Cuticular hydrocarbon evolution in termites is ecologically structured and phylogenetically labile: a comparative analysis across caste, life type and climate

Cuticular hydrocarbon evolution in termites is ecologically structured and phylogenetically labile: a comparative analysis across caste, life type and climate | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL This is a preprint and has not been peer reviewed. Data may be preliminary. 7 April 2026 V1 Latest version Share on Cuticular hydrocarbon evolution in termites is ecologically structured and phylogenetically labile: a comparative analysis across caste, life type and climate Authors : Valeria Palma-Onetto 0000-0002-0541-0135 [email protected] and Jorge Cabrera-Riquelme 0009-0003-9492-6655 Authors Info & Affiliations https://doi.org/10.22541/au.177554016.62497846/v1 142 views 95 downloads Contents Abstract Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract Cuticular hydrocarbons (CHCs) are central to insect waterproofing and chemical communication, yet their broad evolutionary pattern in termites has not been synthesized comprehensively. Here, we present a systematic review of termite CHCs with emphasis on worker profiles, caste-level comparisons, and ecological interpretation in a phylogenetic context. 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 are broadly distributed across the termite tree, whereas unsaturated compounds are more unevenly represented and recur in multiple lineages. Genus-level synthesis further showed that dominant worker chemistry is not tightly constrained by phylogeny: methyl-alkane-dominated, olefin-dominated, and mixed profiles all occur across distantly related taxa. 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 indicated that nesting life type explained part of the worker CHC variation: drywood/enclosed wood nesters showed fewer dimethylalkanes and more frequent alkatrienes than other life types. Overall, termite CHC evolution is best interpreted as repeated lineage-specific reweighting of a shared chemical toolkit shaped by both ecology and phylogeny. Introduction Cuticular hydrocarbons (CHCs) are among the most multifunctional compounds found on the insect surface. They reduce transcuticular water loss, contribute to pathogen defense, and mediate a wide range of recognition processes, including species discrimination, nestmate recognition, caste differentiation, and reproductive signaling (Howard and Blomquist 2005; Blomquist and Bagnères 2010). In eusocial insects, CHCs are especially relevant because they operate at the interface between physiology and social organization, simultaneously preserving cuticular integrity and encoding colony-level information (Blomquist and Bagnères 2010; Menzel et al. 2019; Blomquist and Ginzel, 2021). In termites, CHC studies have historically accumulated through case-specific investigations focused on taxonomy (Haverty et al. 1988, 1997, 2000, 2005; Kaib et al. 2002), colony discrimination (Howard et al. 1978, 1982; Haverty et al. 1997), caste recognition (Howard et al. 1982; Sevala et al. 2000; Gordon et al. 2020), or fertility signaling (Liebig et al. 2009; Weil et al. 2009; Funaro et al. 2018; Mitaka and Fujita 2021); revealing striking chemical diversity. Some taxa are dominated by methyl-branched hydrocarbons, others by unsaturated compounds, and still others by more compositionally balanced mixtures (Howard et al. 1978; Howard et al. 1982; Haverty et al. 1996; Haverty et al. 1997; Haverty et al. 2000; Sevala et al. 2000; Haverty et al. 2005; Aguilera-Olivares et al. 2016). Despite this literature, termite CHCs have not been synthesized within a broad comparative framework that explicitly asks whether hydrocarbon composition follows phylogeny, caste biology, or ecology. That question has become especially timely after the comparative Blattodea study of Golian et al. (2024), which showed that chemical divergence does not track molecular phylogeny or social complexity in a simple way. Their findings are particularly relevant to termites because the basalmost extant termite, Mastotermes darwiniensis , exhibits a broad and chemically mixed profile rather than an obviously primitive or simplified one, challenging any linear view of termite chemical evolution. A second unresolved issue concerns caste differentiation. Several termite studies show that workers, soldiers, nymphs, and reproductives often share the same broad hydrocarbon repertoire, while differing in the relative abundance of particular compounds (Howard et al. 1982; Sevala et al. 2000). Other studies reveal reproductively enriched profiles or fertility-linked compounds superimposed on an otherwise shared colony background (Weil et al. 2009; Liebig et al. 2009; Funaro et al. 2018; Mitaka and Fujita 