An Ounce of Prevention

We all know that the best pest management is preemptive. Whether it’s sealing cracks and crevices or repelling termites with a barrier treatment, in pest management an ounce of prevention is truly worth a pound of cure. Keep the critters outside and you’ve won the game.

In the case of bed bugs, vigilant prevention is vitally important to prevent new infestations. However, when it comes to repellents — chemical compounds that prevent bed bugs from moving into a protected area — very few options exist. That could change, however, in the years to come, according to recent research that suggests repellents could be a viable weapon in the pest management professional’s bed bug arsenal.

“Once introduced, eliminating bed bugs is both expensive and difficult,” said Changlu Wang, Ph.D., an entomologist at Rutgers University. “Given these challenges, the public has an urgent need for materials and methods to reduce bed bug introductions and bites. A repellent product could help achieve these goals by discouraging bed bugs from moving to a protected area.”

REASONS FOR OPTIMISM. Wang and his colleagues at Rutgers studied the effectiveness of various substances used to repel bed bugs, and two groups of compounds demonstrated some success. The study, Repellency of Selected Chemicals Against the Bed Bug, was published in the December 2013 edition of the Journal of Economic Entomology.

Wang found that DEET at 25 percent or higher concentrations prevents more than 94 percent of bed bugs from crossing a treated area for at least eight hours in “high-pressure” situations, i.e., hungry bed bugs placed near strong food sources. Further, DEET-treated fabric remained “highly repellent” to bed bugs for 14 days, according to the study.

Wang also found that a relatively new group of natural compounds developed by a Danbury, Conn.-based firm, Bedoukian Research, also exhibited strong repellency against bed bugs.

“These non-irritant and odorless compounds are promising candidates as alternatives to DEET for reducing the spread of bed bugs and bed bug bites,” Wang wrote in the study.

While primarily known in the fragrance and flavoring industries, in the last couple years Bedoukian Research has been testing various chemical classes for use as insect repellents, says Karen McKenzie, entomology manager.

Specifically, the Bedoukian compounds that showed effectiveness in repelling bed bugs are called isolongifolanone, 3-methyl-5-hexyl-2-cyclohexenone, propyl dihydrojasmonate and Y-methyl tridecalactone.

“They are related to naturally occurring substances found in plants,” McKenzie says. “All but isolongifolanone have received Biochemical Classification by the U.S. Environmental Protection Agency. We did not apply for isolongifolanone, but it too should qualify. All these materials have shown to be repellent for a number of insects, including bed bugs, mosquitoes, agricultural pests, etc.”

Bedoukian representatives report they do not completely know how and why these materials have proven to be so effective at repelling bed bugs, but based on their consistent efficacy, the company plans to register and market a commercially available bed bug repellent.

“We are working with the Connecticut Agricultural Experiment Station to refine our bed bug repellent mixture. We also do testing in the presence of humans at a contract lab. Our testing is ongoing as we are still optimizing the formulation,” McKenzie says. “The timeline for a finished product is likely two to three years. Once we have established the optimum formula it needs to be registered with EPA. Then we can legally market a product.”

PRACTICAL APPLICATION. There are two obvious areas where repellents could be useful in the fight against bed bugs: one, keeping bed bugs off people; and, two, keeping bed bugs off surfaces.

“One of the areas where repellents may play a very important role is in the protection of people who are going into bed bug-infested environments, for example, inspectors who go into multi-family housing complexes, maintenance workers, home health aides, etc.,” says Rick Cooper, Ph.D., Cooper Pest Solutions, Lawrenceville, N.J. “Many of these people have a tremendous fear that if they go into a bed bug-infested area, they are going to take bugs home with them. I think that risk is relatively low, but repellents would provide an additional layer of protection and give the person a greater peace of mind,” Cooper adds.

DEET, for example, was found to be effective in Wang’s study for this type of use. However, Cooper cautions, not all DEET products are labeled for use on clothing. In fact, many DEET products are labeled for use only on skin. “So you must make sure that the product has a label that allows it to be used as a repellent on clothing,” Cooper stresses.

Dini Miller, Ph.D., entomology, Virginia Tech University, Blacksburg, Va., says she’s not convinced that repellents are a viable solution for preventing bed bugs from biting skin.

“I tried it myself with DEET and bed bugs on my skin,” she said. “The bed bugs ran away from the area where I sprayed the DEET, but they just went away from that area and tried to bite me someplace else. So, if we are using something to put on ourselves to keep the bugs from biting, do we have to cover every single inch, including between our toes? And by the end of the night it’s been worn off.”

The same goes for spraying mattresses, for example, to keep bed bugs from biting human hosts, Miller cautions. “Let’s say we had a repellent that could keep bed bugs off mattresses. That would be wonderful, however, as soon as the human being lays down on the mattress, they are the bed bug’s food, so they become a very strong attractant, and bed bugs are obligate blood feeders — they must feed on blood to survive — so suddenly that repellent’s activity could be severely hindered by the bed bug’s hunger. There’s a big difference between avoiding a surface initially because you don’t particularly like it, versus being willing to walk through fire because it is the only way to get to something that will save your life.”

While some like Miller are pessimistic about the prospects of repellents to prevent bed bug bites, many are more optimistic about the use of repellents to prevent bed bugs from moving onto certain surfaces.

In Wang’s study, separate 2.5 cm wide bands of DEET and the Bedoukian repellents both were effective in preventing bed bug movement. “This method could be used to reduce the spread of bed bugs from an infested room to surrounding units in multi-unit dwellings while waiting for treatment,” according to Wang.

Miller says she did some testing with Bedoukian’s compounds and in the lab they were able to keep bed bugs off surfaces. “While I don’t think there is much potential for repellents keeping bed bugs off your body, I do think there is potential in keeping them off surfaces,” she says.

By using repellents to make bed bugs less likely to move to certain areas and surfaces, such as closets and their contents, the potential exists to drastically reduce the areas within a structure needing pesticides or other treatments, while also reducing the amount of prep work, such as bagging personal belongings, etc., demanded of the homeowner.

“To prepare for bed bug treatments we are asking the resident to do a tremendous amount of prep work that may take weeks. Well, imagine if the resident only had to do half of that work because you have applied a repellent in certain areas and you could be assured that bed bugs weren’t in those areas. I think that alone would be a huge advantage,” Miller says.

The idea shows promise, Cooper says, but much more investigation is needed before repellents become an everyday part of the fight against bed bugs.

“Really no one has studied how repellents would be used to manipulate bed bug behavior as part of a prevention or control program and, at present time, we don’t really have repellents that are labeled for application within structures as part of a control program. So there is much more research needed,” Cooper says.

WHAT’S NEXT? The first step is finding an effective repellent. Based on Wang’s publication, we know that certain substances seem to have success in stopping or manipulating bed bug movement.

“Now, the next step is taking these repellents into the field to see how well they work and find out how they fit into a control program,” Cooper says. “We are still a couple steps away in determining how these products fit. I certainly think it’s worth looking into. Anything we can do to manipulate bed bug behavior and reduce pesticide use is something I think we should be exploring.”