Tips & Tricks

PMPs fighting the ongoing battle to control bed bugs should consider using the knowledge gained from field and lab research conducted by university entomologists. Susan Jones, Ph.D., professor of entomology and bed bug expert at Ohio State University, is one of those researchers. Her work over the years has provided important insights about the biology, behavior and control of bed bugs — and she shared some of her knowledge with participants of a recent bed bug webinar presented by PCT.

HEALTH/PSYCHOLOGICAL IMPACTS. “Bed bugs are recognized as the cause of various health problems in humans,” she said. “Skin reactions are experienced by seven of 10 people who have been bitten. Scratching the bite area can cause secondary bacterial infections. Cases of anemia have occurred when the bed bugs have sucked so much blood out of people that they’ve become iron deficient. Both asthma and anaphylactic shock have occurred in individuals who react severely to bites.”

Jones said bed bugs cause some psychological problems as well. “People who are very concerned about possible bites during the night lose sleep, which makes it difficult for them to function well the next day.”

According to Jones, the impact and role of bed bugs in diseases has been largely ignored. She pointed to previous studies that revealed bed bugs could carry 40+ human pathogens on their bodies, including bacteria and viruses. “A 2015 study showed that the digestive tract of a bed bug infected by a bacterium that causes trench fever can host that organism for up to two and a half weeks,” she said.

DEFECATION BEHAVIOR. Knowing that bed bugs and other blood-feeding bugs can potentially transmit those pathogens through their feces prompted an M.S. student in Jones’ lab to study bed bug defecation behavior following a blood meal. “We supplied rabbit blood in an artificial feeding system for the bed bugs and also used naked rats as another source of their blood meal. We wanted to learn how long bed bugs feed and where and when they defecate. We found that bed bugs defecated very close to their feeding site; and we learned they defecated very soon after feeding, ranging from approximately five seconds to two minutes after they withdrew their mouthparts.”

Jones said when and whether they defecated depended on how full they were after feeding. “Typically bed bugs will feed to repletion before they even detach from a host, and they feed every six to seven days on average.”

She also calculated a defecation index and found that females had a higher index than males. “So it seems that females are the most epidemiologically important stage,” she said.

MECHANICAL VECTORS? Jones said research in her lab is just one example of research that needs to be done to determine if bed bug behaviors allow them to vector disease organisms. “We need to do further research with various disease organisms to see if bed bugs could be mechanical vectors, also known as secondary vectors. It doesn’t seem that a bed bug bite itself results in disease transmission, but it could be that their feces facilitate pathogen transmission. If there’s a bed bug bite wound that itches, scratching it could expose that open wound to the bed bug feces, which potentially could contain a disease organism.”

Can humans acquire a serious disease through mechanical (secondary) transmission? “This is a question that really needs more research. Our preliminary research is providing some baseline information on defecation behavior after bed bugs have taken a blood meal,” she said.

Concerning the techniques used for bed bug control, Jones advocated very thorough inspections and finding and targeting their hiding places with residual insecticide.

BED BUGS WILL TRAVEL. PMPs need to know that bed bugs will travel, walking from room to room, she pointed out. “They may follow pipes or electrical wires or cables. In a 2012 study at a vacant house, we found them moving all over — not just in the master bedroom where visual inspections indicated that the bugs were most prevalent. We captured a total of 58 bed bugs of every stage — from first stage nymph to adult — in active monitors placed in the living room, dining room, and master and guest bedroom, she said.

“And bed bugs can be hitchhikers as well. One of my research assistants found 13 of them on his shoes after leaving an infested apartment. It was the one and only time he wore these shoes with a deep tread on the job. We always check our shoes when leaving an infested property,” Jones added. “I always promptly change my clothes and bag and launder them, using washer and dryer. It’s very important to sanitize them. If you can’t put shoes in a washing machine, put them in a dryer and let them tumble for 30 minutes at a high temperature.”

IDENTIFY ADULT MALES/FEMALES. “You also need to identify adult female and adult male bed bugs by looking at the tip of the abdomen. A female has a broad shape, while a male has a more tapered shape. However, you can’t differentiate the sexes in the nymph stage. And you can also determine if bed bugs are immature by looking at the development of their wing buds. Only adults have fully developed wing buds.”

