Wax on, wax off: nest soil facilitates indirect transfer of recognition cues between ant nestmates

Social animals use recognition cues to discriminate between group members and non-members. These recognition cues may be conceptualized as a label, which is compared to a neural representation of acceptable cue combinations termed the template. In ants and other social insects, the label consists of a waxy layer of colony-specific hydrocarbons on the body surface. Genetic and environmental differences between colony members may confound recognition and social cohesion, so many species perform behaviors that homogenize the odor label, such as mouth-to-mouth feeding and allogrooming. Here, we test for another mechanism of cue exchange: indirect transfer of cuticular hydrocarbons via the nest material. Using a combination of chemical analysis and behavioral experiments with Camponotus aethiops ants, we show that nest soil indirectly transfers hydrocarbons between ants and affects recognition behavior. We also found evidence that olfactory cues on the nest soil influence nestmate recognition, but this effect was not observed in all colonies. These results demonstrate that cuticular hydrocarbons deposited on the nest soil are important in creating uniformity in the odor label and may also contribute to the template

Evolution of sociality in spiders leads to depleted genomic diversity at both population and species level

textcopyright 2017 John Wiley Sons Ltd.Across several animal taxa, the evolution of sociality involves a suite of characteristics, a "social syndrome," that includes cooperative breeding, reproductive skew, primary female-biased sex ratio, and the transition from outcrossing to inbreeding mating system, factors that are expected to reduce effective population size (Ne). This social syndrome may be favoured by short-term benefits but come with long-term costs, because the reduction in Ne amplifies loss of genetic diversity by genetic drift, ultimately restricting the potential of populations to respond to environmental change. To investigate the consequences of this social life form on genetic diversity, we used a comparative RAD-sequencing approach to estimate genomewide diversity in spider species that differ in level of sociality, reproductive skew and mating system. We analysed multiple populations of three independent sister-species pairs of social inbreeding and subsocial outcrossing Stegodyphus spiders, and a subsocial outgroup. Heterozygosity and within-population diversity were sixfold to 10-fold lower in social compared to subsocial species, and demographic modelling revealed a tenfold reduction in Ne of social populations. Species-wide genetic diversity depends on population divergence and the viability of genetic lineages. Population genomic patterns were consistent with high lineage turnover, which homogenizes the genetic structure that builds up between inbreeding populations, ultimately depleting genetic diversity at the species level. Indeed, species-wide genetic diversity of social species was 5-8 times lower than that of subsocial species. The repeated evolution of species with this social syndrome is associated with severe loss of genomewide diversity, likely to limit their evolutionary potential

Two hymenopteran egg sac associates of the tent-web orbweaving spider, Cyrtophora citricola (Forskål, 1775) (Araneae, Araneidae)

We report the discovery of two wasp species emerging from egg sacs of the spider Cyrtophora citricola (Forskål 1775) collected from mainland Spain and the Canary Islands. We identify one as Philolema palanichamyi (Narendran 1984) (Hymenoptera, Eurytomidae) and the other as a member of the Pediobius pyrgo (Walker 1839) species group (Hymenoptera, Eulophidae). This is the first report of Philolema in Europe, and the first documentation of hymenopteran egg predators of C. citricola. The latter finding is particularly relevant, given the multiple invasive populations of C. citricola in the Americas and the Caribbean, where neither egg sac predation nor parasitism is known to occur. We describe rates of emergence by Ph. palanichamyi from spider egg sacs collected from the southern coast of Spain and estimate sex ratios and body size variation among males and females. We also re-describe Ph. palanichamyi based on the female holotype and male paratype specimens

Animal behaviour: task differentiation by personality in spider groups

Dispatch: In social animals, group efficiency is often assumed to increase with task differentiation, but this requires that individuals are better than generalists at the task they specialize in. A new study finds that individual Anelosimus studiosus spiders do predominantly perform the task they excel at, in line with their individual personality type, when they are placed in groups

Food intake and reproduction data

Main data file: food intake and reproduction data at the level of individual spider

Colony level data

Data at the level of individual spider colonies, e.g. colony size

Additional data

Data at the level of field sites (e.g. spider density, average colony sizes, and food abundance) + Ambient temperature data + Data for correlating web sizes and spider body size

Insect measurements

Data from trapping of insects to estimate food abundanc

Validation of food intake

Data from second field experiment for validating food intake values (10 observations per day rather than 4 observations per day; estimation of prey sizes caught and biomass ingested

Market Manipulation video data

Video data (food returns, foraging time and aggression) before and after treatment in the Market Manipulation experimen