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Overwintering insects are facing energetic challenges because of food shortage, low temperature, and desiccation stress. Paper wasps of the genus Polistes overwinter as mated adults (gynes) in hibernacula protecting them from predation, snow, and rain but barely from low environmental temperature. In different climates, they face differing overwintering temperature regimes, and therefore they may differ in their energy use. We investigated how much of energy resources built up until autumn is used during diapause dormancy in natural hibernacula by measuring lipid, glycogen, and free carbohydrate content in autumn and early spring in Polistes dominula from temperate European (Austrian) and warm Mediterranean (Italian) climate and Polistes gallicus from Mediterranean climate. Winter energy consumption amounted to ~ 339 and ~ 310 J per wasp in the Austrian and Italian Polistes dominula populations. The smaller Italian Polistes gallicus consumed ~ 247 J. This amounts to 2.62, 2.35, and 1.79 J per day. Of this, the energy demand was mainly fuelled by lipids (84%, 93%, and 90%, respectively), but glycogen stores contributed also considerably (16%, 6%, and 9%). Free carbohydrates decreased only by 0.7%, 1%, and 0.8%. While fat stores seem still sufficient in spring, the wasps depleted most of their carbohydrates. The energy reserves of 396, 400, and 147 J per wasp remaining in spring in the three populations seem sufficient to fuel rest or simple brood care activities for a whole summer but restrict foraging flights to a few hours (~ 3.5–6 h). Results suggest that energy supply might become challenging in expected future climate scenarios. [ABSTRACT FROM AUTHOR]

Mitochondrial (mtDNA) genes have served as widely utilised genetic loci for phylogenetic and phylogeographic studies of animals. However, the phylogenetic performance of many mtDNA genes has not been empirically evaluated across lineages within hymenopteran wasps. To address this question, we assembled and analysed mitogenomic data from social wasps, representing the four recognised tribes of Polistinae and all Epiponini genera. Additionally, we evaluated whether mtDNA gene order in Polistinae is congruent with its tribal classification. Using concatenation phylogenetic methods, we show phylogenetic congruence between mitogenomic and nuclear data. Statistically comparing the phylogenetic performance of individual mtDNA genes, we demonstrate that for social wasps the molecular markers COI, 16S, NAD5, and NAD2 perform best, while ATP6, COII, and 12S show the worst results. Finally, we verified that the tRNA cluster close to the noncoding region is a hotspot of genetic rearrangements in Vespidae and can be used as additional information for the systematics of this group. Together, these results indicate that mitogenomes contain robust phylogenetic signal to elucidate the evolutionary history of Vespidae. Moreover, our study identifies the best choice of mtDNA markers for systematic investigations of social wasps. [ABSTRACT FROM AUTHOR]

The Neotropical realm harbours unparalleled species richness and hence has challenged biologists to explain the cause of its high biotic diversity. Empirical studies to shed light on the processes underlying biological diversification in the Neotropics are focused mainly on vertebrates and plants, with little attention to the hyperdiverse insect fauna. Here, we use phylogenomic data from ultraconserved element (UCE) loci to reconstruct for the first time the evolutionary history of Neotropical swarm-founding social wasps (Hymenoptera, Vespidae, Epiponini). Using maximum likelihood, Bayesian, and species tree approaches we recovered a highly resolved phylogeny for epiponine wasps. Additionally, we estimated divergence dates, diversification rates, and the biogeographic history for these insects in order to test whether the group followed a 'museum' (speciation events occurred gradually over many millions of years) or 'cradle' (lineages evolved rapidly over a short time period) model of diversification. The origin of many genera and all sampled extant Epiponini species occurred during the Miocene and Plio-Pleistocene. Moreover, we detected no major shifts in the estimated diversification rate during the evolutionary history of Epiponini, suggesting a relatively gradual accumulation of lineages with low extinction rates. Several lines of evidence suggest that the Amazonian region played a major role in the evolution of Epiponini wasps. This spatio-temporal diversification pattern, most likely concurrent with climatic and landscape changes in the Neotropics during the Miocene and Pliocene, establishes the Amazonian region as the major source of Neotropical swarm-founding social wasp diversity. [ABSTRACT FROM AUTHOR]

