The extension of internal humidity levels beyond the soil surface facilitates mound expansion in Macrotermes

Paul M. Bardunias, Daniel S. Calovi, Nicole Carey, Rupert Soar, J. Scott Turner, Radhika Nagpal, Justin Werfel

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Termites in the genus Macrotermes construct large-scale soil mounds above their nests. The classic explanation for how termites coordinate their labour to build the mound, based on a putative cement pheromone, has recently been called into question. Here, we present evidence for an alternate interpretation based on sensing humidity. The high humidity characteristic of the mound's internal environment extends a short distance into the low-humidity external world, in a 'bubble' that can be disrupted by external factors like wind. Termites transport more soil mass into on-mound reservoirs when shielded from water loss through evaporation, and into experimental arenas when relative humidity is held at a high value. These results suggest that the interface between internal and external conditions may serve as a template for mound expansion, with workers moving freely within a zone of high humidity and depositing soil at its edge. Such deposition of additional moist soil will increase local humidity, in a feedback loop allowing the 'interior' zone to progress further outward and lead to mound expansion.

Original languageEnglish (US)
Article number20200894
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1930
StatePublished - Jul 8 2020
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Immunology and Microbiology
  • General Environmental Science
  • General Biochemistry, Genetics and Molecular Biology
  • General Agricultural and Biological Sciences


  • Macrotermes
  • airflow
  • construction
  • humidity
  • template
  • termite


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