A cytochrome P450 insecticide detoxification mechanism is not conserved across the Megachilidae family of bees

Recent work has demonstrated that many bee species have specific cytochrome P450 enzymes (P450s) that can efficiently detoxify certain insecticides. The presence of these P450s, belonging or closely related to the CYP9Q subfamily (CYP9Q-related), is generally well conserved across the diversity of bees. However, the alfalfa leafcutter bee, Megachile rotundata, lacks CYP9Q-related P450s and is 170-2500 times more sensitive to certain insecticides than bee pollinators with these P450s. The extent to which these findings apply to other Megachilidae bee species remains uncertain. To address this knowledge gap, we sequenced the transcriptomes of four Megachile species and leveraged the data obtained, in combination with publicly available genomic data, to investigate the evolution and function of P450s in the Megachilidae. Our analyses reveal that several Megachilidae species, belonging to the Lithurgini, Megachilini and Anthidini tribes, including all species of the Megachile genus investigated, lack CYP9Q-related genes. In place of these genes Megachile species have evolved phylogenetically distinct CYP9 genes, the CYP9DM lineage. Functional expression of these P450s from M. rotundata reveal they lack the capacity to metabolize the neonicotinoid insecticides thiacloprid and imidacloprid. In contrast, species from the Osmiini and Dioxyini tribes of Megachilidae have CYP9Q-related P450s belonging to the CYP9BU subfamily that are able to detoxify thiacloprid. These findings provide new insight into the evolution of P450s that act as key determinants of insecticide sensitivity in bees and have important applied implications for pesticide risk assessment.

Brood Parasites That Care: Alternative Nesting Tactics in a Subsocial Wasp

AbstractHosts and brood parasites are a classic example of conflict. Parasites typically provide no offspring care after laying eggs, imposing costs on hosts. Female subsocial wasps (Ammophila pubescens) alternate between initiating their own nests and using an "intruder" tactic of replacing eggs in nests of unrelated conspecifics. Hosts can respond by substituting new eggs of their own, with up to eight reciprocal replacements. Remarkably, intruders usually provision offspring in host nests, often alongside hosts. We used field data to investigate why intruders provision and to understand the basis of interactions. We found that intruders could not increase their fitness payoffs by using the typical brood parasite tactic of not provisioning offspring. Intruders using the typical tactic would benefit when hosts provisioned in their stead, but their offspring would starve when hosts failed to provision. Although some hosts obtained positive payoffs when intruders mistakenly provisioned their offspring, on average utilizing a conspecific nest represents parasitism: hosts pay costs while intruders benefit. Hosts and intruders used the same tactic of egg replacement, but intruders more often laid the final egg. Selection should favor better discrimination of offspring, which could lead to repeated cycles of costly egg replacement.

The dynamic interplay of dietary acid pH and concentration during early-stage human enamel and dentine erosion

Dental erosion continues to be a significant global health concern affecting nearly 30% of adults world-wide. With increasing soft drink consumption predominantly driving its prevalence, strategies for prevention and control are often implemented when erosion is severe, or rates are high in the populace. While factors affecting dental erosion such as pH on enamel has received much attention, the effect of dietary acid concentration when factored out to a commercially available pH has yet to be determined. Furthermore, understanding these effects on dentine, which is known to be more susceptible to erosion than enamel can unravel structure property relationships between acid characteristics and hard tissue types. This study aimed to develop structure-property relationships between dietary acid concentration, and pH, on the nano-textural and nano-mechanical properties of human enamel and dentine during short-term simulated drinking. To achieve this, a novel sample preparation methodology and analysis approach was developed by applying atomic force microscopy (AFM) in quantitative imaging mode. This enabled simultaneous measurement of enamel and dentine morphology and mechanical properties. Flow-cells were used to simulate drinking, exposing polished and smear layer free human enamel and dentine to 30 s repeated cycles of unbuffered citric acid 6% (pH = 1.88) and 1% (w/v) (pH = 2.55) and commercially available buffered pH = 3.8 states, for up to 180 s. The same 50 µm × 50 µm area of specimen morphology was analysed using in-house developed nanotextural analysis using the bearing area curve (BAC) with a focus on roughness (Ra), normalised peak (PA) and valley areas (VA). Mechanical properties were simultaneously measured for stiffness (N/m) after each 30 s. While all studies agree pH is a major factor in the erosion of enamel, here its dominance over the treatment time varied, with concentration surpassing the importance of pH after initial acid contact. Conversely, dentine erosion showed concentration-dependent changes in morpho-mechanical properties only. These results not only highlight the dynamic process of erosion, but how the interplay between acid characteristics and dental tissue type impact the progression of very early-stage erosion.