Evolutionary transitions in social behavior are often associated with changes in species' brain architecture. A recent comparative analysis showed that the structure of brains of wasps in the family Vespidae differed between solitary and social species: the mushroom bodies, a major integrative brain region, were larger relative to brain size in the solitary species. However, the earlier study did not account for body size effects, and species' relative mushroom body size increases with body size in social Vespidae. Here we extend the previous analysis by measuring the effects of body size variation on brain structure differences between social and solitary vespid wasps. We asked whether total brain volume was greater relative to body size in the solitary species, and whether relative mushroom body size was greater in solitary species, after accounting for body size effects. Both total brain volume and relative mushroom body volume were significantly greater in the solitary species after accounting for body size differences. Therefore, body size allometry did not explain the solitary versus social species differences in brain structure. The evolutionary transition from solitary to social behavior in Vespidae was accompanied by decreases in total brain size and in relative mushroom body size. [ABSTRACT FROM AUTHOR]

Biocontrol agents can help reduce pest populations as part of an integrated pest management scheme, with minimal environmental consequences. However, biocontrol agents are often non-native species and require significant infrastructure; overuse of single agents results in pest resistance. Native biocontrol agents are urgently required for more sustainable multi-faceted approaches to pest management. Social wasps are natural predators of lepidopteran pests, yet their viability as native biocontrol agents is largely unknown. Here, we provide evidence that the social paper wasp Polistes satan is a successful predator on the larvae of two economically important and resilient crop pests, the sugarcane borer Diatraea saccharalis (on sugarcane Saccharum spp.) and the fall armyworm Spodoptera frugiperda (on maize Zea mays); P. satan wasps significantly reduce crop pest damage. These results provide the much-needed baseline experimental evidence that social wasps have untapped potential as native biocontrol agents for sustainable crop production and food security. [ABSTRACT FROM AUTHOR]

Social insects depend on their nests for protection against predation and abiotic threats. Accordingly, the chemical compounds present in the material wasps use to build their nests can both facilitate communication and repel predators. It is herein hypothesized that different wasp species build their nests with different structure and substrate materials and that such materials consist of chemical compounds related to unique wasp behavior and outside temperature variation. To test this hypothesis, nests were collected from three species of social wasps, the samples of which were subjected to temperature variation under laboratory conditions. The compounds present in the substrate were analyzed by gas chromatography coupled to mass spectrometry. Chemical compounds identified in the nest material of the three species responded differently to temperature variation. Chemical compounds from Polybia nests were altered significantly when subjected to temperature variation, whereas the nests of Polistes versicolor did not significantly change in relation to the control. The differences found between Polistes and Polybia nests may be related to genetic factors, but also to the type of nest they construct. It is possible that divergent evolutionary strategies for maintaining colony temperature, as a function of the chemical composition of the nests, may have appeared between wasps that have open and closed nests. In relatively small colonies, nest substrate is more resistant to temperature variation because it is composed of a greater diversity of elements and thus capable of holding heavier, longer carbon chains. Our results suggest that chemical compounds in the nest material of the three wasp species analysed responded differently to fluctuating ambient temperatures and that such variation could result from the biochemical differences of unique wasp species or from thermoregulation strategies of colonies. • Compounds in the nest material maintaining thermostability against ambient elements. • Different answer of the compounds of the nest of species to temperature variation. • Wasp with open and closed combs have divergent strategie for keep colony temperature. • The composition of enveloped nest is more susceptible to temperature than open nest. • Polistes versicolor do possess a greater number of compounds. [ABSTRACT FROM AUTHOR]

Recent studies have reported incipient morphological caste dimorphism in the Van der Vecht organ size of some temperate Polistes paper wasps. Whether species other than the temperate ones show a similar pattern remains elusive. Here, we have studied some Neotropical Polistes species. By comparing females collected through the year, we showed caste related differences in the size of the Van der Vecht organ in P. ferreri (body size corrected Van der Vech organ size of queens = 0.45 ± 0.06, workers = 0.38 ± 0.07 mm2, p = 0.0021), P. versicolor (body size corrected Van der Vech organ size of queens = 0.54 ± 0.11, workers = 0.46 ± 0.09 mm2, p = 0.010), but not P. simillimus (body size corrected Van der Vech organ size of queens = 0.52 ± 0.05, workers = 0.49 ± 0.06 mm2, p = 0.238). Therefore, it seems that queens and workers of some Neotropical Polistes have diverged in their ontogenic trajectory of the Van der Vecht organ size, providing clear evidence for incipient morphological caste dimorphism. As Polistes are distributed mostly in the tropics, we propose that physical caste differences may be widespread in the genus. Also, we highlight that morphological divergence in the queen–worker phenotypes may have started through differential selection of body structures, like the Van der Vecht organ. [ABSTRACT FROM AUTHOR]

