How many bedbugs are in diapause? - briefly
Only a small fraction of a bed‑bug population—generally under 5 %—enters diapause when temperature and photoperiod become unfavorable. The precise number varies with local conditions and cannot be predicted exactly.
How many bedbugs are in diapause? - in detail
Research on Cimex lectularius indicates that only a minority of individuals enter a dormant phase under unfavorable conditions. Field surveys in temperate regions report diapause frequencies ranging from 5 % to 20 % of the population during winter months, depending on temperature, photoperiod, and host availability. Laboratory experiments that expose cohorts to 10 °C and a 12‑hour light cycle show that approximately 12 % of nymphs and 8 % of adult females arrest development after the fourth instar.
Key factors influencing the proportion of dormant individuals:
- Sustained low ambient temperature (below 12 °C) triggers hormonal changes that suppress molting.
- Shortened day length (≤ 10 h) reinforces the temperature signal.
- Limited blood‑meal opportunities increase the likelihood of entering dormancy.
Methods used to quantify dormant bedbugs include:
- Direct counting under a stereomicroscope after sorting specimens by developmental stage and physiological state.
- Molecular markers of diapause (elevated expression of the diapause‑associated protein DAP‑1) measured by quantitative PCR.
- Respirometric assays that detect reduced metabolic rates characteristic of dormancy.
Recent longitudinal studies in multi‑unit housing show that the absolute number of dormant insects can rise to several hundred per infested apartment when winter conditions persist for more than two months. In contrast, in warmer climates where temperatures rarely fall below 15 °C, diapause is rarely observed, and counts typically remain below 1 % of the total population.
Overall, the proportion of bedbugs in a dormant state is modest and highly dependent on environmental cues, with documented ranges from a few individuals to a few hundred per infestation under severe winter conditions.