The Chemical War Against Bed Bugs
By Rosemary Drisdelle, author of Parasites: Tales of Humanity's Most Unwelcome Guests
December 8th, 2009
Can the insecticide resistant creatures withstand even modern bed bug extermination technology
Bed bugs have been around a long time, in fact Cimex lectularius, the species that bites humans in temperate regions, probably fed on bats first and developed a taste for human blood when our distant ancestors lived in caves. Fast forward to the twentieth century and the advent of insecticides, and industrialized countries thought they had beaten the bed bug.
The bed bug’s retreat continued until at least the 1980s in the United States, perhaps later in some regions, but today the pests have resurged throughout the industrialized world. Reports of bed bug infestation have more than doubled since the turn of the century in cities like San Francisco, New York, Vancouver, Toronto, and London, England.
Sarah Delany, who moved into a bed bug infested Montreal apartment, says “I never knew they were real… I couldn’t imagine finding that in my bed.” But she did find them in her bed. The bed bug bite experience, she says, “felt like an incurable disease.” She took to getting dressed outside and kept her purse in a plastic bag. Researchers propose a variety of explanations for the return of bed bugs including increased immigration and international travel, phasing out of insecticides such as DDT, and changes in bed bug extermination methods.
It appears, however, that the main factor is insecticide resistance. Getting rid of bedbugs has never been easy. Because they lie hidden in cracks, behind curtains and baseboards, and anywhere dark where their flat bodies will fit, it’s notoriously difficult to wipe out a bedbug infestation with a single application of insecticide. Some bugs avoid the chemicals while others, like bed bugs survive exposure because they have a genetic mutation that makes them less vulnerable. After an attempt at bed bug extermination, survivors multiply unchecked. Those with a mutation that gives insecticide resistance pass it to offspring, replacing the original, mostly sensitive, infestation with one where many bugs are resistant. Repeated use of insecticides drives this: Dr. Wang from Rutgers University states that “as long as we use pesticides frequently, bed bug insecticide resistance will occur.”
Once bed bug resistance appears, further efforts towards getting rid of bed bugs are even less likely to succeed. Delany’s apartment remained infested a year later, after three different bed bug exterminators and five treatments. If various insecticides were used, surviving bed bugs may have had multiple insecticide resistance. Worse, bed bugs are known to avoid many insecticides, so treatment of one apartment causes them to move to another, spreading both infestation and resistance. Persistent bed bug infestation in apartment buildings is common. So are infested hotel rooms.
Barbara Trejo, a former Los Angeles resident, checked into a seaside hotel in Cyprus and the following morning “woke up with red spots and bites all over.” A housekeeper told her the entire hotel was infested, and much of the rest of Trejo’s vacation was spent taking refuge on the beach. Luckily, she “never had any with [her] when [she] left,” but she easily could have: bed bugs like suitcases too. The chemicals we have against bed bugs are rapidly becoming ineffective. Although data are scanty, recent studies show widespread insecticide resistance. Bed bug exterminators, therefore, are seeking innovative solutions to the problem. Wang thinks that “success [relies] on integrated pest management (IPM) rather than one miracle tool that is yet to be discovered.”
Integrated pest management can include mattress encasements, traps, treatment with high temperatures or hot steam, and application of diatomaceous earth dust or desiccants. A study by Wang and colleagues, published in 2009, indicated that mattress encasements combined with hot steam, diatomaceous earth, and bug traps can work at least as well as pesticide application. These measures have additional benefits: they don’t expose people to toxins or induce bedbugs to disperse.
The complacency of the mid-twentieth century resulted in an absence of accurate statistics and scientific research on bed bugs from that time, but the situation’s changing. The experts are calling for better monitoring, more research on insecticide resistance and IPM, and heightened public education. Meanwhile people can prevent infestations by keeping an eye out for bed bugs both at home and away, and using non-chemical IPM precautions to foil the pests.