Behavioral Responses of the Bed Bug to Permethrin-Impregnated ActiveGuard™ Fabric

The Efficacy of a Pyrethroid-impregnated Mattress Liner on Multiple International Strains of Cimex lectularius (Hemiptera: Cimicidae) and Cimex hemipterus (Hemiptera: Cimicidae)

Modern bed bugs are resistant to multiple insecticide classes, particularly the pyrethroids. The efficacy of pyrethroid-impregnated mattress liners marketed for bed bug management has been variable. This study evaluated the efficacy of a permethrin-impregnated mattress liner, ActiveGuard, against 24 bed bug strains, consisting of both Cimex hemipterus (F.) and Cimex lectularius L. A 'mat assay', employing an allethrin-impregnated mat, was used to establish the pyrethroid resistance profile of all strains. Three experiments were conducted to evaluate the effect of ActiveGuard exposure on bed bug knockdown: 1) exposing the bed bugs continuously on the liner for up to 24 d, 2) holding the bed bugs on the liner for either 4 or 6 h, and 3) placing a noninsecticide treated fabric above the liner with the bed bugs held continuously on top. Our results indicated that all modern strains (collected within the last 15 years during the current resurgence) were pyrethroid-resistant, although the magnitude of resistance was highly variable between strains. In the continuous exposure study, an incomplete knockdown was recorded for most modern bed bug strains, with some having no knockdown even up to 7 d of constant exposure. In the 4 or 6 h exposure study, the level of knockdown was reduced even further, and very few bed bugs were knocked down in the double fabric study. The results of this study indicate that pyrethroid-impregnated mattress liners are not likely to be effective in the management of most modern bed bug infestations involving either C. hemipterus or C. lectularius.

Historical and Contemporary Control Options Against Bed Bugs, Cimex spp

Bed bugs (Hemiptera: Cimicidae) are an important group of obligate hematophagous urban insect pests. The global resurgence of bed bugs, involving the common bed bug, Cimex lectularius L., and the tropical bed bug, Cimex hemipterus (F.), over the past two decades is believed to be primarily due to the development of insecticide resistance, along with global travel and poor pest management, which have contributed to their spread. This review examines and synthesizes the literature on bed bug origins and their global spread and the literature on historical and contemporary control options. This includes bed bug prevention, detection and monitoring, nonchemical and chemical control methodologies (and their limitations), and potential future control options. Future research needs are highlighted, especially the factors behind the modern resurgence, the necessity of identifying differences between the two bed bug species relevant to control, and the need to improve insecticide test protocols and management strategies.

Methods for Testing Repellents Against Bed Bugs (Hemiptera: Cimicidae)

Bed bug repellents should not only prevent humans from being bitten but impede an infestation of personal belongings. Only a few test proposals for evaluating the efficacy of repellents against bed bugs have been published so far. In the present study, two test systems were assessed for efficacy testing with five potential bed bug repellents (cinnamon oil, icaridin, N,N-diethyl-3-methylbenzamide (DEET), permethrin, and margosa extract). The first test setup was a harborage choice test system that consisted of a crystallizing dish with a treated and an untreated harborage. Sixty minutes and 24 h after treatment, DEET, icaridin, and cinnamon oil showed the highest repellency with a median proportion of at least 99% repelled bed bugs. The second test system was a barrier test. Bed bugs were attracted by CO2 and heat to cross filter papers treated with the potential repellents. The repellency of substances was significantly lower in comparison to the harborage choice test, except for DEET. The latter showed the highest repellency (97%) against bed bugs 24 h after application compared to controls. Results show that bed bugs are less sensitive to repellents when searching for a bloodmeal than when searching for a shelter.

Efficacy of a Fungal Biopesticide for Bed Bug Management Is Influenced by the Toxicity and Associated Behavioral Avoidance of Harborages on Insecticide-Impregnated Box Spring Covers

Bed bugs spend most of their lives hiding in harborages, usually in the seams of mattresses and box springs and in crevices of bed frames. For insecticidal products that target these shelters, the repellency of the products for bed bugs may influence their duration of contact. Bed bugs are known to avoid contacting surfaces treated with certain insecticides. The fungal biopesticide Aprehend contains spores of the entomopathogen, Beauveria bassiana. It is sprayed around bed frames, box springs, and furniture where bed bugs are likely to walk, which includes potential shelters. Here, I investigated the influence of a permethrin-impregnated cover, ActiveGuard, on bed bug sheltering behavior and the effectiveness of combining ActiveGuard with Aprehend. Bed bugs avoided harboring in a shelter constructed with ActiveGuard compared to a nontoxic encasement-type cover. This avoidance behavior reduced mortality induced by ActiveGuard shelters compared to forced continuous contact on the ActiveGuard cover. However, while bed bugs also avoided Aprehend-treated ActiveGuard shelters, the combined treatment induced almost complete mortality and more quickly than Aprehend-treated shelters made of the encasement-type cover. This suggests compatibility between the two integrated pest management (IPM) tools even though the bed bug's avoidance behavior would suggest otherwise. Since Aprehend is highly effective against pyrethroid-resistant bed bugs, its use would provide more effective control where bed bug populations are more resistant to the permethrin-impregnated cover.

