Despite previous doubts about the origin of terpenes in springtails, a deep bioinformatic analysis of the genomes of 26 springtails surprisingly revealed the presence of many genes coding for microbial-type terpene synthases. Five candidate enzymes from Sinella curviseta representing different branches of a phylogenetic tree were selected for investigation, four of which were active in in vitro incubations with an enzyme-dependent substrate selectivity ranging from farnesyl (FPP) to geranylfarnesyl pyrophosphate (GFPP), with formation of multiple products in all cases. The obtained enzyme products included the new macrocycle sestersinellene, the enantiomer of a sesterterpene produced by a terpene synthase from Leucosceptrum canum and the unusual diterpene sinellene ether representing a novel skeleton, reinforcing springtails as an interesting source of terpenes. Extensive isotopic labelling experiments revealed several unusual mechanistic aspects such as the formation of a series of enantiomerically pure products besides one scalemic compound (germacrene D), as well as an unexpected stereochemical course for a reprotonation step in sinellene ether biosynthesis by ScTC2. Taken together, this study lays the foundation for future research on terpene biosynthesis in Collembola, an ancient lineage of arthropods.

Bactrocera umbrosa (Fabricius) is an oligophagous fruit fly of economic importance that infests mainly Artocarpus fruits (Moraceae). The sexual communication system of this species is poorly understood, partly due to difficulties in establishing laboratory colonies. Males of B. umbrosa are strongly attracted to and voraciously fed on methyl eugenol (ME), a naturally occurring plant secondary compound. Here, we elucidate the endogenously produced and ME–derived chemical signals involved in the species’ communication. Gas chromatography–mass spectrometry analyses of pheromonal glands revealed that immature males produced four endogenous compounds, whereas sexually mature males produced six additional volatile compounds, including the terpenoids (R)-6-methyl-2-vinylhept-5-ene-1,2-diol and (S)-7-methyl-3-methyleneoct-6-ene-1,2-diol, which, to our knowledge, have not previously been documented in insects. Following ME ingestion, males accumulated six ME metabolites—eugenol, isoeugenol, (S)-1ʹ-hydroxymethyleugenol ((S)-1ʹ-HME), 2-allyl-4,5-dimethoxyphenol (DMP), (Z)-3,4-dimethoxycinnamyl alcohol (Z-DMC), and (E)-coniferyl alcohol (E-CF). Behavioral assays using a Y-tube olfactometer demonstrated that two endogenous compounds (3-ethyl-2,5-dimethylpyrazine and 6-oxo-1-nonanol) and two ME metabolites (DMP and E-CF) significantly attracted virgin females during courtship. In contrast, none of the endogenous volatiles was attractive to the males, whereas three ME metabolites—eugenol, isoeugenol, and DMP—elicited significant male attraction during dusk. These findings demonstrated that B. umbrosa utilizes endogenous compounds as sex-specific signals to attract conspecific females, while distinct ME-derived metabolites mediate both male-male and male-female communication, facilitating male aggregation and enhancing sexual attraction. These insights contribute to a deeper understanding of the intricate glandular chemistry and chemical communication system of the Artocarpus fruit fly, which may inform future strategies for its control and management.

Linear long-chain hydrocarbons are common constituents of the outer cuticle of most insects. These cuticular hydrocarbons form the first barrier to the environment, preventing desiccation, but also play important roles in communication among many insects, transporting, for example, information on species, sex, or physiological state. Eueides is a genus of heliconiine butterflies, a group known for their complex mimicry systems. We report here the identification and synthesis of large macrocyclic lactones from the cuticles of five Eueides species, which largely replace the hydrocarbons. These lactones have chain lengths of 23-34 and ring sizes of 17-29. They occur in Eueides but not in other closely related genera such as Heliconius, Dryas, Dryadula, Agraulis, or Dione. Each species has a specific mixture of macrocyclic lactones. These unique bouquets may be used in species recognition, as visual cues may be unreliable in mimicry rings. We identified 43 different compounds using GC/MS, GC/IR, and enantioselective synthesis via ring-closing metathesis and Jacobsen hydrolytic kinetic resolution. The absolute configuration could not be determined because these lactones were not separable by gas chromatography on chiral phases.

