understanding bed bugInfestation And dispersal Patterns by xiuliliaofz


									/// special coverage: bed bugs

        understanding bed
        bug Infestation And
         dispersal Patterns
                           Multi-unit apartment buildings are more susceptible to
                            the rapid spread of bed bugs and chronic infestations
                            than single homes. So what can you do to stop them?

                                                                            Changlu Wang, Kurt
                                                                            Saltzmann, Eva Chin,
                                                                            Gary W. Bennett and
                                                                                Timothy Gibb

     Bed bugs and cockroaches caught in an interceptor placed between the
     apartment entry door and the refrigerator.

94   /// march 2010 www.pctonline.com
                                                                                                     special coverage: bed bugs ///

    t is safe to say that no other urban pests        determined through interviews, intercept-             after installation for a maximum of 15 weeks
    have elicited the degree of media hype            ing devices and visual inspections over a             (see Figure 1 below). The number of trapped
    and sensation as have bed bugs in recent          four-month intensive investigation.                   bed bugs was identified by location in the
years. Bed bugs have gone from a pest that                                                                  Interceptor (inner well or outer well) and
was almost non-existent to one that is now            MeTHOds. Here’s where we were and                     developmental stage (nymph or adult) was
of serious concern in all 50 states within a          what we did:                                          determined with the aid of a 10X hand-held
short period of time. To most people who                                                                    magnifier.
experience them for the first time, bed bug           Study Site. The study site was a 15-story                After an apartment was confirmed as be-
infestations are simply intolerable. The              apartment building located in Indianapolis,           ing infested with bed bugs, the two adjoining
economic losses and complaints associated             Ind. The building has 223, one-bedroom                units and the two units immediately across
with bed bugs continue to mount rapidly.              apartments occupied by low-income elderly             the hallway from the infested unit were also
As a result, the U.S. Department of Hous-             or disabled people. For several years, a local        inspected. If no bed bugs were found, the
ing and Urban Development listed “support             pest control contractor has used a variety of         apartments were re-inspected one to three
research to improve methods for preventing            chemical pesticides including pyrethroids,            months later to confirm the absence of bed
and combating bed bug infestations” as one            chlorfenapyr, alcohol and diatomaceous                bugs.
of the long-term strategies of the Healthy            earth in an effort to control bed bugs.
Homes Strategic Plan (www.hud.gov/                                                                          diSperSal aMong apartMentS.
healthyhomes).                                        Survey of bed bug infeStationS.                       We hypothesized that bed bugs frequently
   Despite the intense interest in curbing            We obtained a list of apartments with re-             move to the entry door area of an apart-
the global bed bug resurgence, there is com-          ported/suspected bed bug infestations from            ment and from there disperse into adjacent
paratively little scientific knowledge about          the management office in December 2008.               apartments via the hallways. To test this
this tiny insidious pest, especially regard-          A visual inspection and resident interview            hypothesis, we placed a pair of Intercep-
ing its behavior and ecology. As all scien-           (if residents were available) about the his-          tor traps in the hallways on either side of
tists who work in pest management realize             tory of the infestation, past bed bug control         the entrance doors of five bed bug-infested
such knowledge is critical in preventing and          efforts and resident awareness of bed bugs            apartments (see Figure 2 below). Because
controlling bed bug infestations. Now, more           in their apartments was conducted. In-                of aesthetic concerns from the manage-

Figure 1 (left). An interceptor placed under a bed leg. The inner and outer wells determine if the bed bugs are leaving from or coming to the furniture.
Figure 2 (right). Interceptors placed in the hallway to detect dispersing bed bugs.

than ever, it is crucial to study basic bed bug       spections required approximately 20 to 30             ment office, we removed the interceptors
biology and behavior if we are to stem the            minutes per team (or 0.7-1.5 person hours)            from the hallways seven days after installa-
epidemic resurgence of this difficult pest.           during which all bed bugs found (except the           tion. Interceptors were then placed inside
   Multi-unit apartment buildings are more            egg stage) were physically removed with               the entry doors in eight infested apart-
susceptible to rapid spread of bed bugs and           forceps.                                              ments (see Figure 3 on page 96). We ex-
chronic infestations than single homes.                                                                     amined the interceptors every two to three
During 2006-09, we monitored an outbreak              Monitoring populationS. Imme-                         weeks for 15 weeks.
and development of a bed bug infestation in           diately after visual inspection in each of 64
a high-rise apartment building in Indianap-           infested apartments, CLIMBUP Insect In-               ResuLTs ANd dIsCussIONs. What
olis, Ind. What follows are our findings on           terceptors were installed. These were evalu-          follows is a review of what we found
bed bug infestation and dispersal patterns as         ated and cleaned every two to three weeks             throughout the apartment building:

