Bed bugs target of research, Extension initiatives
“Don’t let the bed bugs bite” may seem like a trite outdated bedtime wish, but unfortunately it is becoming more real for homeowners and institutions around the country. Bed bugs are back with a vengeance, and N.C. State University entomologists are looking for solutions to the problem and helping educate the public.
In November, N.C. Cooperative Extension partnered with other agencies to host workshops in Pitt and Forsyth counties for Extension county staff members, county environmental health specialists, social workers, housing code officials and others who deal with housing and pest issues.
In addition, entomology researchers at N.C. State are busy studying bed bug infestations, looking for genetic clues about the origins of this generation of bed bugs, as well as possible strategies for control. Dr. Coby Schal, Blanton J. Whitmire Distinguished Professor and urban entomologist, and others associated with bed bug research have been featured in numerous news stories about bed bugs, including appearances on “The People’s Pharmacy” syndicated radio talk show and WRAL-TV news.
Topics covered at the two Extension workshops included information on the history and biology of bed bugs, prevention and treatment strategies, inspecting for and detecting bed bugs, as well as rules and regulations on bedding. Partners offering the workshop with Extension were the N.C. Department of Environment and Natural Resources and its Public Health Pest Management Section, N.C. Department of Agriculture and Consumer Services, N.C. Mosquito and Vector Control Association, and the N.C. Pest Management Association.
Dr. Mike Waldvogel, Extension entomology specialist in the College of Agriculture and Life Sciences, said bed bugs are becoming a problem in homes and institutions because of increased international travel; decreased routine pesticide spraying as institutions adopt integrated pest management (IPM) strategies over routine and often unnecessary spraying; and increased resistance of bed bugs to several categories of pesticides.
Education is the key to helping county agencies and the public deal with bed bugs, Waldvogel said. One Extension agent said she routinely gets calls from people who know they have a bed bug problem but feel that they can’t afford professional pest control services.
Waldvogel and other workshop leaders stressed the importance of getting professional help with a bed bug infestation. Rick Santangelo, an N.C. State research specialist, highlighted steps to take to avoid bringing hitchhiking bed bugs into the home. The workshop also included demonstrations of using dogs to detect bed bugs, inspecting a mattress for bed bugs and using heat to treat for bed bug infestation.
Robert Brannon of Integrated Pest Inspections demonstrated how dogs can be trained to effectively sniff out bed bugs in homes. Within seconds, his trained beagle detected a vial of four bed bugs that Waldvogel had taped under an empty chair. After handling the vial and rubbing his glove on a podium nearby, Brannon got the dog to respond to the odor of bed bugs there as well.
Brannon said that trained dogs can detect the scent of bed bugs with 90 to 95 percent accuracy, while humans conducting a visual inspection will find bed bugs only 30 percent of the time. He cautioned, however, that while dogs can isolate areas where bed bugs are likely to be, property owners must ultimately decide what steps to take to resolve the problem.
Scott McNeely of McNeely Pest and Wildlife Solutions demonstrated how heat can be used to control bed bugs. The company set up a conference room in Pitt County and an office in Forsyth County that were heated to 135 degrees, the temperature that a home must reach for five hours in order to kill bed bugs. In addition to heaters placed throughout the home, monitors are used to make sure that even the internal temperature of furniture and mattresses reaches 135 degrees.
For the past four decades, bed bugs have posed few problems in the United States, other than an occasional outbreak in poultry houses, Schal said. DDT and other powerful pesticides that followed it largely controlled the populations. So all research initiatives on bed bugs ceased in the 1950s. Getting back into the arena of bed bug research essentially means starting from scratch.
To determine what pesticides bed bugs can survive, Schal’s lab maintains a collection of bed bug populations collected around the United States. The insects are kept alive with the help of a feeding apparatus that provides rabbit blood to colonies of the insects.
Through dosing with various pesticides, the researchers can determine which pesticides effectively kill the insects and which do not. And that information alone can provide clues as to where today’s bed bugs came from.
One thing that colonies from all over the United States have in common is a very high resistance to pyrethroid-type pesticides. The main places that bed bugs would contact pyrethroids in this country would be in kitchens or bathrooms – places regularly treated for cockroaches, but not where you would find bed bugs. So the United States’s pyrethroid-resistant bugs likely came from a region where those pesticides are used extensively around beds.
That could happen in Africa, Southeast Asia or South America, where bed bugs seeking a human blood meal might encounter pyrethroid-treated bed nets, designed to prevent biting by malaria-carrying mosquitoes. So Schal believes that it is likely the bed bugs found in U.S. hotels, homes and apartments may be descendants of bugs that came from those areas of the world, where they evolved resistance to pyrethroids.
In addition to dosing the bed bug colonies with pesticides to identify chemicals they may have resistance to, the researchers are using molecular tools to extract DNA from dead bed bugs and look for genetic clues for resistance. They have learned that the U.S. bed bug populations typically have two genetic mutations that confer resistance. If both these mutations occur, the insects’ resistance to pesticides increases greatly.
Bed bug researchers are using other genetic tools to “fingerprint” bed bugs to suggest how they colonize buildings and rooms. Using such technology, Schal’s group, in collaboration with population geneticist Dr. Ed Vargo, determined that a bed bug infestation in a 10-story building was so genetically similar that all the bugs likely came from a single source.
“An entire infestation could be founded by one pregnant female,” Schal said.
Researchers working on the bed bug problem include Schal and Vargo, as well as post docs Dr. Warren Booth and Dr. Alvaro Romero, who is working under a National Science Foundation fellowship. Virna Saenz is a doctoral student, and Rick Santangelo is a research specialist.
Romero’s work includes investigating the human scents that attract bed bugs to humans, along with the body heat and carbon dioxide that we exhale. Such information could lead to potential “scent-based” traps for bed bugs.
Saenz is working with College of Veterinary Medicine researchers Drs. Edward Breitschwerdt and Michael Levy to find out if bed bugs could potentially transmit Bartonella, an arthropod-borne bacteria that may be responsible for some chronic and debilitating neurological illnesses in humans.
— Natalie Hampton