Eusocial insects use cuticular hydrocarbons as components of pheromones that mediate social behaviours, such as caste and nestmate recognition, and regulation of reproduction. In ants such as Harpegnathos saltator, the queen produces a pheromone which suppresses the development of workers’ ovaries and if she is removed, workers can transition to a reproductive state known as gamergate. Here we functionally characterize a subfamily of odorant receptors (Ors) with a nine-exon gene structure that have undergone a massive expansion in ants and other eusocial insects. We deorphanize 22 representative members and find they can detect cuticular hydrocarbons from different ant castes, with one (HsOr263) that responds strongly to gamergate extract and a candidate queen pheromone component. After systematic testing with a diverse panel of hydrocarbons, we find that most Harpegnathos saltator Ors are narrowly tuned, suggesting that several receptors must contribute to detection and discrimination of different cuticular hydrocarbons important in mediating eusocial behaviour.

The cuticles of springtails are extremely wear‐ and friction‐resistant, super‐hydrophobic, non‐fouling, and self‐cleaning. As such, the chemistry of the lipids covering these cuticles is of great interest as a model for biomimetic super‐hydrophobic surfaces, although only few of these lipids have been structurally elucidated. Hypogastrura viatica, a surface‐dwelling springtail, produces highly branched tetraterpene hydrocarbons with an unprecedented [6+2]‐terpene connectivity as components of the epicuticular lipid layer. The structure of the major lipid component, viaticene A, was elucidated through isolation, spectroscopic analysis, chemical derivatization, synthesis, as well as stereochemical analysis of the core unit obtained from ozonolysis of the isolated lipid. Viaticenes A and B represent a new class of irregular tetraterpenoid natural products.

Although the effects of stereochemistry have been studied extensively for volatile insect pheromones, little is known about the effects of chirality in the nonvolatile methyl-branched hydrocarbons (MBCHs) used by many insects as contact pheromones. MBCHs generally contain one or more chiral centers and so two or more stereoisomeric forms are possible for each structure. However, it is not known whether insects biosynthesize these molecules in high stereoisomeric purity, nor is it known whether insects can distinguish the different stereoisomeric forms of MBCHs. This knowledge gap is due in part to the lack of methods for isolating individual MBCHs from the complex cuticular hydrocarbon (CHC) blends of insects, as well as the difficulty in determining the absolute configurations of the isolated MBCHs. To address these deficiencies, we report a straightforward method for the isolation of individual cuticular hydrocarbons from the complex CHC blend. The method was used to isolate 36 pure MBCHs from 20 species in nine insect orders. The absolute stereochemistries of the purified MBCHs then were determined by digital polarimetry. The absolute configurations of all of the isolated MBCHs were determined to be (R) by comparison with a library of synthesized, enantiomerically pure standards, suggesting that the biosynthetic pathways used to construct MBCHs are highly conserved within the Insecta. The development of a straightforward method for isolation of specific CHCs will enable determination of their functional roles by providing pure compounds for bioassays.T he use of chemical signals is highly developed within insects, with semiochemicals mediating a wide variety of inter-and intraspecific behaviors. Volatile pheromones, such as sex and aggregation pheromones, are the most well-known types, but insects also use nonvolatile cuticular lipids as contact pheromones (1-4). The cuticular lipids consist of a complex blend of n-and methyl-branched alkanes, alkenes, and lesser amounts of more polar compounds such as esters and alcohols. The lipid layer acts primarily as a waterproofing barrier (5), but individual lipid components have evolved secondary roles as signals that mediate a variety of behaviors and physiological changes (1, 2, 6). For example, solitary insects use cuticular hydrocarbons (CHCs) to identify the species and sex of mates (7, 8) whereas, in social insects, CHCs mediate identification of nestmates (9, 10), recognition of castes, and task allocation within the colony (11). Social insect queens also use CHCs to signal fecundity and dominance status within the colony, inhibiting development of workers into reproductives (12)(13)(14).Determining the roles of specific CHCs as signals has been hindered by three interlinked problems. First, CHCs typically consist of a large number of compounds, which can be difficult to isolate in pure form to test their bioactivities. Specifically, CHCs have very similar polarity and so are not separable by liquid chromatography on silica gel or other polar chromatographic m...

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