Although the importance of non-chemical approaches for bed bug management has been reiterated time and time again, we continue to rely, sometimes solely, on synthetic pesticide application to control infestations. Recent studies show that non-chemical control methods can work exceptionally well for the management of bed bugs, especially for low-level infestations (Wang et al. 2016). The mechanical removal of bed bugs, installation of mattress encasements, laundering of infested fabrics and placement of interceptors are all viable options for controlling bed bugs, yet, synthetic pesticides are still the number one tool for bed bug management. This isn’t surprising; the application of synthetic insecticides is traditional protocol. However, with the rise in insecticide resistance and evolving customer preferences, is it time to consider bucking tradition?
According to the “State of the Naturals Market” report that appeared earlier this year in PCT magazine, customers are interested now, more than ever, in “green” solutions for pest management — in terms of both natural chemistries and Integrated Pest Management (IPM). There are, undoubtedly, opportunities to consider “green” treatments for the control of bed bugs. For instance, bed bugs often harbor in, near and around sleeping areas, i.e., places where customers may be sensitive to synthetic pesticide use. Additionally, sensitive accounts that may be receptive to “green” solutions (schools, day cares, hospitals, etc.) are frequently the same accounts that are susceptible to bed bug introduction. The opportunities to offer alternative bed bug management solutions might be rife, but will they be as effective as the application of synthetic pesticides?
This article will review two types of “green” management approaches and their potential: non-chemical methods and “green” pesticides. “Green” is defined here as the use of minimum-risk pesticides and/or non-chemical approaches. Minimum risk pesticides are exempt from the Federal Insecticide, Fungicide and Rodenticide Act, meaning that they do not require federal registration by EPA, but may require state registration according to state laws.
NON-CHEMICAL MANAGEMENT. The importance of non-chemical methods in the reduction of populations of bed bugs is not disputed (Kells 2006, Wang et al. 2009). In fact, most firms probably offer green bed bug treatments without advertising them. According to Dr. Mark Goodman (Plunkett’s Pest Control), “Traps, glueboards, monitoring, physical exclusion, changes in human behaviors, sanitation and many other controls are an intrinsic part of our work, but we don’t think of it as ‘green.’ We think of it as simply good effective pest control.” Non-chemical approaches are green, though, and are perceived by the customer as “safer” than the application of synthetic insecticides (Potter et al. 2007). Implementing chemical-free methods in a management program will significantly reduce the number of bed bugs in a dwelling and according to Dr. Changlu Wang, the labor needed to execute non-chemical protocols is similar to the labor needed to execute other protocols. Why, then, are non-chemical protocols typically a supplement to synthetic pesticide application as opposed to the focus?
A potential setback to the adoption of standalone non-chemical bed bug treatments is the level of education and engrained social behaviors of the target customer. If a customer is interested in non-chemical bed bug treatment, they should play an active role in treatment execution. However, the customer may not understand the time and effort required. Thus, it is important that the pest management professional communicate to the customer the importance of following each step in a non-chemical management plan very closely. For example, Wang et al. (2009) and Singh et al (2017) have demonstrated success with non-chemical treatments in apartment buildings when residents attended educational seminars prior to treatment. Study authors communicated important messages to residents such as, “how to prevent the introduction of new bugs.” A joint effort and understanding between the PMP and customer could increase the odds for treatment success and customer satisfaction.
NON-CHEMICAL methods. In addition to an educated customer, successful non-chemical treatment programs require the proper execution of control methods. Below are some of the most common non-chemical approaches, their pros and cons, and recommendations for their implementation in a pesticide-free management program.
Disposal of Infested Items: The disposal of heavily infested furniture, which is a quick, chemical-free way to reduce the number of bed bugs present, is often requested by customers. However, customers should not decide which items to eliminate without input from the PMP because in most cases, the disposal of infested items is not necessary. If the customer insists on furniture disposal, the PMP should mark the items to indicate bed bug presence. Additionally, the PMP should remove as many bugs as possible and wrap the item to prevent bed bug escape. The PMP should arrange a timely pickup with local waste management as well. The clear benefit to this method is the rapid removal of bugs, but the drawback is the cost of lost furniture and items for the customer.
