Host-Seeking Behavior in the Bed Bug, Cimex lectularius

Abstract

The reemergence of the bed bug, Cimex lectularius Linnaeus, has recently spawned a frenzy of public, media, and academic attention. In response to the growing rate of infestation, considerable work has been focused on identifying the various host cues utilized by the bed bug in search of a meal. Most of these behavioral studies examine movement within a confined environment, such as a Petri dish. This has prevented a more complete understanding of the insect's host-seeking process. This work describes a novel method for studying host-seeking behavior, using various movement parameters, in a time-lapse photography system. With the use of human breath as an attractant, we qualitatively and quantitatively assessed how bed bugs navigate their environment between its harborage and the host. Levels of behavioral activity varied dramatically between bed bugs in the presence and absence of host odor. Bed bugs demonstrated not simply activation, but attraction to the chemical components of breath. Localized, stop-start host-seeking behavior or alternating periods of movement and pause were observed among bed bugs placed in the environment void of human breath, while those exposed to human breath demonstrated long range, stop-start host-seeking behavior. A more comprehensive understanding of bed bug host-seeking can lead to the development of traps and monitors that account for unique subtleties in their behavior. The time-lapse photography system uses a large, artificial environment and could also be employed to study other aspects of the insect's behavioral patterns.

Keywords: Cimex lectularius; bed bug; behavior; host-seeking; movement; time-lapse photography.

Figure 1

The time-lapse photography system and other equipment used to track the behavioral movement of the bed bugs throughout the experimental arena.

Figure 2

Sample walking-path of one bed bug, within the experimental arena (91.44 × 91.44 cm), demonstrating characteristic host-seeking behavior in the (a) presence and (b) absence of host breath. Tracks began (white cross) at the harborage in the center of the arena. In both instances, the breathing tube (black dot) was located in the upper left corner of the arena. The vertical and horizontal axes are measured in centimeters.

Figure 3

Orientation response of bed bugs in the four treatment groups: females in the presence of host breath (a), females in the absence of host breath (b), males in the presence of host breath (c), males in the absence of host breath (d). The rose diagram is a circular histogram, measured in degrees, progressing clockwise from the location of the breathing tube at 0°. Dark bars radiating from the center outward indicate the weighted mean vector, α_W, of the bugs, with longer bar indicating a higher frequency of bugs and shorter bars a lower frequency of bugs. If Rayleigh test showed significant deviation from circular uniformity (P < 0.05), then the average α_W (white line) of the treatment group is shown with a 95% confidence interval.