Recent intensive research on the cypress bark beetle, Phloeosinus aubei was prompted because of its invasion of Central Europe that caused serious damage to scale-leaved conifer ornamental trees. This dynamic also increased the risk of accidental introduction into North America. In contrast to other historically well-studied bark beetles infesting spruce, pine or broad-leaf trees, intense study of the pheromones and host plant kairomones of bark beetles associated with cupressaceous trees has only begun in the past decade. This highly specialized clade is represented by the genus Phloeosinus. The pressing need for semiochemical-baited traps demands the identification of behavior-modifying compounds. This challenge involves unraveling the various stimuli interacting in the complex communication system to reveal the composition of signal bouquets and the absolute configuration of their components capable of evoking behavior responses. In this short overview we describe the recent research results on host-finding and intraspecific chemical communication of P. aubei, with a short outlook on the species of this genus.

Malagasy frogs of the endemic family Mantellinae, among them Gephyromantis granulatus, have a unique feature: femoral glands that secrete volatile semiochemicals used for communication. Here, we report the structure elucidation, total synthesis, and determination of the absolute configuration of the main component of the femoral gland secretion of G. granulatus: granolide C. The structures of two further macrolides, granolides A and B, were also clarified. Structure elucidation was performed using GC/MS, as NMR analysis was not possible due to the limited amount of available material. Various stereoisomers were synthesized using a flexible synthetic approach that enabled access to different substitution patterns found in granolides. Granolides A-C are unique sesquiterpene macrocyclic lactones with ethyl branches instead of the common methyl branches - a feature that is rarely found in nature.

Animals often rely on scent marks to communicate identity across time, yet how chemically dynamic signals remain individually informative is unresolved. Here, we show that domestic cats achieve durable chemical individuality through a reservoir-buffered system based on branched-chain fatty acids (BFAs). Using behavior-guided chemistry, we identify a structurally unusual repertoire of urinary BFAs whose compositional profiles are individually distinctive, stable within individuals, and relatively resistant to post-deposition drift. Cats discriminate donor-derived BFA compositions even when presented on a matched reconstructed urinary lipid background, showing that BFA composition carries discriminable donor-specific information. We trace these compounds to triacylglycerol-rich lipid droplets in the renal cortex, revealing a physiological reservoir that buffers short-term variation and supports repeatable urinary signatures. Comparative analyses across Felidae show that BFA-associated urinary and renal lipid signatures are broadly distributed but non-uniform and diversified in repertoire complexity and storage architecture. These findings identify an organ-level mechanism that stabilizes small-molecule chemical individuality in domestic cats and reveal a diversified reservoir-supported chemical substrate across felid lineages. Video Abstract

Stereochemistry plays a crucial role in pheromone communication among many insects, and pure enantiomers of pheromones are often required to unambiguously evaluate their biological activity. The buckthorn fly, Rhagoletis batava, is attracted to its pheromone (S)-(−)-heptalactone (5-heptanolide), but is potentially deterred, possibly also in a sex-dependent manner, by the (R)-enantiomer. Therefore, larger amounts of highly pure enantiomers of this lactone were needed to clarify their function and attractiveness in the field. We describe here a simple synthesis that enables the preparation of both enantiomers with an enantiomeric excess (ee) greater than 99.5% on a gram scale, investigating several routes. The best and most reliable results were obtained by starting with the racemate resolution of ethyloxirane using Jacobsen’s Co-salen complex, followed by Grignard addition of a 3-butenyl group, ozonolysis, and immediate PCC oxidation. Other procedures, such as enzymatic resolution, were less reliable in our hands and did not achieve such high ee values for both enantiomers.

Three enzymes from African frogs with close sequence homology to avian farnesyl pyrophosphate synthase (FPPS) were studied for their function. All three enzymes converted (2Z,6E)-FPP into several bisabolane sesquiterpenes, with bisabolol and anymol as main products. Experiments with FPPS from Escherichia coli confirmed the same function, suggesting that the observed activity may be of general relevance for FPP synthases. Only one of the frog enzymes showed significant activity in the biosynthesis of FPP from terpene monomers, which may point to an evolutionary process that resulted in a functional switch from an FPPS to a bisabolane synthase. The physiological relevance of these findings is supported by the identification of bisabolol/anymol in gland extracts.