                                                                                                                          www.pctonline.com march 2010 ///   95
/// special coverage: bed bugs

     bed bug infeStationS. Based on visu-                 ments to compare the effectiveness of vi-        the sampled apartments.
     al inspections, bed bug counts from inter-           sual inspections and interceptors. After            Interviews and further field observations
     ceptor traps, resident and staff interviews          hand removal of all the bed bugs found by        revealed the following additional bed bug
     and records from the management office,              visual inspections, the interceptors further     dispersal mechanisms: bringing in infested
     101 known apartments were determined to              detected bed bugs in 17 apartments. Mean         furniture, using an infested wheelchair in
     be bed bug infested as of April 2009 (with-          visual count and interceptor count (12-          the building common areas, improper re-
     in 41 months of the first confirmed infesta-         week period) were 45 and 67, respectively.       moval of infested furniture (e.g., not wrap-
     tion). This number represented 45 percent            These results indicate that interceptors are     ping infested furniture in plastic prior to
     of the apartments in the building. Visual            an effective tool for monitoring bed bugs        removal from the building), resident visits
     inspections revealed 53 active infestations,         and evaluating the effectiveness of bed bug      to infested apartments or common areas,
     each with an average of 65 bed bugs. The             management programs. These results are           and visits by guests unknowingly harbor-
     very rapid increase and the persistence of           consistent with previous findings in that        ing bed bugs on their person, clothing or
     infestations in the apartments verified that         visual inspections, even by highly skilled in-   belongings.
     the existing pest control program was not            spectors, missed large number of bed bugs.
     adequate. It also became clear that more ef-                                                          MANAgeMeNT IMPLICATIONs. So
     fective management strategies must be in             bed bug population Structure.                    what should PMPs do when encountering
     place to prevent similar outbreaks in other          We examined a total of 1,540 trapped bed         bed bug infestations in apartment build-
     multi-unit dwellings.                                bugs and recorded their developmental            ings? Here are some tips your firm should
        Residents in 40 apartments with previ-            stage and location within the interceptors.      share with the building’s management.
     ously reported bed bug infestations were             Among them, 78 percent were nymphs               1. Understanding the basic ecology and be-
     interviewed to determine their level of              and 89 percent were found in the outer           havior of bed bugs can help direct manage-
     awareness of bed bugs in their apartments.           well of the trap. Location on the intercep-      ment practices and will significantly impact
     Among them, only 12 (30 percent) were                tor device is significant because finding        success.
     aware of current bed bug activity in their           more bed bugs in the outer well than in the      2. Property managers and pest management
     apartments. Visual inspection alone in these         inner well indicates that most of the bed        professionals must adopt building-wide bed
     40 apartments revealed 24 active infesta-            bugs missed by visual inspections were not       bug monitoring and treatment programs. Si-
                                                          on the furniture but were elsewhere in the       multaneous treatment will reduce bed bug
                                                          apartment (and were moving toward the            dispersal and help achieve building-wide
                                                          furniture at the time they were caught).         bed bug elimination.
                                                                                                           3. More aggressive education of the clients
                                                          diSperSal between apartMentS.                    and proactive monitoring are necessary to
                                                          Three out of the five pairs of interceptors      prevent new infestations, detect bed bug
                                                          placed in the hallways trapped two bed bugs      infestations in their early stage, and reduce
                                                          per pair after one week, supporting our hy-      the spread of bed bugs within and between
                                                          pothesis that bed bugs used hallways as a        communities.
                                                          route for dispersal. The mean visual count       4. Without changing current control prac-
                                                          from these five apartments before placing        tices, bed bug infestations may continue to
                                                          the interceptors was 196 per apartment. The      spread in our society and likely will become
                                                          average number of bed bugs detected be-          much more widespread in low-income
                                                          hind entry doors over the four-week period       housing in the years to come.
                                                          was six and the maximum was 42. Among
                                                          the 138 bed bugs examined that were caught       Note: Complete study results were published in
      Figure 3. An interceptor placed between the         at entry doors (dispersing), 30 percent were     the Journal of Economic Entomology 103: 172-177.
      apartment entry door and the refrigerator. An       nymphs, including first instars. The differ-
      experimental lure was placed in the inner well of   ence between the proportion of nymphs at         Acknowledgements: The authors thank M. Aboul
      the interceptor but was found to not contribute     entry doors vs. under furniture indicates        El-Nour for technical assistance, Indianapolis
      to the number of trapped bed bugs.                  that adult bed bugs were nine times more         Housing Agency staff for providing access to the
                                                          likely to disperse than nymphs.                  apartments, S. McKnight for providing study ma-
     tions. Thus, at least 50 percent of the in-             The total number of bed bugs from in-         terials and John Obermeyer for providing photos.
     terviewed residents did not know of an               terceptors placed at entry doors were posi-
     existing infestation even though they were           tively correlated with the visual counts.        Changlu Wang is with the Department of Ento-
     living with it. The discrepancy between              Most of the neighboring apartments were          mology, Rutgers University, New Brunswick, N.J.
     the numbers of reported (12) and actual              either not infested or had much lower bed        Kurt Saltzmann, Eva Chin, Gary W. Bennett and
     (24) infestations suggests the necessity for         bug populations than the sampled apart-          Timothy Gibb are with the Center for Urban and
     inspection of all apartments in a building           ments. We therefore considered the bed           Industrial Pest Management, Department of En-
     once any bed bug infestations are found.             bugs trapped in the interceptors at entry        tomology, Purdue University, West Lafayette, Ind.
        We chose 20 bed bug-infested apart-               doors as dispersing from, not moving into,       Wang can be reached at cwang@giemedia.com.

96   /// march 2010 www.pctonline.com

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