Microbes help tell how old termite pellets are ^{CEFR B1}

Earlier methods to estimate pellet age tested for hydrocarbons or relied on colour changes, but these approaches needed expensive machines or were unreliable because pellet colour varies with diet. A new study from the University of California, Riverside and published in the Journal of Economic Entomology describes an alternative method based on the microbes in termite excrement.

Termites carry diverse microbial communities that help digest wood and are released with pellets. Many of these microbes are anaerobic and do not survive long in air; as their cells die, DNA degrades and provides a fading signature that indicates how long pellets have been exposed.

Nick Poulos collected drywood termites and fed them natural hardwood and Douglas fir, the latter because it is common for house framing. Pellets were sampled fresh and after three months, six months and one year. Using quantitative PCR, the team measured bacterial DNA and found a nearly 190-fold decline by 12 months for natural hardwood pellets and a 184-fold decline for Douglas fir pellets, with much of the drop by six months.

The researchers also tracked which bacteria were present: anaerobic bacteria became less abundant and then disappeared, while oxygen-preferring bacteria increased as pellets aged. The team hopes to work with engineers to build sensors, such as a lateral flow assay like a COVID-19 test, to indicate infestation age and help avoid unnecessary chemical treatments.