Over 95 percent of pest control agencies reported bed bugs as a priority in 2010, thus superseding termites as the number one urban pest."

Coby Schal and Ed Vargo, both entomologists at North Carolina State, have recently conducted analysis of the genetic diversity of bedbug infestations in North Carolina and New Jersey. They discovered that there were shockingly low levels of genetic diversity in these populations, indicating that these infestations likely began with as little as a single breeding pair of bedbugs.

That means bedbugs can withstand a tremendous amount of inbreeding without apparently the resultant loss of health and fitness that is seen in other species. This gives bedbugs a tremendous advantage, as they can quickly spread out across the entire apartment without have to worry about finding unrelated reproductive partners. Schal explains:

"Inbreeding gives bed bugs an advantage in being able to colonize. A single female that has been mated is able to colonize and start a new infestation. Her progeny and brothers and sisters can then mate with each other, exponentially expanding the population. With many organisms, extensive inbreeding would cause serious mutations that would eventually bring about an end to the population."

For more on the recent bedbug resurgence, check out the American Society of Tropical Medicine and Hygiene.

Image courtesy of CDC, credit Piotr Naskrecki.