2021). Together, these observations suggest that caste-level chemical divergence may often be quantitative rather than qualitatively independent. A third issue, and one that has been underappreciated in termite CHC discussions, is the potential role of ecology. Experimental work in Cryptotermes brevis showed that temperature and relative humidity can modify cuticular hydrocarbon composition (Woodrow et al. 2000). In other insects, climatic acclimation and habitat conditions are also known to influence the relative abundance of saturated, unsaturated, and branched hydrocarbons (Gibbs and Pomonis 1995; Menzel et al. 2017; Menzel et al. 2019). This raises the possibility that termite CHCs may be shaped not only by ancestry, but also by nesting life type, microclimatic buffering, and degree of exposure to external conditions. Here, we present a systematic review of termite cuticular hydrocarbons with four objectives: i) to compile the major hydrocarbon classes reported across termites and map them in a phylogenetic context; ii) to identify dominant worker CHC regimes at the genus level; iii) to compare caste-level patterns across the literature; and iv) to quantify worker CHC composition in a subset of representative taxa and test whether life type, feeding group, and climate show exploratory associations with worker CHC profiles. Materials and Methods Systematic review design This study was conducted as a systematic review of termite cuticular hydrocarbons following the general logic of PRISMA 2020. The review focused on primary studies reporting original data on cuticular or epicuticular hydrocarbons in termites, with emphasis on worker profiles and caste-resolved comparisons. Study selection is summarized in Figure S1. Literature search strategy The literature search used combinations of general and taxon-specific terms in English, including “termite cuticular hydrocarbons”, “termite epicuticular hydrocarbons”, “termite CHC”, “termite hydrocarbon profile”, “worker hydrocarbons termites”, “caste hydrocarbons termites”, and genus-specific searches such as “ Reticulitermes hydrocarbons”, “ Coptotermes hydrocarbons”, “ Nasutitermes hydrocarbons”, “ Zootermopsis hydrocarbons”, and “ Mastotermes hydrocarbons”. Searches were complemented by backward and forward citation tracking and by screening the project database. In addition to studies explicitly focused on cuticular hydrocarbons, we also screened articles centered on termite gland chemistry when their experimental design included a control or comparison extract that allowed the cuticular hydrocarbon profile to be identified. Such studies were retained only when cuticular compounds could be distinguished clearly from glandular or other non-cuticular fractions and extracted in a form comparable to the rest of the dataset. Inclusion criteria and data extraction Studies were included when they reported original data on termite cuticular or epicuticular hydrocarbons, identified at least one hydrocarbon class from the cuticle, and provided species- or genus-level taxonomic information. We extracted family, genus, species, caste, locality, climate, feeding group, life type, hydrocarbon classes, and relative abundance data when available. Worker profiles were prioritized for interspecific comparison. In taxa without a true worker caste, pseudergates or worker-like immatures were treated as worker-equivalent only when the original study used them as the main cuticular reference. Compounds were standardized into the following classes: n-alkanes, n-alkenes, alkadienes, alkatrienes, monomethylalkanes, dimethylalkanes, trimethylalkanes, and unresolved branched hydrocarbons. The unresolved category was used only when the original study reported branched hydrocarbons without resolving them into subclasses. Qualitative and quantitative datasets Two datasets were built. The first was a qualitative matrix recording the presence or absence of major CHC classes across taxa. This matrix was used for the species-level phylogenetic summary. The second was a worker-based quantitative matrix including taxa for which relative abundance by class could be extracted or calculated. This matrix was used for the genus-level dominance summary and the comparison of selected worker profiles. The complete species-by-study matrix used to build the synthesis is provided in Table S1. Ecological variables Taxa were assigned to four nesting categories: Drywood / enclosed wood nesters, Dampwood / wood-dwelling, Subterranean / foraging, and Mound or external nest-associated foragers. Feeding group was recorded as reported in the literature. Climate was assigned from the collection locality and then collapsed into broader categories for exploratory tests. Statistical analyses For statistical analyses, we retained only