The social wasp genus R opalidia includes both 'swarm-founding' species with large, multi-queen colonies, and 'independent-founding' species that have smaller colonies and fewer queens. Swarm-founding evolved from independent-founding, and a key element of this transition was the evolution of queen cycling, which elevates relatedness despite high average queen numbers. Queen cycling is a form of split-sex ratios; colonies with few queens specialise on new queen production, while colonies with many queens specialise on male production. This is consistent with worker preferences resulting from relatedness asymmetry ( RA) to male and female brood but can also result from other factors. We characterised the demographic and genetic structure of colonies from three species of independent-founding R opalidia ( R . excavata, R . revolutionalis and R . g regaria) to better understand the evolutionary origins of split-sex ratios and queen cycling in their swarm-founding relatives. We found that colonies of all three species varied in genetic structure, driving variation in RA. In colonies where the workers' RA was high (i.e. workers were more related to female than male brood), the proportion of males in the brood was lower, consistent with the relatedness-based preferences of the workers. We also found that the proportion of males decreased in colonies with more mated and reproductively developed females. Our model explained 23% of the deviance in sex ratio across all three species and suggests that the workers manipulate the sex ratio in response to RA but that other factors are clearly important also. These results further suggest that split-sex ratios and queen cycling in the swarm-founding wasps are rooted in worker control of the colony sex ratio, and that such worker control may have occurred in their independent-founding ancestors, enabling the subsequent evolution of large, multi-queen societies. [ABSTRACT FROM AUTHOR]

Circadian rhythms in social insects are highly plastic and are modulated by multiple factors. In addition, complex behaviors such as sun-compass orientation and time learning are clearly regulated by the circadian system in these organisms. Despite these unique features of social insect clocks, the mechanisms as well as the functional and evolutionary relevance of these traits remain largely unknown. Here we show a modification of the Drosophila activity monitoring (DAM) system that allowed us to measure locomotor rhythms of the honey bee, Apis mellifera (three variants; gAHB, carnica and caucasica), and two paper wasps (Polistes crinitus and Mischocyttarus phthisicus). A side-by-side comparison of the endogenous period under constant darkness (free-running period) led us to the realization that these social insects exhibit significant deviations from the Earth's 24 h rotational period as well as a large degree of inter-individual variation compared with Drosophila. Experiments at different temperatures, using honey bees as a model, revealed that testing the endogenous rhythm at 35°C, which is the hive's core temperature, results in average periods closer to 24 h compared with 25°C (23.8 h at 35°C versus 22.7 h at 25°C). This finding suggests that the degree of tuning of circadian temperature compensation varies among different organisms. We expect that the commercial availability, cost-effectiveness and integrated nature of this monitoring system will facilitate the growth of the circadian field in these social insects and catalyze our understanding of the mechanisms as well as the functional and evolutionary relevance of circadian rhythms. [ABSTRACT FROM AUTHOR]

Background In social groups, dominant individuals may socially inhibit reproduction of subordinates using aggressive interactions or, in the case of highly eusocial insects, pheromonal communication. It has been hypothesized these two modes of reproductive inhibition utilize conserved pathways. Here, we use a comparative framework to investigate the chemical and genomic underpinnings of reproductive dominance in the primitively eusocial wasp Polistes metricus. Our goals were to first characterize transcriptomic and chemical correlates of reproductive dominance and second, to test whether dominance-associated mechanisms in paper wasps overlapped with aggression or pheromone-related gene expression patterns in other species. To explore whether conserved molecular pathways relate to dominance, we compared wasp transcriptomic data to previous studies of gene expression associated with pheromonal communication and queen-worker differences in honey bees, and aggressive behavior in bees, Drosophila, and mice. Results By examining dominant and subordinate females from queen and worker castes in early and late season colonies, we found that cuticular hydrocarbon profiles and genome-wide patterns of brain gene expression were primarily associated with season/social environment rather than dominance status. In contrast, gene expression patterns in the ovaries were associated primarily with caste and ovary activation. Comparative analyses suggest genes identified as differentially expressed in wasp brains are not related to queen pheromonal communication or caste in bees, but were significantly more likely to be associated with aggression in other insects (bees, flies), and even a mammal (mice). Conclusions This study provides the first comprehensive chemical and molecular analysis of reproductive dominance in paper wasps. We found little evidence for a chemical basis for reproductive dominance in P. metricus, and our transcriptomic analyses suggest that different pathways regulate dominance in paper wasps and pheromone response in bees. Furthermore, there was a substantial impact of season/social environment on gene expression patterns, indicating the important role of external cues in shaping the molecular processes regulating behavior. Interestingly, genes associated with dominance in wasps were also associated with aggressive behavior in bees, solitary insects and mammals. Thus, genes involved in social regulation of reproduction in Polistes may have conserved functions associated with aggression in insects and other taxa. [ABSTRACT FROM AUTHOR]

