Plasticity in desiccation resistance and cuticular hydrocarbon production in subterranean termites

Cuticular hydrocarbons (CHCs), synthesized in oenocytes and transported to the cuticle, serve dual functions in insects—preventing water loss and facilitating chemical communication. Composed mainly of alkanes, alkenes, and methyl-branched alkanes (21–50 carbons), CHCs form a waxy, hydrophobic barrier. While the presence of double bonds and methyl branches facilitates communication, linear alkanes are more effective in desiccation resistance. Despite their known roles, the specific contribution of CHCs to termite desiccation resistance remains poorly understood. Subterranean termites, key decomposers in warm regions, face environmental challenges from varying soil moisture and temperature. We examined acclimation responses in two species, Coptotermes formosanus and C. gestroi, under three soil moisture levels (5%, 15%, 25%) and two temperatures (20°C and 30°C). Desiccation resistance of worker termites was determined by their survival time under extreme desiccation (≤ 1% relative humidity at 27°C). Termites from 25% moisture treatments showed significantly lower survival than those from 5% and 15%, and individuals from 30°C survived longer than those from 20°C. In addition, GC-MS analysis revealed that the quantitative compositions of CHCs varied with changes in soil moisture and temperature. These results suggest that subterranean termites adjust their CHC profiles in response to environmental conditions, enhancing their desiccation resistance and adaptability.