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1. Protection against desiccation and chemical communication are two fundamental functions of cuticular hydrocarbons (CHCs) in insects. In the parasitoid jewel wasp Nasonia vitripennis (Walker), characterised by a cosmopolitan distribution through largely different environments, CHCs function as universally recognised female sex pheromones. However, CHC uniformity as basis for sexual recognition may conflict with the desiccation protection function, expected to display considerable flexibility through adaptation to different environmental conditions. 2. We compared male and female CHC profiles of N. vitripennis across a wide latitudinal gradient in Europe and correlated their CHC variation with climatic factors associated with desiccation. Additionally, we tested male mate discrimination behaviour between populations to detect potential variations in female sexual attractiveness. 3. Results did not conform to the general expectation that longer, straight‐chain CHCs occur in higher proportions in warmer and drier climates. Instead, unexpected environmental correlations of intermediate chain‐length CHCs (C31) were found exclusively in females, potentially reflecting the different life histories of the sexes in N. vitripennis. 4. Furthermore, we found no indication of population‐specific male mate preference, confirming the stability of female sexual attractiveness, likely conveyed through their CHC profiles. C31 mono‐ and C33 di‐methyl‐branched alkanes were consistently and most strongly associated with sexual dimorphism, suggesting their potential role in encoding the female‐specific sexual signalling function. 5. Our study sheds light on how both adaptive flexibility and conserved sexual attractiveness can potentially be integrated and encoded in CHC profiles of N. vitripennis females across a wide distribution range in Europe. [ABSTRACT FROM AUTHOR]

Keywords: chemical communication; insights; olfactory signaling; infochemicals; semiochemicals; Germany; intraspecific; interspecific; pheromones; sexual communication; parasitoids; neuroecology EN chemical communication insights olfactory signaling infochemicals semiochemicals Germany intraspecific interspecific pheromones sexual communication parasitoids neuroecology 286 288 3 03/22/22 20220401 NES 220401 The topics of insect chemical communication in this issue can be subdivided into intra- and interspecific signaling mechanisms. 22 Mair MM & Ruther J (2019) Chemical ecology of the parasitoid wasp genus Nasonia (Hymenoptera: Pteromalidae). Another identifies a parasitoid-derived mortality-inducing protein, and discusses its potential for biological pest control. Males of the parasitoid wasp I Muscidifurax raptorellus i Kogan & Legner (Hymenoptera: Pteromalidae) start their courtship of a potential female mating partner with conspicuous wing fanning behavior. [Extracted from the article]

Sex pheromones play a pivotal role in the communication of many sexually reproducing organisms. Accordingly, speciation is often accompanied by pheromone diversification enabling proper mate finding and recognition. Current theory implies that chemical signals are under stabilizing selection by the receivers who thereby maintain the integrity of the signals. How the tremendous diversity of sex pheromones seen today evolved is poorly understood. Here we unravel the genetics of a newly evolved pheromone phenotype in wasps and present results from behavioural experiments indicating how the evolution of a new pheromone component occurred in an established sender-receiver system. We show that male Nasonia vitripennis evolved an additional pheromone compound differing only in its stereochemistry from a pre-existing one. Comparative behavioural studies show that conspecific females responded neutrally to the new pheromone phenotype when it evolved. Genetic mapping and gene knockdown show that a cluster of three closely linked genes accounts for the ability to produce this new pheromone phenotype. Our data suggest that new pheromone compounds can persist in a sender's population, without being selected against by the receiver and without the receiver having a pre-existing preference for the new pheromone phenotype, by initially remaining unperceived. Our results thus contribute valuable new insights into the evolutionary mechanisms underlying the diversification of sex pheromones. Furthermore, they indicate that the genetic basis of new pheromone compounds can be simple, allowing them to persist long enough in a population for receivers to evolve chemosensory adaptations for their exploitation. [ABSTRACT FROM AUTHOR]

Insects rely on olfaction to guide a wide range of adaptive behaviors, including mate and food localization, mate choice, oviposition site selection, kin recognition, and predator avoidance. 1 In nocturnal insects, such as moths 2 and cockroaches, 3 mate finding is stimulated predominantly by long-range species-specific sex pheromones, typically emitted by females. During courtship, at close range, males in most moth species emit a blend of pheromone compounds from an everted, often large, pheromone gland. While long-distance communication with sex pheromones has been remarkably well characterized in thousands of moth species, 2,4 close-range chemosensory sexual communication remains poorly understood. We reveal that in the moth Chloridea virescens , the male pheromone consists of three distinct classes of compounds: de novo biosynthesized alcohols, aldehydes, acetates, and carboxylic acids that resemble the female's emissions; newly identified compounds that are unique to the male pheromone, such as aliphatic polyunsaturated hydrocarbons; and sequestered plant secondary compounds and hormone derivatives, including methyl salicylate (MeSA). Thus, males employ a mosaic pheromone blend of disparate origins that may serve multiple functions during courtship. We show that two olfactory receptors in female antennae are tuned to MeSA, which facilitates female acceptance of the male. Because MeSA is emitted by plants attacked by pathogens and herbivores, 5 the chemosensory system of female moths was likely already tuned to this plant volatile, and males appear to exploit the female's preadapted sensory bias. Interestingly, while female moths (largely nocturnal) and butterflies (diurnal) diverged in their use of sensory modalities in sexual communication, 6 MeSA is used by males of both lineages. [Display omitted] • The courtship pheromone of male Chloridea virescens moths was re-examined • The pheromone constitutes a mosaic of type I, type II, and plant-derived compounds • Methyl salicylate (MeSA) is an aphrodisiac that improves mating success • Two olfactory receptors contribute to high olfactory sensitivity of females to MeSA Liu et al. identify novel chemicals, including methyl salicylate (MeSA), that male moths use during courtship to increase mating success. Two olfactory receptors on female antennae detect MeSA. The male sex pheromone is a mosaic blend that includes fatty acid derivatives, unsaturated hydrocarbons, and sequestered plant-derived compounds. [ABSTRACT FROM AUTHOR]