Long‐chain methyl‐branched alkyl methyl ethers are essential constituents of the cuticle of many spiders, regulating water balance and transporting chemical signals used in species recognition. The synthesis of such compounds, or related hydrocarbons found in insects, is usually time‐consuming and not very efficient, mainly due to the long alkyl chains involved. Herein, new strategies for synthesizing such compounds are evaluated. Negishi sp 2 –sp 3 coupling reactions are first investigated and proceed with yields of 50–70%, even with very long alkyl chains. However, such approaches require the synthesis of vinyl iodides, adding additional steps. While the methyl branches are created early in these syntheses, a late introduction strategy proves more favorable. To facilitate this, chain construction is achieved through the addition of an alkynyl anion to aldehydes, resulting in internal propargyl alcohols that serve as substrates for nucleophilic methylation. Iron‐catalyzed methyl Grignard addition yields methylallyl alcohols, which are subsequently converted into the target compounds through hydrogenation and alcohol defunctionalization. Although this approach is successful for compounds with medium chain length, it fails for very long compounds. Instead, allene formation by nucleophilic addition of the methyl group to propargyl mesylates, followed by hydrogenation, gives good yields and clean target ethers.

The need for monitoring the spread of the invasive cypress bark beetle, Phloeosinus aubei , a pest of scale‐leaved conifers across Europe, is urgent. The aggregation pheromone of females was reported earlier; however, an effective trapping method has not yet been developed. Therefore, this study aimed to unravel the males' pheromonal communication system. Volatiles produced by P. aubei males, as well as sex‐ and mating status‐specific extracts from mid‐ and hindguts of unmated and mated males and females were analysed by GC‐EAD, and compounds eliciting antennal responses were identified by GC–MS. Two male‐specific pheromone components, cis ‐verbenol and verbenone, were identified in the extracts from mated males. α‐Pinene, known to be a kairomone component, as well as the female‐produced pheromone (in a combination with (−)‐myrtenol), was also found in extracts of mated males. None of these components were found in unmated males. Four‐arm olfactometer tests showed that females were attracted to the combination of (−)‐myrtenol, (−)‐α‐pinene and (−)‐ cis ‐verbenol, rather than to either (−)‐myrtenol or (−)‐α‐pinene alone. When this ternary blend was combined with (−)‐verbenone, the attractiveness for both males and females was reduced. Female and male P. aubei spent significantly more time in the olfactometer arm containing (−)‐α‐pinene and (−)‐ cis ‐verbenol than in the control arms. The ternary mixture of (−)‐myrtenol, (−)‐α‐pinene and (−)‐ cis ‐verbenol proved to be the most effective trap bait in the field, which could serve as a potent attractant for monitoring of P. aubei .

Domestic cats uniquely accumulate lipid droplets (LDs) in renal proximal tubular epithelial cells, but their chemical composition and biological functions remain unknown. Here, we identify a distinctive renal specialization in felids: lipid droplets enriched in branched-chain fatty acids (BFAs). These BFAs accumulate as triglyceride components and are excreted in urine as free fatty acids with stable and individually distinctive profiles. Behavioral assays show that cats discriminate urine samples based on BFA composition, even against complex volatile backgrounds, suggesting BFAs as robust, metabolically encoded olfactory signatures for individual recognition. Comparative analyses of non-domesticated felids reveal that BFA production is broadly conserved but exhibits both species-specific and individual variation. These findings demonstrate how a core metabolic pathway has been evolutionarily co-opted into a chemical signature system. This discovery highlights an unusual integration of renal physiology with social communication and expand our understanding of lipid metabolism, organ-level adaptation, and the evolution of chemical individuality in mammals. Significance statement Unique lipid droplets in felid kidneys reveal how organ-specific metabolism can be adapted for social communication. ### Competing Interest Statement The authors have declared no competing interest. Japan Society for the Promotion of Science, https://ror.org/00hhkn466, 25K22460, 25KJ0526

The structure determination and occurrence of curvisetone (1), a tricyclic nor-diterpenoid from the tiny Collembola Sinella curviseta, is reported. Utilizing NMR analysis and mass spectrometry, we identified curvisetone's unique carbon skeleton and its occurrence in various sex and life stages. Curvisetone, carrying an unprecedented carbon tricyclic ring system, is an example of the distinct terpene usage of Collembola, which differentiates them from other arthropods.