The insects known as thrips are commonly thought of as flower-living and pestiferous organisms, but we report here a novel interaction between a phlaeothripine thrips species, Mirothrips arbiter gen. et sp. nov. and three species of social paper wasps in Brazil. This thrips species breeds inside the wasp colonies, and larval and adult thrips feed on wasp eggs, which become severely damaged. Infested nests can contain up to 300 M. arbiter gen. et sp. nov. individuals. The closest relatives of M. arbiter are two presumably predaceous species: Mirothrips bicolor sp. nov., which inhabits abandoned Cecidomyiidae galls, and Mirothrips analis comb. nov., described from individuals collected in the silken bags of the caterpillars of Psychidae moths. The behaviour exhibited by M. arbiter represents one of the most evolutionarily advanced lifestyles known among Thysanoptera, and we predict that other polistine species serve as hosts for this thrips in Brazil. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 332-341. [ABSTRACT FROM AUTHOR]

Insect social parasites need to overcome host colonies’ defences to exploit their resources successfully. Sophisticated sensory deception mechanisms to break the host’s barriers have been repeatedly reported for many social parasites, possibly concealing the importance of open fighting, a more ancestral strategy. Understanding the relative importance of fooling and fighting is primarily challenging when the two strategies seem both available and advantageous. We focused on the paper wasp social parasite–host system Polistes sulcifer–P. dominulus, where both fooling and fighting have been suggested to play a role during usurpation contests. Host aggression is elicited by the chemical cues (hydrocarbons) that intruders bear on their cuticle. Parasites would benefit from reducing the amount of these cues before approaching the host colony. In addition, the parasites’ facial pattern has been shown to reduce the host’s aggressive reaction, probably by amplifying the mandibular width. We tested the occurrence of chemical and visual cheating through chemical analyses and laboratory usurpation trials, respectively. Usurping parasites did not conceal their identity by reducing cuticular hydrocarbons, nor did their facial pattern facilitate nest take-over. Contest outcome was instead predicted by the relative body size of the opponents. Fighting, rather than fooling, is therefore the strategy used by P. sulcifer usurping females. The importance of physical strength could thus explain why chemical or visual tricks do not play a role in taking over the host colony despite their potential usefulness. Our findings suggest that the evolution of sophisticated cheating mechanisms can be prevented by the ability to fight. [Copyright &y& Elsevier]

Abstract: Host antibacterial defense after Strepsiptera parasitization is a complex and rather unexplored topic. The way how these parasites interact with bacteria invading into the host insect during an infection is completely unknown. In the present study we demonstrate that larvae of the paper wasp Polistes dominulus are more efficient at eliminating bacteria when they are parasitized by the strepsipteran insect Xenos vesparum. We looked at the expression levels of the antimicrobial peptide defensin and we screened for the activity of other hemolymph components by using a zone of inhibition assay. Transcription of defensin is triggered by parasitization, but also by mechanical injury (aseptic injection). Inhibitory activity in vitro against the Gram positive bacterium Staphylococcus aureus is not influenced by the presence of the parasite in the wasp or by a previous immune challenge, suggesting a constitutive power of killing this bacterium by wasp hemolymph. Our results suggest either direct involvement of the parasite or that defensin and further immune components not investigated in this paper, for example other antimicrobial peptides, could play a role in fighting off bacterial infections in Polistes. [Copyright &y& Elsevier]