Interceptors and Encasements: PMPs should inform the customer of the importance of interceptors as well as mattress and box-spring encasements. The PMP should place these items themselves to ensure that they are used and installed correctly. Studies show that interceptors are more reliable than visual inspections and contribute significantly to IPM program efficacy. PMPs should plan to return and inspect interceptors for bed bug activity at regular intervals.
Encasements are also a useful tool in bed bug management since the elimination of bed bugs from the bed is time consuming and bugs will re-infest mattresses and box springs as they move through the structure in search of blood meals. A proper encasement will be escape and bite-proof, meaning that bugs cannot enter, exit or feed through the encasement. The encasement also should have a secure end stop (area where the zipper sits in the final resting position). There should be no gaps in or near the zipper that smaller bed bugs can move through. The cost of quality encasements can be high, but inadequate encasements will make treatment more difficult and provide a false sense of security for both the PMP and customer.
Vacuuming: Frequent vacuuming will reduce the number of bed bugs and their eggs. Vacuuming is most effective when efforts are targeted, bed bugs are undisturbed and harborage areas are scraped aggressively using hose-end attachments (the plastic crevice tool is preferable). It is important to note that vacuuming, on its own, will not eliminate an infestation and is more effective in conjunction with other non-chemical approaches (Kraft and Pinto 2016). Ideally, the vacuum used during treatment is solely for the purpose of bed bug removal with filters that prevent allergen dispersal through the dwelling. The PMP should vacuum visible bed bugs and their eggs, as well as the floor around the bed, any upholstered furniture, baseboards, and infested cracks and crevices. PMPs should inspect the vacuum after treatment to ensure that bugs or eggs are not trapped in ridges of the hose or other crevices.
Silica gel or another desiccant can be sucked into the vacuum to kill remaining bed bugs and hoses can be taped to prevent bed bug escape. Vacuum filters either should be washed or sealed and disposed of after treatment. This method is great for removing multiple bed bugs all at once. However, it is labor intensive and requires the purchase of a vacuum by the PMP or customer, solely for the purpose of bed bug treatment.
Steam and Heat: The application of steam at 170°F or higher will kill bed bugs and their eggs on contact. It is advisable to use a steamer with low moisture emission to prevent the growth of mold on fabric surfaces. The customer or PMP should hold the steamer head directly over the target surface to ensure temperatures reach a lethal level — this can be checked using an infrared thermometer. If the customer can afford a heat treatment, this is another viable (but more expensive) non-chemical option.
However, even the most thorough heat treatments may miss a few bed bugs. Without a synthetic pesticide to do residual work, finding and removing stragglers may be difficult. Interceptors can be used in this case to supplement visual inspections. Finally, laundering and drying infested fabrics at high temperatures (>120°F) will kill bed bugs and their eggs. Each of these methods kills bugs effectively, but offers no residual effect, and may be labor intensive.
Although this information may be common sense for the PMP, it is not always common sense to the customer. Explicit instructions, demonstration and follow-up visits will likely be necessary to ensure that non-chemical tactics are being executed frequently and effectively enough to reduce population numbers. The PMP and customer should work together to come up with an effective plan that will fit the budget and habits of the customer, which is no small task. Additionally, some non-chemical approaches may not only be costly, but will require frequent physical movement, preparation and maintenance of belongings (bagging items, moving furniture, vacuuming, laundering, etc.).
Some customers may not have the space or capacity for this sort of upkeep. In fact, when Wang et al. 2009 observed IPM treatment failure, it may have been due to large piles of unwashed clothing as well as excessive clutter. A combination of green non-chemical and chemical approaches could be more effective in these situations, but are there existing green chemistries to do the job?