Covering up to September 2024Collembola, commonly known as springtails, are abundant and important members of soil ecosystems. Due to their small size and hidden life, not much is known about their secondary metabolites. This chemistry is remarkably different from that of insects, with which they share a common ancestor, although they diverged already around 450 mya. Here we describe what is known so far, mainly compounds for chemical defence and cuticular lipids, as well as chemical signals. The uniqueness of the structures found is striking, many of which are not known from other natural sources. These include polychlorinated benzopyranones, small alkaloids, hetero-substituted aromatic compounds, and a diverse terpene chemistry, including highly branched compounds.

Antiaphrodisiacs are chemical bouquets physically delivered from male to female individuals upon copulation which discourage further mating and reduce sperm competition by rendering the female less attractive. Since antiaphrodisiacs may not offer an honest signal of female receptivity, in polyandrous species they may undergo faster diversification resulting from sexual conflict. The Heliconiini tribe of butterflies includes a polyandrous (free-mating) and a monandrous (pupal-mating) clade, both known to produce diverse antiaphrodisiac mixtures as part of their abdominal blends. Using multivariate phylogenetic comparative methods, we analyzed the genital blends of 36 Heliconiini species to test the hypothesis that blend diversity results from male-male competition in polyandry. We found no evidence for shifts in blend diversification rate corresponding to changes in mating strategy, implying male-male competition may have a weaker effect on pheromone diversification in this group than previously thought. The genital blends of most species are dominated by one of four highly volatile compounds; (E)-β-ocimene, octen-3-one, sulcatone and 4-hydroxycyclopent-2-en-1-one. Based on the function of (E)-β-ocimene as the behaviourally active antiaphrodisiac in H. melpomene, we propose a similar role in other species for the other volatiles. We test this hypothesis by investigating 4-hydroxycyclopent-2-en-1-one occurrence in Heliconius sara. While we detect no sex-based differences on its presence, we find the compound is undetectable when larvae are not fed their preferred host plant, providing an intriguing potential link between host plant and reproductive cues. This in turn shows that captive-bred samples do not always provide realistic results and this awareness is important for future experiments.

Methylated long-chain aliphatic compounds such as terminal methyl ethers are a common compound type found on the epicuticular layer of arthropods, e.g., spiders. Because complex mixtures are encountered in small amounts when analyzing these mixtures, GC/MS is the method of choice for characterizing the individual constituents. However, the methyl branch location cannot be deduced from the original spectra due to the easy loss of methanol, resulting in nonspecific spectra, and a complex derivatization scheme has been employed to address this issue. We noted that although mass spectra obtained by EI-quadrupol and EI-Orbitrap ionization are superficially quite similar, a +2.0 V C-trap offset of the latter leads to reduced fragmentation. The high-resolution Orbitrap spectra contain enough information to allow for methyl group localization in the chain. However, the spectra of the methyl ethers contain many ions, making individual analysis quite time-consuming. Therefore, scripts using Excel and R were developed with the help of ChatGPT 4.0, resulting in ion series spectra (ISS) that contained only ions of a specific ion series. The analysis of 11 synthetic methyl ethers showed that especially the ion series CnH2n+1O (ISS45) and CnH2n-2 (ISS40) are of high diagnostic value, together with some methoxy group-induced fragmentation. The approach was successfully tested with lipids from the spider Tetragnatha versicolor, which had been previously analyzed by derivatization, and with web extracts of Erigone atra, revealing 1-methoxy-2,16-dimethylhenicosane as a male-specific component─the first spider methyl ether in a volatility range that would allow detection via the gas phase. This approach can also be applied to structurally related primary alcohols, although the diagnostic ions are of lower intensity.

