A Wolbachia coinfection in the common bed bug.

The common bed bug (Cimex lectularius) relies on an obligate mutualism with the Wolbachia strain wCle to supplement B vitamins deficient in human blood. Using metatranscriptomic and metagenomic sequencing of hospital-collected bed bugs, we found that some individuals also harbor a second strain of Wolbachia (wChem). Using publicly available data we showed that wChem is distributed in bed bugs worldwide at intermediate frequencies and may have moved recently between C. lectularius and Cimex hemipterus, the tropical bed bug, which also feeds on human hosts. We found that wChem encodes a highly expressed cifA/B operon in males and females, consistent with cytoplasmic incompatibility, a reproductive manipulation strategy used by Wolbachia to increase in frequency in host populations. Together, these results demonstrate that some bed bugs harbor a Wolbachia coinfection of a nutritional mutualist and a potentially manipulative facultative symbiont. This discovery identifies a previously hidden aspect of bed bug biology with significant implications for its evolution, spread, and potential control.