species for which worker CHC profiles were sufficiently resolved and directly comparable across studies. We excluded Batista-Pereira et al. (2004) because the paper emphasized dominance patterns rather than a fully resolved class-level worker profile, Mitaka and Fujita (2021) because it focused on caste-associated compounds and did not provide a worker CHC profile comparable to the main matrix, and Nelson et al. (2001, 2008) because those studies were organized around chemical phenotypes and their correspondence with soldier defense secretions, making them valuable for qualitative interpretation but less directly comparable for species-level ecological statistics. The worker matrix was collapsed to one row per species, with class presence coded as present if reported in any qualifying worker study for that species. Fisher’s exact tests were used for binary contrasts, chi-square tests for multi-category life-type comparisons, and a Kruskal–Wallis test for class richness among life types. Study inclusion and scope of the dataset Qualitative synthesis comprised 28 studies that contributed usable information to this review. These studies documented cuticular hydrocarbons across a broad taxonomic range of termites and, in several cases, across multiple castes. Only a subset of papers provided class-resolved quantitative data suitable for direct comparison, but the broader literature consistently reported the occurrence of major hydrocarbon classes at the species level. The complete coded dataset is provided in the Supplementary Material. Across the reviewed studies, termite cuticles contained a recurrent but highly variable combination of n-alkanes, n-alkenes, alkadienes, alkatrienes, monomethylalkanes, dimethylalkanes, and trimethylalkanes. However, both the presence and relative importance of these classes varied markedly among taxa, and the level of chemical resolution differed substantially among studies. Distribution of major CHC classes across the termite phylogeny The species-level matrix showed that n-alkanes and methyl-branched hydrocarbons were broadly distributed across the termite phylogeny, whereas unsaturated compounds were more unevenly represented and occurred in distinct combinations among lineages (Fig. 1). Some taxa contained only trace or low levels of unsaturated compounds, while others showed substantial contributions of alkenes, dienes, or trienes. Likewise, dimethyl- and trimethylalkanes varied strongly across the dataset and were not restricted to a single major termite clade. At the basal end of the phylogeny, Mastotermes darwiniensis displayed one of the broadest worker profiles, including substantial fractions of saturated, unsaturated, and methyl-branched hydrocarbons. Within Archotermopsidae, Zootermopsis nevadensis and Z. angusticollis were characterized mainly by n-alkanes and branched hydrocarbons, although low or moderate unsaturated fractions were also reported depending on the species and study. In Kalotermitidae, chemical diversity was especially pronounced. Neotermes connexus combined n-alkanes, monoenes, dienes, trienes, and monomethylalkanes in a broad worker profile, whereas Neotermes mona was more strongly biased toward methyl-branched compounds. Pterotermes occidentis was dominated by n-alkanes and monomethylalkanes, while Cryptotermes brevis , C. cynocephalus , Incisitermes immigrans , and I. minor retained substantial unsaturated fractions, including alkadienes and alkatrienes. By contrast, Neotermes chilensis and Procryptotermes corniceps were more strongly enriched in saturated and unresolved branched compounds. Within Rhinotermitidae, Coptotermes formosanus , C. vastator , and C. gestroi were consistently dominated by methyl-branched hydrocarbons and showed little or no contribution from unsaturated classes. Heterotermes was chemically more heterogeneous. The Australian species treated by Watson et al. showed profiles containing different combinations of alkenes, alkadienes, alkatrienes, and methyl-branched hydrocarbons. In Reticulitermes , cuticular chemistry was consistently more complex. This was true not only for R. flavipes , R. virginicus , and R. speratus , but also for western European and Mediterranean taxa such as R. santonensis and R. lucifugus , in which n-alkanes, monoenes, methyl-branched compounds, and, in some species, dienes and trienes were all recorded. Within Termitidae, strong divergence was also evident. Nasutitermes corniger and N. ephratae were dominated by dimethylalkanes, whereas Parvitermes wolcotti showed one of the most extreme unsaturated profiles in the dataset, dominated by alkatrienes. Nasutitermes acajutlae retained a broad hydrocarbon repertoire but remained strongly biased toward unsaturated compounds. Genus-level patterns of dominant worker