Reconstruction of long-segment peripheral nerve gaps remains a clinical challenge, as neither autografts nor FDA-approved nerve conduits achieve satisfactory functional recovery. Conduits filled with native Trichonephila dragline silk show promise for nerve defects exceeding the critical length, but translating natural silk to clinical use has limitations, necessitating research into recombinant silk replica. The search for optimal silk templates is ongoing, with numerous spider species still unexplored. This study aims to compare the ability of four native silk fibers from phylogenetically diverse spider families to support nerve regeneration. The influence of fiber morphology, primary and secondary protein structures, surface charge, chemical composition, and mechanical properties on the initial cell attachment is studied. Results demonstrate that silk collected from Peucetia lucasi do not adequately support Schwann cell adhesion, which is caused by the lack of a lipid layer and the limited fiber wettability. This reduced wettability, governed by the ratio of hydrophilic and hydrophobic amino acids of silk, is particularly relevant when considering the deployment of uncoated artificial silk fibers for neural tissue engineering. This knowledge is crucial for paving the way toward full functional recovery after peripheral nerve injury via implanting advanced synthetic nerve guidance conduits enhanced with luminal silk alternatives.

The sense of smell is a central sensory modality of most terrestrial species. However, our knowledge of olfaction is based on vertebrates and insects. In contrast, little is known about the chemosensory world of spiders and nothing about how they perform olfaction despite their important ecological role. The orb-weaving spider Argiope bruennichi lends itself to an in-depth study on olfaction as it is one of the few spider species whose volatile sex pheromone, emitted by females to attract males, is known. We combined ultrastructural and electrophysiological analyses and found that previously overlooked sensilla with wall pores are abundant on all walking legs of A. bruennichi males. We compared the ultrastructure of these wall-pore sensilla with those known to perform olfaction in insects, exploring similarities and differences. Electrophysiological single sensillum recordings demonstrated that the wall-pore sensilla in A. bruennichi respond highly sensitive and in a concentration-dependent manner to the sex pheromone. Our study demonstrates male-specific sensilla for detecting signaling females, whereas females and subadult males are devoid of wall pore sensilla. In a preliminary comparative morphological analysis using 19 species from 16 spider families, we found that wall-pore sensilla occur in male spiders from most, but not in basally branching clades or in Salticids, suggesting that wall-pore sensilla evolved at least once within spiders and were lost at least once. This research significantly expands our knowledge of the sensory ecology of spiders, will stimulate studies on the diversity and function of sensilla, as well as studies on the evolution of olfaction in arthropods.

A short, gram-scale synthesis of 2-hydroxy-6-nona-1,3-dienylbenzaldehyde (HNDB, albiducin B) starting from 3-hydroxyphthalic anhydride is reported that also allows access to the fungal metabolite calidiol A. HNDB is needed to understand the ecology of certain euglossine bees that actively search for this compound for uptake. The original source of HNDB is unknown.

A central question in evolutionary biology is what drives the diversification of lineages. Rapid, recent radiations are ideal systems for this question because they still show key morphological and ecological adaptations associated with speciation. While most research on recent radiations focuses on those occurring in insular environments, less attention has been given to continental radiations with complex species interactions. Here, we study the drivers of continental radiations of Melinaea and Mechanitis butterflies (Nymphalidae: Ithomiini), which have rapidly radiated in the continental Neotropics. They are classical models for Amazonian biogeography and color pattern mimicry and have been proposed as biodiversity indicators. We generated reference genomes for five species of each genus and whole-genome resequencing data of most species and subspecies covering a wide geographic range to assess phylogeographic relationships, hybridization patterns, and chromosomal rearrangements. Our data help resolve the classification of these taxonomically challenging butterflies and reveal very high diversification rates. We find rampant evidence of historical hybridization and putative hybrid species in both radiations, which may have facilitated their rapid diversification by enriching the genetic diversity. Moreover, we identified dozens of chromosomal fusions and fissions between congeneric species that have likely expedited reproductive isolation. We conclude that interactions between geography, hybridization and chromosomal rearrangements have contributed to these rapid radiations in the highly diverse Neotropical region. We hypothesize that rapid radiations may be spurred if repeated periods of geographic isolation are combined with lineage-specific rapid accumulation of incompatibilities, followed by secondary contact with some gene exchange.