Evolution Of The Common Bed Bug, Cimex lectularius, In The Urban Environment: From The Birth Of Civilization To Global Dominance

Using genomic tools, it is now possible to investigate factors that influence demography, connectivity, and genomic diversity, to understand how organisms are adapting and evolving in response to the multitude of selective pressures that exist within cities and urban environments. The common bed bug, Cimex lectularius L., is proving to be an excellent model system with which to investigate urban evolution. It is a species with a long association with humans; the earliest records dating back to Pharaonic Egypt. Ancestrally, an ectoparasite of bats, a host transition to hominins occurred approximately 245,000 years ago, resulting in two extant lineages that do not appear to experience gene flow: one associated with bats and distributed across Europe and the Middle East, and the other with humans that now exhibits a near-global distribution. Despite the introduction of DDT in the 1940’s, which single-handedly almost eliminated the species from modernized countries, populations of the human-associated lineage resistant to this and other broad-spectrum insecticides soon appeared and by the late 1990’s the species was resurging across multiple continents at an alarming rate. Here, we discuss the evolutionary history of the common bed bug and the genetic characteristics of populations that have enabled it to become a prominent pest of the indoor environment.