Jones emphasized the fact that bed bugs require a proactive, diverse IPM strategy. “People want a magic bullet, but there’s no such thing,” she said. “On average it takes three insecticide treatments to eliminate a bed bug infestation. It’s a disservice when a company promises to do it in one job. You’ve got to go back and evaluate the success of your treatments. It takes anywhere from a week to two weeks for bed bug eggs to hatch and not every insecticide is going to be able to penetrate the egg shell. You really must use several different insecticides, including a residual; and you want to rotate, knowing that bed bugs can develop resistance very easily. Resistance is an inherited trait of a bed bug population.”

RESISTANCE RESEARCH. In Jones’ lab, her team looks at bed bug populations that they collect from the field to determine if they’re highly resistant or just moderately resistant. “We placed them on the very highest concentrations of insecticides — concentrations so high that the chemicals have actually precipitated out and the bed bugs were walking over the deposit. We saw that those bed bugs were able to withstand these incredibly high concentrations of insecticides.”

According to Jones, PMPs, not necessarily knowing the resistance status of their targeted bed bugs, should not rely solely on pyrethroid products. Bed bug bombs, also known as total-release foggers, are pyrethroid-based products that have very low concentrations of the active ingredient(s), she said. She cautioned against using total-release foggers, in part because bed bugs have developed resistance to pyrethroids in them.

“We’ve tested bed bug bomb products with label claims such as ‘kills on contact’ and ‘effective long-term control,’ but found that even when we had field-collected bed bugs out in the open and directly exposed (them) to the insecticide mist, they’ve walked away unscathed.”

Jones suggested that PMPs ask potential customers if they have used bed bug bombs. “If so, there’s a good chance the bed bugs scattered and the problem could be much worse than if they’d simply left things alone. That knowledge should be taken into consideration when pricing a job because it means there’s much more work to do,” she advised.

COMBINATION PRODUCTS. “There are now newer insecticides on the market that don’t strictly rely on pyrethroids,” she said. “These are combination products that include a neonicotinoid component, among others. My lab has tested combo products extensively, looking first at what happens when you directly spray bed bugs with any of them. We studied combo products on susceptible bed bugs, and on resistant bed bugs, and found that the bugs were rapidly killed regardless of what they were sprayed with.” Directly spraying the bugs causes contact kill.

Jones learned that contact kill isn’t the critical component. “It’s residual kill that’s needed,” she said. She also looked at the effectiveness of aged residues, and applied the combo products to fabric as well as plywood, and aged both. Her lab then exposed bed bugs to both the cloth and the plywood, placing them onto those surfaces for just 24 hours to learn the results. “All of the surfaces had at least one-month-old residual activity but we could very much see a difference in the impact on those bed bugs that were susceptible to pyrethroids versus those that were resistant. The maximum kill at one day for the pyrethroid resistant bugs was less than 50 percent. Even after seven days it was still less than 50 percent. With the susceptibles it was very close to 100 percent.

“Then we saw differences between the fabric and the plywood: fewer bed bugs died on plywood, which indicates that substrates influence insecticide availability,” she said.

INSECTICIDE STUDY. Jones also reported on a different study where she observed Temprid, a beta-cyfluthrin and imidacloprid product, and introduced bed bugs to the aged residues of that product on various substrates. She found that brief exposure caused rapid death of susceptibles but not the resistant bed bugs. The latter had to spend days in contact with the dry residue, she said.

“And the longer they stayed in contact with the dry Temprid residue, the higher the mortality,” she said. “This indicates that you had better spray the insecticide in bed bug hiding places where they’re going to stay, because it may take days before they absorb enough chemical to cause high levels of mortality.”

ACTIVEGUARD STUDY. Another product Jones’ team researched was the ActiveGuard mattress liner. “This is a fabric that has been impregnated with permethrin and has two-year sustained availability,” she said. “It’s not an encasement but is designed to be fitted on a box spring or a mattress and is supposed to be used for prevention, not for treatment of an established bed bug infestation. You knock down the bed bugs with other products and then use the ActiveGuard liners for ongoing protection.

“Our studies showed that ActiveGuard liners were not repellent to bed bugs. You want the bed bugs to stay on the liner to pick up a toxic dose of the chemical.”

Jones explained that her research lab at Ohio State University always uses multiple approaches to assess what’s going on before, during and after their research protocols.

“The bed bug research that we and our fellow university researchers do around the country can be key in determining the most effective IPM techniques for any given situation.”

The author has been writing about the pest management industry for more than 30 years. Email him at jfox@gie.net.