chemistry When worker profiles were summarized at the genus level according to their dominant hydrocarbon class, clear differences emerged across termite lineages (Fig. 2). Mastotermes was best characterized as mixed, as its worker profile contained substantial fractions of saturated, unsaturated, and methyl-branched hydrocarbons without a single overwhelmingly dominant class. Zootermopsis was predominantly methyl-alkane dominated, reflecting the strong contribution of mono- and dimethylalkanes relative to unsaturated compounds. Within Kalotermitidae, dominant chemistry varied among genera: Neotermes and Pterotermes showed profiles ranging from mixed to olefin-biased, whereas Cryptotermes and Incisitermes were more consistently associated with unsaturated-rich worker blends. In Rhinotermitidae, Coptotermes , Heterotermes , and Reticulitermes were broadly consistent with a methyl-alkane-dominated condition, although the degree of unsaturated contribution differed among genera. Within Termitidae, marked contrasts were also evident, with Nasutitermes characterized mainly by methyl-branched dominance, particularly dimethylalkanes, whereas Parvitermes was distinctly olefin dominated. Relative abundance patterns in selected worker profiles The quantitative comparison of selected worker profiles highlighted strong interspecific variation in class-level investment (Fig. 3). Mastotermes darwiniensis displayed one of the most compositionally balanced profiles, with substantial fractions of n-alkanes, n-alkenes, alkadienes, and monomethylalkanes. Zootermopsis nevadensis was dominated by n-alkanes, monomethylalkanes, and dimethylalkanes, with only low evidence of olefinic compounds in the full compound list. Within Kalotermitidae, Neotermes connexus combined n-alkanes, monoenes, dienes, trienes, and monomethylalkanes in a broad profile, whereas Neotermes mona was shifted toward monomethylalkane dominance. Pterotermes occidentis combined high proportions of n-alkanes and monomethylalkanes with a comparatively minor unsaturated fraction. Within Rhinotermitidae, Coptotermes formosanus showed one of the most polarized worker profiles, dominated almost entirely by monomethylalkanes and lacking a meaningful unsaturated component. Heterotermes sp. was also dominated by methyl-branched hydrocarbons, especially mono- and dimethylalkanes. Reticulitermes flavipes retained a more compositionally mixed worker profile in which n-alkanes, n-alkenes, and monomethylalkanes each contributed substantial fractions. Within Termitidae, Nasutitermes corniger and N. ephratae were strongly dominated by dimethylalkanes, whereas Parvitermes wolcotti differed sharply in being overwhelmingly dominated by alkatrienes. Caste-level comparisons across the reviewed literature The caste-resolved literature showed that chemical differences among castes were common, but in most cases these differences reflected changes in relative abundance rather than complete replacement of the major CHC classes (Table 1). In Reticulitermes virginicus , workers, soldiers, nymphs, and reproductives shared the same main classes, including n-alkanes, methylalkanes, dimethylalkanes, alkenes, and dienes, while caste differences were expressed primarily through proportional shifts (Howard et al. 1982). A similar pattern was reported for Zootermopsis nevadensis , in which castes shared the same general hydrocarbon repertoire, although the abundance of major compounds varied among workers and reproductive forms (Sevala et al. 2000). Comparable caste-associated quantitative differences were also reported in Coptotermes formosanus and C. gestroi . Several studies also documented compounds or profiles associated with reproductive individuals. In Zootermopsis nevadensis , actively reproductive males and females contained four polyunsaturated alkenes that were absent or detected only in trace amounts in workers and soldiers (Liebig et al. 2009). In Reticulitermes flavipes , queens and kings contained heneicosane together with other strongly royal-enriched hydrocarbons reported in association with royal recognition (Funaro et al. 2018). In Reticulitermes speratus , queens showed a markedly higher proportion of n-pentacosane than other castes within an otherwise shared CHC background (Mitaka and Fujita 2021). In Cryptotermes secundus , queens differed from workers by a profile enriched in longer-chain and more branched hydrocarbons (Weil et al. 2009). In Nasutitermes acajutlae , workers, soldiers, and alates shared the same broad hydrocarbon background, but soldiers were relatively enriched in early-eluting saturated compounds, whereas workers and alates showed higher representation of unsaturated fractions. Exploratory ecological patterns in worker CHC profiles At the species level, the