Pest Management Professional • November 2022 • Pest Trends

Entomologists from the University of Kentucky (UK) College of Agriculture, Food and Environment have learned that bed bugs produce large amounts of histamine that might pose risks to humans. The study results were published in a recent edition of the Journal of Medical Entomology.

Histamine is a chemical compound the human body naturally produces that may cause inflammation and alert the immune system of any threats. Normal reactions to histamine production include allergic reactions, with side effects like rashes or respiratory problems. A previous study showed links between excess histamine, especially in patients with a histamine intolerance, and health effects such as headaches, gastrointestinal issues, irregular heart rate and asthma.

Dr. Sudip Gaire, a post-doctoral scholar in the UK Department of Entomology, and Dr. Zach DeVries, an assistant professor of entomology, led the study looking at histamine excretion levels of Cimex lectularius across the bugs’ life stages, different populations and varying lengths of time. The Lexington, Ky.-based team also collaborated with scientists from North Carolina State University on the project.

The researchers found that a single bed bug is capable of producing more than 50 micrograms of histamine in just one week. In a hypothetical infestation of 1,000 bed bugs, the bugs could produce up to 40 milligrams in a week. That adds up to more than 2 grams of histamine per year — without even considering natural population growth, or the larger infestations that often happen in the real world.

“That’s an amount you can actually see, and we don’t see that with any other containment,” Dr. DeVries said. “When we talk about pesticides, allergens — any other thing in our home that some invading organism is producing — it’s always on microscopic levels, not something where you could actually hold it in your hand.”

The researchers also found that blood-fed bed bugs produced “significantly higher” amounts of histamine compared to the saline-fed and starved groups.

While the specific health impacts of histamine produced outside of the human body are as of yet unknown, the team suspects bed bugs’ high level of histamine excretion may have negative clinical effects. The effects of such close, often direct, exposure to histamine, commonly seen in bed bug infestations, are also unknown, Dr. DeVries said.

The team plans to continue researching histamine distribution, bed bug histamine production mechanisms, the clinical relevance of histamine, and mitigation strategies in homes. Dr. DeVries received funding for the study through his 2019 National Institute of Health Director’s Early Independence Award, which will fund similar, future studies through 2024.

DID YOU KNOW?

A new study from Washington State University finds that changing weather patterns could increase suitable habitat for the brown marmorated stink bug in the U.S. by 70 percent.

A University of California – Riverside-led research team discovered the combination of carbon dioxide plus two chemicals, 2-ketoglutaric and lactic acids, elicits a scent that causes a mosquito to locate and land on its victim. The chemical mix also encourages probing, which is the use of piercing mouthparts to find blood.