Sensory plasticity in a socially plastic bee

The social Hymenoptera have contributed much to our understanding of the evolution of sensory systems. Attention has focussed chiefly on how sociality and sensory systems have evolved together. In the Hymenoptera, the antennal sensilla are important for optimizing the perception of olfactory social information. Social species have denser antennal sensilla than solitary species, which is thought to enhance social cohesion through nestmate recognition. In the current study, we test whether sensilla numbers vary between populations of the socially plastic sweat bee Halictus rubicundus from regions that vary in climate and the degree to which sociality is expressed. We found population differences in both olfactory and hygro/thermoreceptive sensilla numbers. We also found evidence that olfactory sensilla density is developmentally plastic: when we transplanted bees from Scotland to the south-east of England, their offspring (which developed in the south) had more olfactory hairs than the transplanted individuals themselves (which developed in Scotland). The transplanted bees displayed a mix of social (a queen plus workers) and solitary nesting, but neither individual nor nest phenotype was related to sensilla density. We suggest that this general, rather than caste-specific sensory plasticity provides a flexible means to optimize sensory perception according to the most pressing demands of the environment. Sensory plasticity may support social plasticity in H. rubicundus but does not appear to be causally related to it.

Sisters doing it for themselves: extensive reproductive plasticity in workers of a primitively eusocial bee

Abstract

Plasticity is a key trait when an individual’s role in the social environment, and hence its optimum phenotype, fluctuates unpredictably. Plasticity is especially important in primitively eusocial insects where small colony sizes and little morphological caste differentiation mean that individuals may find themselves switching from non-reproductive to reproductive roles. To understand the scope of this plasticity, workers of the primitively eusocial sweat bee Lasioglossum malachurum were experimentally promoted to the reproductive role (worker-queens) and their performance compared with foundress-queens. We focussed on how their developmental trajectory as workers influenced three key traits: group productivity, monopolisation of reproduction, and social control of foraging nest-mates. No significant difference was found between the number of offspring produced by worker-queens and foundress-queens. Genotyping of larvae showed that worker-queens monopolised reproduction in their nests to the same extent as foundress queens. However, non-reproductives foraged less and produced a smaller total offspring biomass when the reproductive was a promoted worker: offspring of worker-queens were all males, which are the cheaper sex to produce. Greater investment in each offspring as the number of foragers increased suggests a limit to both worker-queen and foundress-queen offspring production when a greater quantity of pollen arrives at the nest. The data presented here suggest a remarkable level of plasticity and represent one of the first quantitative studies of worker reproductive plasticity in a non-model primitively eusocial species.

Significance statement

The ability of workers to take on a reproductive role and produce offspring is expected to relate strongly to the size of their colony. Workers in species with smaller colony sizes should have greater reproductive potential to insure against the death of the queen. We quantified the reproductive plasticity of workers in small colonies of sweat bees by removing the queen and allowing the workers to control the reproductive output of the nest. A single worker then took on the reproductive role and hence prevented her fellow workers from producing offspring of their own. These worker-queens produced as many offspring as control queens, demonstrating remarkable worker plasticity in a primitively eusocial species.

