Microbes help tell how old termite pellets are ^{CEFR B2}

Detecting whether termite pellets are fresh or old is important to decide if a colony is active and whether treatment is needed. Earlier approaches—testing hydrocarbons or watching pellet colour—required expensive equipment or were unreliable because colour depends on diet. A recent study from the University of California, Riverside, published in the Journal of Economic Entomology, describes a different approach that uses the pellet microbiome as a time marker.

Termites host diverse microbes, including bacteria and protists, that help digest wood and are expelled in pellets. Many of these microbes are anaerobic and die quickly when exposed to air; as their cells break down, microbial DNA degrades. The researchers say this decaying DNA creates a fading signature that records how long pellets have been exposed.

Nick Poulos collected drywood termites and fed them natural hardwood and Douglas fir, the latter chosen because it is the most common wood used for house framing. The team sampled pellets when fresh and after three months, six months and one year. Using quantitative PCR to measure bacterial DNA, they observed about a 190-fold decline by 12 months for natural hardwood pellets and a 184-fold decline for Douglas fir-derived pellets, with most of the decrease occurring by six months.

The study also found a shift in bacterial composition: obligate anaerobes dropped and disappeared over time, while oxygen-tolerant bacteria became more common. The researchers hope to collaborate with scientists and engineers to build sensors that detect these bacterial signals—possibly a lateral flow assay similar to a COVID-19 test—so pest professionals can rapidly estimate infestation age and avoid unnecessary chemical treatments.

• Rapid on-site age estimate
• Reduce unnecessary treatments
• Help pest professionals decide response