Cuticular hydrocarbons and desiccation resistance in subterranean termites

Subterranean termites are soil-dwelling insects living in social colonies composed of queens, kings, workers, and soldiers. The caste system is established through developmental plasticity of individuals exposed to different social cues. Water availability, including soil moisture and atmospheric humidity, is essential for the survival and dispersal of subterranean termites, and termite castes face different environmental stresses due to the division of labor. However, little is known if desiccation resistance differ among castes or if the response varies upon environmental changes. In the Formosan subterranean termite, Coptotermes formosanus, we examined the changes in desiccation resistance and cuticular hydrocarbons (CHCs) profiles across castes (developmental plasticity) and in response to environmental conditions (acclimation effects). The results showed that termite castes had different levels of desiccation tolerance and quantitative differences in CHCs. Additionally, workers exhibited plastic responses in desiccation resistance to soil moisture and temperature changes. Increased desiccation resistance and upregulated CHC peaks were observed when workers were acclimated to lower moisture or higher temperature. The results suggest that CHC plasticity plays a role in the acclimation responses of subterranean termites to drier and warmer environments.