strongest ecological association involved life type, not feeding group or broad climate category. In the filtered species-collapsed worker matrix, dimethylalkanes were present in only 2 of 8 drywood / enclosed wood nesters, but in 24 of 29 species representing the other life types combined. This contrast was significant in Fisher’s exact test (p = 0.0041). Alkatrienes were present in 5 of 8 drywood species but only 6 of 29 non-drywood species, also yielding a significant association (p = 0.035). When all life-type categories were compared simultaneously, the presence of dimethylalkanes differed significantly among them (χ² = 10.29, df = 3, p = 0.016), whereas alkatrienes, alkadienes, alkenes, and pooled unsaturated compounds did not. Class richness also did not differ among life types (Kruskal–Wallis p = 0.795), indicating that the ecological pattern was driven by the distribution of particular hydrocarbon classes rather than by overall chemical richness. Broad climate category produced weaker and less stable associations. After climates were collapsed into a tropical-lowland versus non-tropical contrast, none of the major class-presence tests remained significant at p < 0.05. Feeding group was not informative because most taxa in the dataset were wood feeders and only a small number represented other feeding syndromes. Discussion The present synthesis shows that termite CHC evolution is chemically diverse, phylogenetically labile, and at least partly structured by ecology. Even though the literature remains uneven in taxonomic coverage and analytical depth, the available evidence does not support a simple model in which worker CHC composition follows phylogeny in a conservative or linear manner. The species-level matrix reveals recurring combinations of saturated, unsaturated, and methyl-branched hydrocarbons in different parts of the termite tree, the genus-level summary shows that dominant worker chemistry is not confined to single higher lineages, and the quantitative comparison demonstrates that distantly related taxa can converge on similarly polarized profiles while closer relatives may diverge sharply. Because Mastotermes is the basalmost living termite, a chemically narrow or obviously primitive profile might have been expected. Instead, Mastotermes darwiniensis shows one of the broadest known worker blends, with substantial fractions of n-alkanes, n-alkenes, alkadienes, and monomethylalkanes. This result does not fit a model in which early termite chemistry was chemically reduced, and later lineages became progressively more elaborate. Rather, it suggests that the ancestral termite condition may already have been chemically versatile, and that subsequent evolution involved repeated shifts in the relative weighting of pre-existing hydrocarbon classes. This interpretation is consistent with the broader Blattodea-scale results of Golian et al. (2024), who also found that chemical divergence does not mirror phylogeny or social complexity in a straightforward way. The more polarized profiles observed in several extant termites are therefore better interpreted as lineage-specific specializations than as endpoints of a single directional trend. Coptotermes formosanus appears as a lineage strongly shifted toward monomethylalkane dominance with little or no detectable unsaturated contribution, whereas Parvitermes wolcotti represents a highly unsaturated worker condition dominated by alkatrienes. Between these poles lie taxa such as Reticulitermes flavipes , Neotermes connexus , and Mastotermes darwiniensis , in which substantial contributions from multiple classes are retained. This range of profiles is more consistent with repeated lineage-specific reweighting of a shared chemical toolkit than with repeated replacement of one chemical regime by another. The genus-level patterns reinforce the same point. Kalotermitidae do not conform to a single chemical syndrome. Some genera, such as Cryptotermes and Incisitermes , are frequently rich in unsaturated compounds, whereas others, such as Pterotermes , are dominated by saturated and monomethyl-branched fractions. Termitidae are similarly heterogeneous, including dimethyl-rich Nasutitermes species and highly unsaturated Parvitermes . Even within Rhinotermitidae, the contrast between strongly methyl-branched Coptotermes and the more compositionally mixed Reticulitermes shows that substantial divergence may arise within the same higher lineage. These patterns make it difficult to interpret CHC evolution as primarily constrained by phylogeny alone. The ecological analyses suggest that nesting biology captures part of this variation more effectively than broad climatic categories. Drywood / enclosed wood nesters were significantly less likely to contain dimethylalkanes and showed