The paper wasp Polistes dominulus is unique among the social insects in that nearly one-third of co-foundresses are completely unrelated to the dominant individual whose offspring they help to rear and yet reproductive skew is high. These unrelated subordinates stand to gain direct fitness through nest inheritance, raising the question of whether their behaviour is adaptively tailored towards maximizing inheritance prospects. Unusually, in this species, a wealth of theory and empirical data allows us to predict how unrelated subordinates should behave. Based on these predictions, here we compare helping in subordinates that are unrelated or related to the dominant wasp across an extensive range of field-based behavioural contexts. We find no differences in foraging effort, defense behaviour, aggression or inheritance rank between unrelated helpers and their related counterparts. Our study provides no evidence, across a number of behavioural scenarios, that the behaviour of unrelated subordinates is adaptively modified to promote direct fitness interests. [ABSTRACT FROM AUTHOR]

Using demography data for the primitively eusocial wasp Ropalidia fasciata collected at 10 survey stations over 5 years, the effects of foundress group size (FGS) on colony survival rate and production of progeny were examined. The distribution pattern for the frequency of nests established by different numbers of foundresses fit a 0-truncated negative binomial distribution. The rate of nest failure up to the beginning of June decreased with FGS, and colony survival rate up to June and September increased with FGS. Although there were large variations among stations and years, the survival rate of colonies established by a single foundress (haplometrotic colonies) was significantly lower than that of colonies established by two or more foundresses (pleometrotic colonies). The number of new adults that emerged per colony up to the end of July increased with FGS, but there was no significant correlation between number of new adults per foundress and FGS. The number of potential foundresses produced per colony tended to increase with FGS, but there was no significant difference among the values produced per foundress for the three FGS categories. The percentage parasitism by an ichneumon parasitoid, Arthula formosana, tended to be higher in colonies established by a small number of foundresses. The relation between FGS and the productivity of the new foundresses was not statistically significant, suggesting that independent founding may be a better strategy for future subordinate foundresses. However, the long colony life span (mean 100 days, maximum 240 days) as compared with the shorter life span of foundresses (40 or 50 days) may be a good condition for the coexistence of many egg-layers in a colony. [ABSTRACT FROM AUTHOR]

Abstract: Several studies have shown that differences in the relative abundance of cuticular hydrocarbons occur between reproductives and non-reproductives in many social insects. These differences also exist between Polistes dominulus foundresses and their first emerged daughters (usually indicated as workers), but they gradually disappear when workers from orphaned colonies develop their ovaries and assume a reproductive role in the colony. However, hydrocarbons are not the exclusive components of cuticular layer of wasps. Mass-spectrometry analysis of cuticular methanol extracts from Polistes paper wasps showed a complex pattern of polar substances, partly or totally proteinaceous in nature. We found that these compounds, ranging from 918 to 2679Da, showed a clear caste differentiation between foundresses and their first emerged daughters (usually indicated as “workers”), both in queen-right and in orphaned colonies. Conversely to hydrocarbons, workers from orphaned colonies maintain a significant difference from foundresses in the pattern of the medium molecular weight (MW) polar compounds obtained by MALDI-TOF. On the basis of such results we hypothesize that a reliable cue to identify foundresses from daughters, and not only their reproductive status, may exist in Polistes wasps. Although the great majority of previous work on social insect communication has focused on cuticular hydrocarbons, our findings suggest that the medium MW component of cuticular substances may be involved in recognition. [Copyright &y& Elsevier]

Ropalidia marginata and Ropalidia cyathiformis are two Old World, primitively eusocial, tropical polistine wasps that exhibit perennial, aseasonal, indeterminate nesting cycles. Queens are periodically ousted and replaced by one of the workers, whom we refer to as the potential queen. Here we identify the characters of the potential queens by experimentally removing queens from several colonies of both species. Potential queens in R. marginata are unspecialized, worker-like individuals, not unique in their dominance ranks. In contrast, potential queens in R. cyathiformis are queenlike individuals and unique in always holding the top dominance rank among the workers. We suggest that this striking difference in the behaviour of the potential queens of the two species has to do with the very different mechanisms that queens of the two species use to suppress worker reproduction. In regard to their ovarian development, potential queens of neither species are unique and they are only one among several individuals with partially developed ovaries. This may have to do with the fact that queen replacements are frequent in tropical, aseasonal climates, making it adaptive for several individuals to be prepared to take over the position of the queen at short notice. [ABSTRACT FROM AUTHOR]

