Bed bug reservoirs spread across rich and poor neighborhoods alike

Genetic analysis of nearly 200 bed bug infestations across three U.S. states shows that the insects form distinct reservoir populations in cities, but these reservoirs are not confined to socially vulnerable communities, according to a study published in Parasites & Vectors.

Researchers led by Cari D. Lewis and Warren Booth analyzed genome-wide single nucleotide polymorphism data from 195 infestations collected between 2018 and 2022 in Oklahoma, Ohio, and Illinois. Their goal was to test whether census-derived measures of social vulnerability predict the spatial distribution of genetically distinct bed bug reservoir populations across multiple urban regions.

The common bed bug, Cimex lectularius, is often associated with low socioeconomic status, but whether so-called reservoir populations are linked to socially vulnerable communities had remained unclear. To address this, the team quantified vulnerability at the census tract level using the Centers for Disease Control and Prevention Social Vulnerability Index, which covers four themes, and tested associations between genetic clusters and these themes.

The genetic results revealed clear population structure within each state. Mean genetic differentiation between clusters, measured as FST, was approximately 0.06 to 0.19, and the populations showed low heterozygosity, high inbreeding, and small effective population sizes, with a mean effective size of 3.5 to 5.5 individuals.

Multiple genetically differentiated clusters were identified within each urban region, a pattern the authors interpret as geographically diffuse reservoir populations linked through human-mediated dispersal rather than through the insects’ own movement.

The association with social vulnerability varied by state. In Oklahoma and Illinois, cluster membership was non-randomly associated with Social Vulnerability Index themes, particularly socioeconomic status and household characteristics, with statistical significance at P < 0.05. In Ohio, however, no significant associations were detected.

Importantly, the study found that bed bug clusters occurred across both high- and low-vulnerability census tracts. Reservoir populations, in other words, are not restricted to disadvantaged neighborhoods, even where some statistical association with vulnerability measures exists.

The authors conclude that fine-scale social structure shapes the spatial organization of urban bed bug populations, but that reservoir populations are not confined to socially vulnerable communities. They suggest that effective vector and pest management strategies should therefore emphasize coordinated, community-wide approaches rather than targeting disadvantaged neighborhoods alone.

The study is an open access article published on 21 October 2026, and the version shared is subject to further edits before the final Version of Record. As an observational genetic survey of infestations in three states, its findings describe patterns of association between genetic clusters and social vulnerability measures rather than causal effects, and the authors note that the influence of socioeconomic structure on indoor pests of health significance remains an area requiring further study.

Subject of Research: Population genetics of urban bed bug reservoirs and their relationship to social vulnerability

Article Title: Social vulnerability structures urban pest populations, but not reservoir occurrence

Article References: Lewis, C. D., & Booth, W. (2026). Social vulnerability structures urban pest populations, but not reservoir occurrence. Parasites & Vectors. https://doi.org/10.1186/s13071-026-07745-y

Image Credits: AI Generated

DOI: 10.1186/s13071-026-07745-y

Keywords: bed bugs, Cimex lectularius, urban ecology, population genetics, social vulnerability, Social Vulnerability Index, genetic structure, effective population size, human-mediated dispersal, pest management, Parasites & Vectors, Social