a higher frequency of alkatrienes than the other life types, whereas overall hydrocarbon class richness did not differ among life types. This indicates that the ecological signal lies not in total chemical complexity, but in the differential representation of particular classes. In practical terms, drywood termites appear to occupy a distinctive region of CHC compositional space rather than simply having richer or poorer worker profiles. That result is biologically plausible. Drywood termites live within relatively buffered wooden substrates, whereas subterranean, dampwood, and mound-associated termites are generally more exposed to soil contact, external humidity gradients, or broader foraging environments. Nest architecture, substrate moisture, and the extent of environmental exposure are therefore likely to influence the selective balance between waterproofing and communication. Straight-chain n-alkanes have higher melting temperatures and pack more tightly than unsaturated or methyl-branched hydrocarbons, properties expected to increase cuticular viscosity and reduce permeability (Gibbs and Pomonis 1995; Menzel et al. 2019). By contrast, methyl branching and unsaturation disrupt packing and lower melting temperature, thereby changing cuticular performance as well as the potential signal space of the blend (Gibbs and Pomonis 1995; Blomquist and Bagnères 2010; Menzel et al. 2019). Unsaturated hydrocarbons may also be more chemically labile under environmental exposure (Sprenger et al. 2020). Within this framework, repeated shifts among n-alkane-rich, dimethyl-rich, and alkatriene-rich profiles may reflect different balances between waterproofing requirements and communication demands across termite life types. The climatic literature supports this interpretation, even though the present dataset did not recover a strong climate-only signal. In Cryptotermes brevis , Woodrow et al. (2000) showed experimentally that both temperature and relative humidity can modify cuticular hydrocarbon composition, with temperature exerting particularly strong effects on the abundance of individual compounds. Similar environmentally induced shifts are known from other insects, where temperature, humidity, and desiccation regime influence the balance of saturated, unsaturated, and branched hydrocarbons (Menzel et al. 2017; Menzel et al. 2019). The weak climate signal in the current analysis should therefore not be interpreted as evidence that climate is irrelevant. More likely, broad regional climate categories are simply too coarse to capture the conditions actually experienced by the termite cuticle. From that perspective, life type may currently be acting as the better biological summary of climatic exposure because it integrates macroclimate, nest buffering, substrate, and the degree of contact with the external environment. The caste-level literature adds a second important layer to this picture. Across the reviewed studies, workers, soldiers, nymphs, and reproductives usually share the same major hydrocarbon classes, and caste differences most often arise through shifts in relative abundance rather than through complete chemical turnover. This is particularly clear in Reticulitermes virginicus and Zootermopsis nevadensis , and it is broadly consistent with the patterns reported for Nasutitermes acajutlae , Coptotermes formosanus , and C. gestroi (Howard et al. 1982; Haverty et al. 1996; Sevala et al. 2000; Gordon et al. 2020). These results suggest that termite caste chemistry is generally built on a shared colony-level background rather than on wholly caste-exclusive chemical repertoires. At the same time, reproductives in several lineages also show additional caste-associated compounds or strongly biased reproductive profiles. This is evident in Zootermopsis nevadensis , where active reproductives contain polyunsaturated compounds absent or nearly absent from workers and soldiers (Liebig et al. 2009), in Reticulitermes flavipes , where royal recognition is associated with heneicosane and other royal-enriched hydrocarbons (Funaro et al. 2018), and in Cryptotermes secundus , where queens differ from workers by enrichment in longer-chain and more strongly branched compounds (Weil et al. 2009). These cases indicate that baseline worker chemistry and caste-specific signaling do not necessarily evolve along the same axis. A lineage may remain methyl-branched dominated at the worker level while still deploying unsaturated or caste-biased compounds in a reproductive context. Taken together, the evidence supports a view of termite CHC evolution as dynamic, repeated, and ecologically structured. The broad profile of Mastotermes suggests an ancestrally versatile condition. The repeated occurrence of methyl-alkane-dominated and olefin-dominated