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The hydrophobic layer of the arthropod cuticle acts to maintain water balance, but can also serve to transmit chemical signals via cuticular hydrocarbons (CHC), essential mediators of arthropod behavior. CHC signatures typically vary qualitatively among species, but also quantitatively among populations within a species, and have been used as taxonomic tools to differentiate species or populations in a variety of taxa. Most work in this area to date has focused on insects, with little known for other arthropod groups such as ticks. The worldwide distribution and extensive host-range of the seabird tick Ixodes uriae make it a good model to study the factors influencing CHC composition. Genetically differentiated host-races of I. uriae have evolved across the distribution of this species but the factors promoting sympatric population divergence are still unknown. To test for a potential role of host-associated CHC in population isolation, we collected I. uriae specimens from two of its seabird hosts, the Atlantic puffin (Fratercula arctica) and the common guillemot (Uria aalge) in different colonies in Iceland. Using gas-chromatography and mass-spectrometry, we detected a complex cuticular mixture of 22 hydrocarbons, including n-alkanes, methyl-alkanes and alkenes ranging from 17 to 33 carbons in length. We found that each population had a distinct CHC profile. The host group explained the greatest amount of population divergence, with long-chain hydrocarbons being more abundant in puffin tick populations compared to guillemot tick populations. Future work will now be required to test whether the different CHC signals reinforce assortative mating, thereby playing a role in generating I. uriae population divergence patterns, and to evaluate diverse hypotheses on the origin of distinct population signatures.

For organisms in temperate environments, seasonal variation in resource availability and weather conditions exert fluctuating selection pressures on survival and fitness, resulting in diverse adaptive responses. By manipulating resource availability on a local spatial scale, we studied seasonal patterns of resource use within natural populations of burying beetles Nicrophorus vespilloides in a Norfolk woodland. Burying beetles are necrophagous insects that breed on vertebrate carcasses. They are active in Europe between April and October, after which they burrow into the soil and overwinter. Using breeding and chemical analyses, we compared the fecundity and physiological state of beetles that differed in their seasonal resource use. We found seasonal variation in carrion use by wild burying beetles and correlated differences in their reproductive success and cuticular hydrocarbon profiles. Our results provide novel insight into the seasonal correlates of behaviour, physiology and life history in burying beetles. [ABSTRACT FROM AUTHOR]

Ant evolutionary success depends mainly on the coordination of colony members, who recognize nestmates based on the cuticular hydrocarbon (CHC) profile of their epicuticle. While several studies have examined variations in this crucial factor for colony identity, few have investigated the anthropic impact on CHC profiles, and none have focused on Lasius paralienus. Here, we surveyed the changes in L. paralienus CHC assemblages across agroecosystems and assessed whether different vineyard management influences these profiles. Soil sampling within ant nests and in close surroundings was performed to measure microhabitat variations. Our results show that the cuticular chemical composition of Lasius paralienus is mainly affected by the differences between areas, with an existing but unclear anthropic influence on them. Normalized soil respiration partially explains these interarea variations. Irrespective of the conventional or organic management, human activities in agroecosystems mostly impacted L. paralienus linear alkanes, a specific class of CHCs known to play a major role against dehydration, but also affected the abundance of compounds that can be pivotal for maintaining the colony identity. Our findings suggest that vineyard practices primarily affect features of the ant cuticle, potentially enhancing microclimate adaptations. Still, the potential effects as disruptive factors need further investigation through the implementation of behavioral bioassays. [ABSTRACT FROM AUTHOR]

Mice can obtain information about a new food source through olfactory cues of conspecifics and consequently develop an attraction for this diet. The social transmission of food preference (STFP) takes place directly, during an encounter with a conspecific or indirectly, via feces. In indirect STFP, the digestive process can degrade odorant compounds characterizing the food, impairing the matching between feces and food. In a previous study, indirect STFP was efficient when the information support was a composite odorant. We, thus, hypothesized that the acquisition of indirect STFP depends on the multiplicity of the odorant compounds present in diets. Tested in female house mice (Mus musculus domesticus) our results showed that a single odorant compound as information support was not sufficient to induce an indirect STFP. Chemical analysis did not reveal the presence of the compounds in feces suggesting that the degradation of diet cues during the digestive process prevented the pairing between feces and food. By using a process that limits the degradation of molecules, we performed indirect STFP when the pertinent information was represented by a single odorant compound and multiple odorant compounds. Unlike with multiple odorant compounds, our results did not show a clear indirect STFP with single odorant compound, despite their presence in feces confirmed by chemical analysis. We conclude that constraints associated to indirect STFP can be removed by the multiplicity of information characterizing the diet both by reducing the degradation risk during the digestive process and by allowing an accurate assessment of diet consumed by the conspecific. [ABSTRACT FROM AUTHOR]

