Common bed bugs possess a robust ability to produce histamine

Common bed bugs (Cimex lectularius L.) are hematophagous pests that lives in close proximity to humans. Following a blood meal, they deposit fecal material in the indoor environment. Their fecal material contains a variety of components, including the pivotal mammalian immune modulator histamine. Recently, histamine was shown to be present in high concentrations in household dust from homes infested with bed bugs. Bed bugs clearly contribute histamine to the indoor environment, but it is unclear what life stages are responsible, how production varies among populations, and how much histamine bed bugs produce over time. To better understand histamine production, we collected and analyzed bed bug fecal material from different life stages, populations, and times after feeding using gas chromatography-mass spectrometry. Our analysis showed significant variation of histamine production among life stages. The highest histamine amount can be produced by a mated females (~15 µg/day/bug), whereas the first instar nymphs had the lowest amount (< 0.5 µg/day/bug). We also found significant differences in histamine production among bed bug populations, ranging from ~2.5 to 5 µg/bug/day for adult males. Lastly, we found histamine production continued up to 21 days post-feeding, with the highest amount of histamine produced three days after a blood meal (8.5 µg/bug/day). This work demonstrates bed bugs possess a robust ability to produce histamine across life stages, populations, and time after feeding, and the results will be used to better understand the health risks associated with histamine production and potential mitigation strategies.