Abstract
Most field studies on Cimex lectularius are conducted in residential or hospitality industrial settings. Cimex lectularius infestations in office settings are reported, but are rarely studied. An office environment (~875 m 2 ) consisting of 105 cubicles or pod-seating areas with persistent C. lectularius sightings over a 2-yr period was evaluated for 90 d through intensive trapping to determine C. lectularius distribution and to eliminate the infestation. The study area was partially occupied during the study period. Two treatments of amorphous silica dust (112.5 g dust in total) were applied 29 and 57 d after the first day of monitoring. A total of 32 C. lectularius were captured by interceptors over a period of 55 d. Dry ice traps captured eight additional C. lectularius. Visual inspections identified one chair with live C. lectularius and eggs. The infestation was eliminated on 69 d after initial installation of interceptors. Spatial analysis using Ripley's K and L functions showed a high level of aggregation up to a 15 meter scale. Dispersal of C. lectularius in office settings was limited. Intensive trapping plus limited insecticide dust treatments effectively detected and eliminated C. lectularius. The re-emergence of Cimex lectularius L. in North America over the past two decades is well documented (Hwang et al. 2005 , Wang et al. 2016 ) and infestations are occurring in many residential (Wu et al. 2014 ) and commercial environments (Potter et al. 2015 , Penn et al. 2017) . Much of the available literature on dispersal and management of C. lectularius focuses on situations in laboratory (Pfiester et al. 2009) , residential environments (Hwang et al. 2005 ) such as apartments (Potter et al. 2008 , Cooper et al. 2016 , Sutherland et al. 2017 ) and hotels (Potter et al. 2015 , Penn et al. 2017) . While these studies help to understand infestation persistence and dispersal of C. lectularius, there is a lack of understanding as to whether these same observations hold true in nonresidential environments such as office settings. Cimex lectularius spend the majority of their time aggregated in hidden refugia during photophase (Reis and Miller 2011) where all stages of the insect occur along with their byproducts such as frass and exuvia (Reinhardt and Silva-Jothy 2007) . They are able to locate each other through a contact pheromone (Siljander et al. 2007 ) and an aggregation pheromone system (Collins 1968 , Siljander et al. 2008 , Gries et al. 2015 , Choe et al. 2016) . Hidden aggregation decreases the risk of predation (Siljander et al. 2008 ) and desiccation (Benoit et al. 2007 ) while increasing development rates (Saenz et al. 2014) . This cryptic life style creates difficulty in monitoring infestations and locating refugia. Additionally, C. lectularius will readily move between harborages using aggregate pheromones to identify nearby refugia (Weeks et al. 2013) . In spite of the relatively long periods of time that aggregation pheromone constituents persist (Choe et al. 2014 ), individuals will readily disperse and create new refugia over the course of an infestation (Reinhardt and Silva-Jothy 2007 , Pfiester et al. 2009 , Wang et al. 2010 , Cooper et al. 2015 ). Higher dispersal rates were found among adults in field settings (Wang et al. 2010 ) while high aggregation activity of nymphs was found in a laboratory study (Pfiester et al. 2009) . In low-income residential communities, dispersal is aided by human behavior (Wang et al. 2010) . Romero et al. (2017) demonstrated that multifamily dwellings have poor elimination success as most control strategies are reactive and lack a monitoring system to detect novel introductions or dispersing populations. Little is known about C. lectularius infestation, dispersal, detection, and management tactics in office spaces. Office environments are less often infested than home environments where bed bug hosts are available during scotophase hours of activity. Sheele et al. (2017a) found that the proportion of different life stages of C. lectularius obtained in a medical center, a nontraditional infestation, was different from those found in conventional infestations. Further, how C. lectularius establishes infestations in nontraditional settings differs than in conventional settings based on the way that people utilize and move through spaces. Typically, C. lectularius sightings in nontraditional settings such as medical centers display a higher proportion of adults to nymphs than in more traditional residential settings (Sheele et