Evidence for a residual human-host kairomone used by the bed bug, Cimex lectularius

The bed bug, Cimex lectularius L., is a human-host ectoparasite that can cause skin irritations, allergic reactions, asthma, anemia, and psychological discomfort. The recent rise in bed bug populations has been attributed to a number of mechanisms: decreased insecticide use, increased insecticide resistance, increased global trade and travel, a lack of public awareness, high treatment costs and ineffective monitoring capabilities. In this paper, we discuss evidence for an additional mechanism enabling infestation spread: the existence of a human-host kairomone that aids in host-location when the host is not present. We used a circular open-air olfactometer containing one “host-stained” cotton disk and seven unstained control disks arranged concentrically in arena. Attraction was evaluated using the following measurements: number of times a disk was selected first, time spent on each disk, number of times a bed bug returned to the disk, and mean distance of bed bug movement relative to a disk two minutes after initial contact. In each case, the bed bug showed a significant affinity for, and general movement towards the stained disk. Also, bed bugs displayed continued affinity to the area of stained disk, post-contact. When materials such as laundry, bedding, and furniture are residually stained with human secretions, these locations may place bed bugs in proximity to humans, aiding their ability to hitchhike, and increasing their dispersal chances. Also, these results provide an opportunity to improve monitoring devices, anticipate dispersal-point locations, and improve treatment strategies.