Persistence and Lethality of a Fungal Biopesticide (Aprehend) Applied to Insecticide-impregnated and Encasement-type Box Spring Covers for Bed Bug Management

The newly developed fungal biopesticide Aprehend, containing spores of Beauveria bassiana, is the first biological control agent to be incorporated into management programs to control the common bed bug (Cimex lectularius L.) (Hemiptera: Cimicidae). Aprehend is sprayed as barriers where bed bugs are likely to walk and pick up spores as they search for a bloodmeal. A key application target for Aprehend is the box spring, which may be covered by encasement-type or insecticide-impregnated covers. Since some insecticides can reduce the persistence of fungal spores, we tested the efficacy and spore germination percentages of Aprehend when applied to the two types of box spring covers. We found that spore germination was about 11% lower on the permethrin-impregnated ActiveGuard cover than on the encasement-type AllerEase cover. However, bed bugs exposed for 15 min to Aprehend on the two box spring covers suffered similarly high levels of mortality irrespective of the cover material. Thus, there was no inhibitory or additive effect of the ActiveGuard cover on bed bug mortality. Lastly, overall mortality was higher if bed bugs were exposed to Aprehend-treated ActiveGuard than the ActiveGuard cover alone. Our findings indicate that if pest managers are using ActiveGuard covers in combination with Aprehend, best practice would be to use ActiveGuard on mattresses and apply Aprehend directly to the box spring or to a box spring covered by an encasement-type cover.

Effects of the Botanical Compound p-Anisaldehyde on Horn Fly (Diptera: Muscidae) Repellency, Mortality, and Reproduction

The horn fly, Haematobia irritans irritans (L.) (Diptera: Muscidae), is an economically important obligate blood feeder that mainly attacks cattle in Europe, Asia, and North and South America. As horn fly resistance to conventional insecticides becomes more common, alternative control tactics, such as application of bioactive botanical natural products are being investigated. p-Anisaldehyde has been found in many plant species, and it has shown effects that include mortality, attractancy, and interference with host seeking. The series of bioassays we developed was effective for assessing a range of horn fly responses to chemicals and probably those of some other filth fly species. In our study, p-anisaldehyde was lethal to horn fly eggs at concentrations of 0.00001%, and possibly less. Mixed into cow manure, 5000-20,000 ppm p-anisaldehyde reduced horn fly larvae by 85.4%-100%. p-Anisaldehyde caused some immobilization of adult horn flies when exposed by direct contract with spray droplets and by fumigation. Mortality was 90%-100% in response to 5%-10% concentrations by 30 min, and LD50 and LD90 values are reported for five times from 30 min-4 h. Complete horn fly mortality was achieved by fumigation with 0.75% p-anisaldehyde by 3 h in an enclosed space, and we determined that fumigation was more (≈12.5-fold) lethal to adult horn flies than sprayed droplets. Although horn flies were not repelled by p-anisaldehyde in static air tube olfactometers, the compound completely deterred feeding from cotton pads soaked in bovine blood in response to concentrations of 0.6% and greater in ventilated containers. Although horn fly control is not likely to use fumigation methods, p-anisaldehyde might be useful for adult control using sprays and egg and larval control using feed-through techniques. Exposure to sublethal concentrations of p-anisaldehyde did not affect horn fly egg production and hatching. Aside from causing different responses in the same species of arthropod, p-anisaldehyde has a variety of effects on other arthropods. Research on this compound as a potentially multifaceted pest management tool has been sparse. This study, for example, is the first to demonstrate p-anisaldehyde's feeding deterrent and immobilization properties and effects on different life stages.

Impact of sublethal exposure to a pyrethroid-neonicotinoid insecticide on mating, fecundity and development in the bed bug Cimex lectularius L. (Hemiptera: Cimicidae)

Sublethal exposure to an insecticide may alter insect feeding, mating, oviposition, fecundity, development, and many other life history parameters. Such effects may have population-level consequences that are not apparent in traditional dose-mortality evaluations. Earlier, we found that a routinely used combination insecticide that includes a pyrethroid and a neonicotinoid (Temprid^® SC) had deleterious effects on multiple bed bug (Cimex lectularius, L.) behaviors. Here, we demonstrate that sublethal exposure impacts physiology and reproduction as well. We report that sublethal exposure to Temprid SC has variable aberrant effects on bed bugs depending on the strain, including: a reduction in male mating success and delayed oviposition by females. However, after sublethal exposure, egg hatch rate consistently declined in every strain tested, anywhere from 34%-73%. Conversely, impact on fifth instar eclosion time was not significant. While the strains that we tested varied in their respective magnitude of sublethal effects, taken together, these effects could reduce bed bug population growth. These changes in bed bug behavior and fecundity could lead to improved efficacy of Temprid SC in the field, but recovery of impacted bugs must be considered in future studies. Sublethal effects should not be overlooked when evaluating insecticide efficacy, as it is likely that other products may also have indirect effects on population dynamics that could either aid or inhibit successful management of pest populations.