Abstract: The wasps of the genus Polistes (paper wasps), have a worldwide distribution and are widespread in human-built areas. Like other social wasps, they are at the top of food chains and are therefore exposed to the dangers of biomagnification, given that the larvae are fed predominantly with prey that consist of herbivorous insects. The larval faeces, larval fecal masses, in the form of a semi-solid ball, are made up of the residues of the diet of the larva, which are emitted and compressed on the floor of the cell during the larval metamorphosis. Larval fecal masses may accumulate lead (up to 36 times with respect to the adult body), therefore they were used as substrate for the analysis. From the analysis of sample nests of Polistes dominulus in various sites of the urban area of Florence, it emerges that the larval fecal masses are an analytical substrate with which it is possible to distinguish zones with differing degrees of lead pollution. The lead concentration measured in the larval fecal masses turns out to be directly correlated with vehicle traffic density, the main lead source in Florence when the survey was carried out. The notable increase in the lead concentration of larval fecal masses from the rural to the urban nest (11.15 times), in contrast with the much more limited level of pupae (4.39 times), seems to indicate the efficiency of the excretion and/or barrier mechanisms. These wasps seem to be a promising species for biomonitoring lead pollution in order to better understand its dynamics in anthropic ecosystems after the progressive diffusion of unleaded gasoline. [Copyright &y& Elsevier]

Abstract: Ropalidia marginata is a primitively eusocial, polistine wasp widely distributed in peninsular India. In spite of its primitively eusocial status, queens of R. marginata are surprisingly docile and behaviourally non-dominant (except during the first week or so of their careers as queens). Yet they successfully maintain reproductive monopoly throughout their careers, probably through the use of pheromones. Workers exhibit dominance–subordinate interactions but these behaviours are not involved in regulating reproductive competition among the workers because workers with high dominance ranks are not necessarily the ones who replace lost queens. We have speculated and provided correlational evidence before that dominance-subordinate interactions among the workers have been co-opted in this species for the workers to regulate each other''s foraging. Here, we provide experimental evidence in support of the speculation, by reducing demand for food and showing that this results in a significant decrease in the frequency of dominance-subordinate interactions among the workers. [Copyright &y& Elsevier]

We examined the population genetic structure of an extremely successful invasive wasp, Polistes dominulus. Although successful biological invasions of social insects have been associated with genetic bottlenecks, our research uncovered an unexpected level of genetic diversity in the northeastern U.S. invasion population. Compared with a previously studied European sample, the northeastern U.S. invasion population shows no significant reduction in gene diversity and no trace of a genetic bottleneck in the putative "introduction population." We identified multiple private microsatellite alleles in both Massachusetts and New York, which strongly suggests that the northeastern U.S.P. dominulus population arose from at least two independent introductions. Although a genetic bottleneck may enhance invasion success for some social insects, genetic and geographical data on this successful invader suggest that this wasp may represent the converse. Our results support immediate identification of genetic diversity in an invasion population before the occurrence of secondary introductions as an essential part of managing and controlling invasive species. [ABSTRACT FROM AUTHOR]

This study investigated the effects of alarm pheromone components on the heat production rates of hornets (Vespa crabro) by means of direct calorimetry. In a flow-through system, pheromones from hornets, honeybees (Apis mellifera) and yellowjackets (Vespula vulgaris) were sucked through a measuring vessel containing a group of hornet workers. The locomotive reaction of hornet workers was recorded as an increase of the heat production rate. Hornets exhibited a strong response to their own alarm pheromone components, mainly 2-methyl-3-butene-2-ol (MBO). They also reacted intensively upon the main alarm pheromone component of the honey bee, isopentylactetate (IPA), but less pronounced to alarm pheromone components of yellowjackets. The metabolic response of hornets to MBO was dose-dependent. The heat production rates of provoked hornet workers were similar to those of flying hornets. (z)-9-Pentacosene, a substance which is believed to be a thermoregulative brood pheromone, induced no metabolic reaction. [Copyright &y& Elsevier]

Reports on the keystone-like crystals found in the brood-rearing cells inside the nest combs of the hornet Vespa orientalis. Structure and composition of the crystals; Findings of the diffraction analysis made; Stages of comb building in social wasps.