Common Practice Solvent Extraction Does not Reflect Actual Emission of a Sex Pheromone During Butterfly Courtship

Olfactory communication can be of critical importance for mate choice decisions. Lepidoptera are key model systems for understanding olfactory communication, particularly considering sex pheromone signaling in the context of sexual selection. Solvent extraction or rinsing of pheromone-producing structures is a widespread method for quantifying sex pheromones, but such measures reflect what is stored and may not represent what is actually emitted by an individual during courtship. Here, we address this point for the first time by quantifying the components of the male sex pheromone (MSP) of interacting Bicyclus anynana butterflies, a species for which much information is available onthe role played by MSPs in affecting mating success. Using headspace sampling during courtship and solvent extraction after completion of experiments using the same males, we were able to track individual traits. Our results show that solvent extracts do not reflect quantities of MSP components emitted by live butterflies. We further show that MSP amounts obtained using headspace sampling correlated with male mating success, but solvent extracts did not. Our results further strongly suggest that males actively control MSP emission when faced with increased male-male competition. Common practice solvent extracts may thus not serve as an adequate proxy for male sex pheromone signaling as they are perceived by choosy females. Our study serves as a proof of principle that quantification of male sex pheromone components depends on the method of collection, which could apply to many other insects using short-range chemical signals. This affects our understanding of how sexual selection shapes the evolution of sexually-selected chemical traits

The aggregation pheromone of the Western flower thrips

The western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) is a polyphagous insect pest and virus vector with a ubiquitous distribution. Its control necessitates an IPM strategy and as part of this there is a potential for exploiting the male-produced aggregation pheromone. Neryl (S)-2-methylbutanoate and (R)-lavandulyl acetate have previously been identified as male-produced compounds with the former being shown to increase trap catch in glasshouse trials. Experiments that varied the visual stimulus oi the luie indicated that a visual stimulus was needed for the lure to work.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Data from: Young male mating success is associated with sperm number but not with male sex pheromone titres

Background: Intraspecific communication is of crucial importance throughout the animal kingdom and may involve a combination of visual, gustatory, olfactory and acoustic cues. Variation in male sex pheromone amount and composition may convey important information to female conspecifics, for instance on species identity or age. However, whether increased male pheromone titres are associated with fitness benefits for the female, thus indicating a role as an honest signal, is under debate. Results: Against this background, we tested in the butterfly Bicyclus anynana (1) whether young males being successful or unsuccessful in gaining a mating differed in sex pheromone titres and (2) for associations between male pheromone titres and spermatophore mass, eupyrene sperm number, and a variety of female and offspring life-history traits. Successful and unsuccessful males did not differ in pheromone titres, however eupyrene sperm number was much higher in successful males. Pheromone titres were not associated with any fitness-related female or offspring trait measured in our study, though correlation analyses yielded evidence for trade-offs among specific traits. Patterns did not differ among control and olfaction-blocked females. Conclusion: Therefore, we suggest that in young B. anynana pheromone titres do not indicate male quality

MSP data analysis

The package contains the raw data/excel files for the two experiments, which were conducted in the underlying publication

Chemical composition of anal droplets of the eusocial gall-inducing thrips Kladothrips intermedius

The eusocial Acacia gall-inducing thrips Kladothrips intermedius (Thysanoptera: Phlaeothripinae) secretes defensive anal droplets when threatened. In addition to harmful substances, droplets of other thysanopteran species are known to contain semiochemicals such as alarm pheromones and/or repellents against enemies. Both Kl. intermedius larval stages and adult castes (soldiers and dispersers) produce anal droplets. In addition, a recent study has shown that soldier droplets may contain an alarm pheromone. Using multiple sampling methods (extraction in solvent, solid phase microextraction and direct injection), we analyzed the content of adults and second instar larvae anal droplets by gas chromatography coupled to mass spectrometry. Anal droplets comprised of a set of saturated and monounsaturated short-chain fatty acids, including three compounds with a terminal double bond (7-octenoic acid, 8-nonenoic acid and 9-decenoic acid). The latter are here reported for the first time in an insect species. In addition, putative unsaturated wax esters similar to those found in the secretion of other social insects were also detected in droplets. In order to investigate the physiological activity of the acids, single sensillum recordings were performed on adult Kl. intermedius as well as on adults of its kleptoparasite, Koptothrips dyskritus, targeting olfactory receptor neurons in the antennal sensilla basiconica. While olfactory perception of the acids in these species cannot be completely excluded, our analyses indicate that sensilla basiconica are not strongly sensitive to these droplet compounds