worker profiles across different termite lineages indicates recurrent lineage-specific specialization. The caste literature shows that these macroevolutionary shifts are layered on top of a generally shared colony chemical background, within which reproductive and, in some cases, soldier-associated compounds may arise through quantitative shifts or the addition of caste-associated components. Finally, the exploratory ecological analyses indicate that nesting life type, and especially the contrast between drywood / enclosed wood nesters and the other termite life types, captures a meaningful fraction of the variation in worker CHC composition. Future progress will depend on denser sampling of basal lineages, especially Stolotermitidae, more consistent caste-resolved quantification, and a more mechanistic treatment of ecological exposure and nest microclimate. 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Cuticular hydrocarbons as chemotaxonomic characters for Nasutitermes corniger (Motschulsky) and N. ephratae (Holmgren) (Isoptera: Termitidae). Annals of the Entomological Society of America, 81, 395-399. https://doi.org/10.1093/aesa/81.3.395 Jenkins, T. M., Haverty, M. I., Basten, C. J., Nelson, L. J., Page, M., & Forschler, B. T. (2000). Correlation of mitochondrial haplotypes with cuticular hydrocarbon phenotypes of sympatric Reticulitermes species from the southeastern United States. Journal of Chemical Ecology, 26, 1525-1542. https://doi.org/10.1023/A:1005548111591 Kaib, M., Franke, S., Francke, W., & Brandl, R. (2002). Cuticular hydrocarbons in a termite: Phenotypes and a neighbour-stranger effect. Physiological Entomology, 27(3), 189-198. https://doi.org/10.1046/j.1365-3032.2002.00292.x Kaib, M., Jmhasly, P., Wilfert, L., Durka, W., Franke, S., Francke, W., Leuthold, R. H., & Brandl, R. (2004). Cuticular hydrocarbons and aggression in the termite Macrotermes subhyalinus. 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I. (2000). Modification of cuticular hydrocarbons of Cryptotermes brevis (Isoptera: Kalotermitidae) in response to temperature and relative humidity. Environmental Entomology, 29, 1100-1107. https://doi.org/10.1603/0046-225X-29.6.1100 Figure legendsBottom of Form Figure 1. Species-level phylogeny of termites showing the presence or absence of major worker CHC classes. Symbols indicate the occurrence of n-alkanes, n-alkenes, alkadienes, alkatrienes, monomethylalkanes, dimethylalkanes, trimethylalkanes, and unresolved branched hydrocarbons. Worker profiles were used whenever available; worker-equivalent immature stages were used only in taxa lacking a true worker caste. Figure 2. Genus-level summary of dominant worker CHC chemistry across termites. Genera were classified as methyl-alkane dominated, olefin dominated, or mixed according to the dominant worker compound class reported in the literature. Figure 3. Relative abundance of major CHC classes in selected termite workers. Profiles are shown for available termite species. Bars represent relative proportions of n-alkanes, n-alkenes, alkadienes, alkatrienes, monomethylalkanes, dimethylalkanes, trimethylalkanes, and others. Tables Table 1. Qualitative caste-level CHC patterns reported in termites. Studies included here summarize caste-associated patterns for descriptive comparison and were not necessarily part of the filtered worker dataset used for the ecological statistics. Reticulitermes virginicus X X Howard et al. (1982) Zootermopsis nevadensis X X X Sevala et al. (2000); Liebig et al. (2009) Nasutitermes acajutlae X X Haverty et al. (1996) Reticulitermes flavipes X X X Funaro et al. (2018) Cryptotermes secundus X X X Weil et al. (2009) Coptotermes formosanus X X Haverty et al. (1996) Coptotermes gestroi X X Gordon et al. (2020) Reticulitermes speratus X X X Mitaka and Fujita (2021) Information & Authors Information Version history V1 Version 1 07 April 2026 Copyright This work is licensed under a Non Exclusive No Reuse License. Keywords comparative description evolutionary ecology invertebrate laboratory natural history statistical terrestrial theoretical Authors Affiliations Valeria Palma-Onetto 0000-0002-0541-0135 [email protected] Universidad Técnica Federico Santa María View all articles by this author Jorge Cabrera-Riquelme 0009-0003-9492-6655 Universidade Federal do ABC - Campus Sao Bernardo do Campo View all articles by this author Metrics & Citations Metrics Article Usage 142 views 95 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Valeria Palma-Onetto, Jorge Cabrera-Riquelme. Cuticular hydrocarbon evolution in termites is ecologically structured and phylogenetically labile: a comparative analysis across caste, life type and climate. Authorea . 07 April 2026. 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