al. 2017b) . Once established though, nymphs are found in higher numbers. Still, the limited research in nontraditional environments leaves the knowledge of this pest incomplete. Cimex lectularius management predominantly relies on reactive treatment protocols using insecticide treatments with some heat treatments as well. Pest management contractors use chemical and nonchemical means to eliminate bed bugs in infested spaces. Insecticide applications are often combined with steam, mattress and box spring encasements, heat chambers, and traps (Doggett et al. 2012) . This is because pyrethroid insecticide resistance has been documented from most of the field populations (Romero et al. 2007 , Romero et al. 2009 , Zhu et al. 2010) and C. lectularius has shown resistance or potential resistance to other insecticidal classes as well (Lilly et al. 2015, Romero and Anderson 2016) . CimeXa (92.1% amorphous silica gel, Rockwell Labs Ltd., Kansas City, MO) is a product that demonstrated 100% efficacy as well as a horizontal transfer mortality effect (Singh et al. 2016) , although behavioral tolerance to insecticides was observed with pyrethroid-resistant strains of C. lectularius (Lilly et al. 2016) . Nonchemical treatments can be as effective as insecticide treatments in eliminating low-level C. lectularius infestations (Singh et al. 2017) . Cooper et al. (2015) found that using interceptors alone eliminated bed bugs in 50-100% of the apartments with a low number of bed bugs. Combined, these studies show that insecticide dust treatments along with intensive monitoring could be a viable option for the cost-effective bed bug elimination of low levels of infestations with minimal impact to human health. Detecting infestations and determining the bed bug spatial distribution in an environment is important for planning treatment strategies and successful elimination. Infestations in nontraditional environments such as office spaces are typically small. Harborage sites are more unpredictable. Therefore locating harborage refugia is difficult and there are few studies on proactive monitoring for C. lectularius in commercial settings by commercial pest control contractors. Scent detection canine teams have been shown to have the capability of locating C. lectularius (Pfiester et al. 2008) ; however, the effectiveness of their use in field settings has been shown to be inconsistent (Cooper et al. 2014) due to inconsistencies in canine team training. Interceptors have been found to be the more reliable monitoring tool (Wang et al. 2009a , Wang et al. 2016 ), compared to other forms of monitoring including visual inspections or tenant complaints. Adding lures to interceptors has been shown to increase effectiveness of interceptors (Singh et al. 2015a , Wang et al. 2017 ) and using specific colors such as black can increase the attraction of the interceptor by C. lectularius (Singh et al. 2015a) . A commercial bed bug monitor, NightWatch (BioSensory, Inc. Putnam, CT) that utilizes carbon dioxide (CO 2 ), heat, and chemical lure to attract bed bug was found to be useful for monitoring bed bugs (Wang et al. 2011) . However, it is very expensive and much less effective compared to dry ice traps and sugar yeast-based traps, which are very effective for detecting low-level infestations (Wang et al. 2011 , Singh et al. 2015a . Dry ice traps and sugar yeast traps are valuable tools for monitoring bed bugs in unoccupied environments, including nontraditional environments. Additionally, a better understanding of the spatial distribution of C. lectularius infestations in such environments can assist the pest management industry to develop monitoring protocols that will effectively identify refugia. This case study was designed to evaluate C. lectularius infestations, monitoring protocols and a minimum-risk bed bug treatment protocol in an office environment. The Rutgers Urban Entomology Laboratory was approached to assist a government agency's facilities management regarding a persistent C. lectularius infestation on an office floor that had persisted for several years. Our team used this unique opportunity to test a monitoring and treatment protocol. The objectives of this study were: 1) evaluate the effectiveness of an intensive trapping program in identifying infestations in an office environment, 2) investigate the spatial distribution pattern of a persistent recurring infestation, and 3) implement a minimal insecticide use protocol to eliminate C. lectularius.
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