Behavioral effects of sublethal exposure to a combination of β-cyfluthrin and imidacloprid in the bed bug, Cimex lectularius L

BACKGROUND

Bed bugs (Cimex lectularius) are blood-feeding insect pests with public health relevance. Their rapid evolution of resistance to pyrethroids has prompted a shift to combination products that include both a pyrethroid and neonicotinoid insecticide. Insecticides have both a direct impact on mortality and an indirect effect on behavior. Thus, we assessed the sublethal effects of a widely used combination product containing β-cyfluthrin (a pyrethroid) and imidacloprid (a neonicotinoid), as unexpected behavioral changes after exposure have been known to affect efficacy of insecticides.

RESULTS

We found that bed bugs exposed to sublethal doses of a combination product containing β-cyfluthrin and imidacloprid did not feed as effectively as untreated bugs. Their locomotion behavior was also reduced. However, aggregation in response to the presence of conspecific harborages was not affected by sublethal exposure.

CONCLUSION

Bed bugs exhibit behavioral changes after sublethal exposure to a combination product that could affect pest management choices and outcomes. A reduction in host-finding efficiency and feeding could complement the lethal effects of the insecticide. Alternatively, reduced locomotion following exposure could limit ongoing contact with insecticide deposits. However, an overall reduction in movement indicates that treatments are unlikely to cause dispersal of bugs to adjacent dwellings. © 2016 Society of Chemical Industry.

The influence of time and distance traveled by bed bugs, Cimex lectularius, on permethrin uptake from treated mattress liners

BACKGROUND

Residual insecticides interrupt the dispersal of bed bugs (Cimex lectularius, L.), but one of the issues encountered with residual applications is understanding the uptake of active residues by the insect. This study determined permethrin uptake by bed bugs walking on the ActiveGuard^® Mattress Liner product, via a combination of video recording in arenas and gas chromatography analyses.

RESULTS

The best model for estimating permethrin uptake utilized a covariance model (r²  = 0.469) with two factors: time of exposure (F_{1,55 =} 2.44, P < 0.001) and distance traveled (F_1,55  = 0.30, P = 0.0460). Bed bug permethrin uptake was 15.1 (95% CI: 10.3-22.1) ng insect^-1 within 1 min exposure, 21.0 (15.0, 31.0) ng insect^-1 within 10 min and ≈ 42 (29.8, 60.6) ng insect^-1 within ≥50 min exposure. Correcting for percentage recovery, these values would be increased by a factor of 1.21.

CONCLUSION

This permethrin-treated fabric provides a surface from which bed bugs begin rapidly to absorb permethrin on contact and within the first 1 cm of travel. Variability in uptake was likely a result of grooming and thigmotaxis, and future work should use quantitative methods to study behaviors and formulations that increase exposure to the toxicant. © 2016 Society of Chemical Industry.

Sublethal Effects of ActiveGuard Exposure on Feeding Behavior and Fecundity of the Bed Bug (Hemiptera: Cimicidae)

Sublethal exposure to pesticides can alter insect behavior with potential for population-level consequences. We investigated sublethal effects of ActiveGuard, a permethrin-impregnated fabric, on feeding behavior and fecundity of bed bugs (Cimex lectularius L.) from five populations that ranged from susceptible to highly pyrethroid resistant. After exposure to ActiveGuard fabric or untreated fabric for 1 or 10 min, adult virgin female bed bugs were individually observed when offered a blood meal to determine feeding attempts and weight gain. Because bed bug feeding behavior is tightly coupled with its fecundity, all females were then mated, and the number of eggs laid and egg hatch rate were used as fecundity measures. We observed that pyrethroid-resistant and -susceptible bugs were not significantly different for all feeding and fecundity parameters. Bed bugs exposed to ActiveGuard for 10 min were significantly less likely to attempt to feed or successfully feed, and their average blood meal size was significantly smaller compared with individuals in all other groups. Independent of whether or not feeding occurred, females exposed to ActiveGuard for 10 min were significantly more likely to lay no eggs. Only a single female exposed to ActiveGuard for 10 min laid any eggs. Among the other fabric treatment-exposure time groups, there were no observable differences in egg numbers or hatch rates. Brief exposure of 10 min to ActiveGuard fabric appeared to decrease feeding and fecundity of pyrethroid-resistant and susceptible bed bugs, suggesting the potentially important role of sublethal exposure for the control of this ectoparasitic insect.