Social insects are well known for their extremely rich chemical communication, yet their sex pheromones remain poorly studied. In the thermophilic and thelytokous ant, Cataglyphis cursor, we analyzed the cuticular hydrocarbon profiles and Dufour’s gland contents of queens of different age and reproductive status (sexually immature gynes, sexually mature gynes, mated and egg-laying queens) and of workers. Random forest classification analyses showed that the four groups of individuals were well separated for both chemical sources, except mature gynes that clustered with queens for cuticular hydrocarbons and with immature gynes for Dufour’s gland secretions. Analyses carried out with two groups of females only allowed identification of candidate chemicals for queen signal and for sexual attractant. In particular, gynes produced more undecane in the Dufour’s gland. This chemical is both the sex pheromone and the alarm pheromone of the ant Formica lugubris. It may therefore act as sex pheromone in C. cursor, and/or be involved in the restoration of monogyny that occurs rapidly following colony fission. Indeed, new colonies often start with several gynes and all but one are rapidly culled by workers, and this process likely involves chemical signals between gynes and workers. These findings open novel opportunities for experimental studies of inclusive mate choice and queen choice in C. cursor. [ABSTRACT FROM AUTHOR]

Background: The number of cases of Chlamydia trachomatis (Ct) diagnosed has increased in the past 15 years in France as well as in other European countries. This paper reports a randomised controlled trial (RCT) to evaluate whether the offer of home-based testing over the internet increased the number of young people tested for chlamydia compared with the current testing strategy and to estimate the number and risks factors of the infected population. This RCT took place as an element of the Chlamyweb Study-a study aiming to evaluate an intervention (the Chlamyweb Intervention) involving the offer of a free self-sampling kit online to sexually active men and women aged 18-24 years in France.Methods: Participants in the Chlamyweb RCT (n=11 075) received either an offer of a free self-sampling kit (intervention group) or were invited to be screened in primary care settings (control group). Risks ratios were used to compare screening rates between the intervention and control groups. Risk factors were analysed for infected people in the intervention group.Results: The screening frequency was about three times higher among young people who received a self-sampling kit than those who only received a tailored recommendation to be screened (29.2% vs 8.7%). Although rates of screening among men were lower than among women (23.9% vs 33.9%), the intervention effect was greater among men (adjusted risk ratios (aRR)=4.55 vs aRR=2.94). Ct positivity (6.8%) was similar to that observed in STI clinics. It was higher in women (8.3%) than in men (4.4%).Conclusions: These results invite us to consider the establishment of a large home-based screening programme, although additional studies including economic assessments are needed to evaluate the most appropriate combination of strategies in the French context.Trial Registraion Number: AFFSAPS n° IDRCB 0211-A01000-41; Results. [ABSTRACT FROM AUTHOR]

1. The ecological success of social insects lies in their ability to prevent the exploitation of colony resources by competitors or parasites. Nestmate recognition is therefore of crucial importance in maintaining the integrity of the colony. Furthermore, inter-colony competitive relationships are often complex, as many species discriminate between neighbours and strangers, with reduced (the dear enemy phenomenon) or increased levels of aggression towards nearby colonies, depending on the species. In this context, between-species comparisons could be particularly helpful to investigate the proximate causes underlying this context-dependent phenomenon, but these are notoriously lacking. 2. Here an attempt was made to circumvent this drawback by studying three closely related sympatric ant species with very similar life histories that belong to the Neoponera apicalis complex. The present study investigated how nestmate recognition and inter-colony competitive relationships were influenced by spatial, chemical and genetic distances between colonies. 3. It was found that one species, N. apicalis morph 7, showed a clear dear enemy phenomenon with no influence of chemical and genetic distances, suggesting the existence of a learning process. In contrast, N. apicalis morph 4 and Neoponera verenae morph 1 failed to show any strong discrimination between close and distant non-nestmates. 4. These results are discussed in the light of the observed interspecific variation in nesting preferences, possibly constraining the opportunities of familiarisation between nearby nests, and modulating the competition for resources between colonies. 5. It is argued that this study further reinforces the relative threat level hypothesis as an ultimate explanation for neighbour-stranger discrimination processes. [ABSTRACT FROM AUTHOR]

Background: The number of cases of Chlamydia trachomatis (Ct) diagnosed has increased in the past 15 years in France as well as in other European countries. This paper reports a randomised controlled trial (RCT) to evaluate whether the offer of home-based testing over the internet increased the number of young people tested for chlamydia compared with the current testing strategy and to estimate the number and risks factors of the infected population. This RCT took place as an element of the Chlamyweb Study-a study aiming to evaluate an intervention (the Chlamyweb Intervention) involving the offer of a free self-sampling kit online to sexually active men and women aged 18-24 years in France., Methods: Participants in the Chlamyweb RCT (n=11 075) received either an offer of a free self-sampling kit (intervention group) or were invited to be screened in primary care settings (control group). Risks ratios were used to compare screening rates between the intervention and control groups. Risk factors were analysed for infected people in the intervention group., Results: The screening frequency was about three times higher among young people who received a self-sampling kit than those who only received a tailored recommendation to be screened (29.2% vs 8.7%). Although rates of screening among men were lower than among women (23.9% vs 33.9%), the intervention effect was greater among men (adjusted risk ratios (aRR)=4.55 vs aRR=2.94). Ct positivity (6.8%) was similar to that observed in STI clinics. It was higher in women (8.3%) than in men (4.4%)., Conclusions: These results invite us to consider the establishment of a large home-based screening programme, although additional studies including economic assessments are needed to evaluate the most appropriate combination of strategies in the French context., Trial Registraion Number: AFFSAPS n° IDRCB 0211-A01000-41; Results., Competing Interests: Competing interests: None declared., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.)