GREEN CHEMISTRIES. Before choosing a minimum-risk pesticide for bed bug treatment, it is important to check that the product has been adequately tested to ensure effectiveness. This may involve staying current in the pest control literature, which may not be an easy task. According to Mark Vanderwerp (Rose Pest Solutions) the data on green chemistry can be scant. He states, “Most of the published work on bed bug control is done with synthetic pesticides or non-chemical treatments.” He reiterated that when he attends conferences to learn more about novel management strategies, very few presenters discuss green pesticide efficacy.
Although peer-reviewed studies on the efficacy of green pesticides against bed bugs are rare, there is some evidence to indicate that many green formulas are not on par with synthetics. Singh et al. 2014 found that of 11 non-synthetic insecticides, only two minimum-risk products provided >90 percent mortality of bed bug nymphs in direct spray and forced exposure residual assays. Authors showed that residual efficacy of the minimum-risk products was less than that of the tested synthetic insecticides. Goddard (2014) evaluated six green insecticides against bed bugs and found that some product label claims contradicted data obtained in laboratory bioassays. Potentially unsubstantiated product claims, lack of peer-reviewed data, and the reduced efficacy and residual activity of some green formulas compared to synthetics could make minimum risk product use for bed bug management a challenge.
Other hurdles to the incorporation of minimum-risk formulas in green bed bug management programs could be: high formula cost, negative sensory experiences (strong formula smell, etc.) and unrealistic efficacy expectations on the part of the customer. Green formulas can be more expensive than synthetic formulas, often without any additional product efficacy claims. Many green liquid formulations are comprised of essential oils that leave residues and undesirable, strong odors. Applications of oily products may cause property damage, slip risks and other liability issues that are unappealing to a pest management company. Finally, although customers polled for market research such as the “State of the Naturals Market” report state that they are receptive to green products, it may be worth digging deeper to see if they are willing to choose green products even when the efficacy is not equivalent to a synthetic formula.
Due to the limitations of many minimum-risk liquid formulas, an alluring alternative green chemical option is the application of diatomaceous earth (DE) or amorphous silica gel dusts to control bed bugs. Some studies indicate that amorphous silica gel may perform better in the field than diatomaceous earth (Potter et al. 2014), but either way, dusts offer residual activity that liquid minimum-risk formulations might not. Although silica gel is technically synthetic, it is considered non-toxic, non-flammable, non-reactive and stable. Customers looking for a completely non-synthetic approach could use DE, although the customer should be informed of the very low risk of silica gel to humans and animals and its superior efficacy in controlling bed bugs. In a field study, CimeXa-only treatments reduced 98.1 percent of bed bugs in apartment dwellings (Potter et al. 2014).
CAN WE GO GREEN? Do PMPs have the right tools to control bed bug infestations without synthetic chemicals? The peer-reviewed research indicates that they do (Bennett et al. 2015). In spite of this, the “State of the Naturals Market” report states that only 18 percent of PMPs rank bed bugs as one of the top three pests they are most likely to treat with green products. This is well below ants (49 percent), occasional invaders (34 percent), cockroaches (32 percent), mosquitoes (29 percent) and spiders (27 percent). Research delving into the reasons behind the lack of green chemistry offered by pest control companies would be informative, especially in light of the clear interest of customers in these alternatives according to the “State of the Naturals Market” report. It also would be informative to understand whether pest control companies are reporting the use of non-chemical control options when asked if they offer green bed bug treatments.
With the rise of insecticide-resistant bed bugs, a plethora of sensitive accounts, and heightened customer concern regarding the use of synthetic pesticides, it is the perfect time to develop and advertise effective green strategies for bed bug management to customers. A shift to the implementation of non-chemical methods as primary strategies for bed bug control will help reduce pesticide input in indoor environments and reduce the selection pressure for the evolution of pyrethroid resistance. Although there are hurdles to overcome, green bed bug protocols can allow PMPs to untie the tether to synthetic chemicals when necessary and with enough vigilance, green bed bug control is poised to be “meaner” than ever before.
Dr. Sydney Crawley is the public health entomologist at Scotts Miracle-Gro in Marysville, Ohio.