Comparative Patterns of Cuticular Hydrocarbon Diversity in Termites Across Castes and Nesting Life Types.

Cuticular hydrocarbons (CHCs) are central to insect waterproofing and chemical communication, yet their diversity and comparative distribution in termites have not been synthesized comprehensively. Here, we present a systematic review of termite CHCs with emphasis on worker profiles, caste-level comparisons, and descriptive ecological interpretation. The qualitative synthesis included 28 studies, whereas the filtered statistical dataset comprised 37 worker profiles representing 37 species. Across the reviewed literature, termite cuticles contained a recurrent but variable combination of n-alkanes, n-alkenes, alkadienes, alkatrienes, mono-, di-, and trimethylalkanes. Species-level mapping showed that saturated and methyl-branched hydrocarbons were broadly distributed across the sampled taxa, whereas unsaturated compounds were more unevenly represented across the dataset. Genus-level synthesis showed that methyl-alkane-dominated, olefin-dominated, and mixed worker profiles occur in different higher taxonomic groups within the sampled dataset. Quantitative comparison of selected worker profiles highlighted broad chemistry in Mastotermes darwiniensis, strong methyl-branched dominance in Coptotermes formosanus, dimethyl-rich profiles in Nasutitermes corniger and N. ephratae, and marked alkatriene dominance in Parvitermes wolcotti. Caste-resolved studies showed that workers, soldiers, nymphs, and reproductives usually share the same broad CHC classes, with caste differentiation arising mainly through quantitative shifts, although reproductives in some taxa also express caste-associated compounds. Exploratory ecological analyses identified associations between nesting life type and worker CHC composition: drywood/enclosed wood nesters showed fewer dimethylalkanes and more frequent alkatrienes than other life types; but these patterns could not be separated from broad family-level phylogenetic structure. Overall, the available evidence suggests that termite CHC diversity reflects variation in the relative representation of a recurring chemical toolkit, with exploratory associations between worker CHC composition and nesting life type. Because the current dataset is limited and phylogenetic signal was not formally tested, these interpretations should be considered exploratory.