Paving the way for application of next generation risk assessment to safety decision-making for cosmetic ingredients

Next generation risk assessment (NGRA) is an exposure-led, hypothesis-driven approach that has the potential to support animal-free safety decision-making. However, significant effort is needed to develop and test the in vitro and in silico (computational) approaches that underpin NGRA to enable confident application in a regulatory context. A workshop was held in Montreal in 2019 to discuss where effort needs to be focussed and to agree on the steps needed to ensure safety decisions made on cosmetic ingredients are robust and protective. Workshop participants explored whether NGRA for cosmetic ingredients can be protective of human health, and reviewed examples of NGRA for cosmetic ingredients. From the limited examples available, it is clear that NGRA is still in its infancy, and further case studies are needed to determine whether safety decisions are sufficiently protective and not overly conservative. Seven areas were identified to help progress application of NGRA, including further investments in case studies that elaborate on scenarios frequently encountered by industry and regulators, including those where a ‘high risk’ conclusion would be expected. These will provide confidence that the tools and approaches can reliably discern differing levels of risk. Furthermore, frameworks to guide performance and reporting should be developed.

Sensitivity and Accumulation of Perfluorooctanesulfonate and Perfluorohexanesulfonic Acid in Fathead Minnows (Pimephales promelas) Exposed over Critical Life Stages of Reproduction and Development

Per- and polyfluoroalkyl substances (PFAS) have emerged as contaminants of environmental concern following release from industrial practices and use of aqueous film-forming foam (AFFF). Of the identified PFAS in surface water samples from known AFFF release sites, perfluorooctanesulfonate (PFOS) and perfluorohexanesulfonic acid (PFHxS) are frequently detected. The focus of the present study was to determine the effects of PFOS and PFHxS to the native (and common) fathead minnow, Pimephales promelas, over critical life stages of reproduction and development. Two separate, 42-d experiments were carried out using sexually mature fish, exposed to either PFOS or PFHxS. Measured exposure concentrations for PFOS and PFHxS were 0, 44, 88, 140, and 231 µg/L and 0, 150, 300, 600, and 1200 µg/L, respectively. At day 21 of the adult exposure, eggs were collected and reared for 21 d to determine the effects of PFOS or PFHxS on development, growth, and survival of larvae. The no-observable-effect concentration (NOEC) for PFOS was 44 µg/L, and the lowest-observable-effect concentration was 88 µg/L based on reduced growth in juvenile (F1) fish. Effects from PFOS exposures that did not follow a standard dose-response curve were reduced gonadosomatic index in adult males (at 44 µg/L) and reduced fecundity in females (at 140 µg/L). There was no toxicity on apical endpoints to report on adult or juvenile fish exposed to PFHxS up to 1200 µg/L. Importantly, we note that both PFOS and PFHxS accumulated in gonads and liver of adult fish following the respective exposures. The present study supports previous literature on PFOS toxicity and accumulation in fathead minnows but resulted in a lower NOEC than previously established for this species. Environ Toxicol Chem 2021;40:811-819. © 2020 SETAC.

Simple trapeziectomy versus trapeziectomy with flexor carpi radialis suspension: a 17-year follow-up of a randomized blind trial

The purpose of this study was to investigate if there were any significant differences in the long-term outcomes of patients who participated in a randomized trial of trapeziectomy alone compared with trapeziectomy with ligament reconstruction and tendon interposition (LRTI). Sixty-five patients were invited for a follow-up visit at a mean of 17 years (range 15-20) postoperatively. Twenty-eight patients attended, who had 34 operations, 14 trapeziectomy alone and 20 with LRTI. There were no statistically significant differences between the two groups in terms of satisfaction with surgery or functional outcomes, with most measurements showing minimal or no differences in means between the two groups. There was no difference in the space between the metacarpal and scaphoid. Radial abduction was the only parameter that was significantly greater in the patients with simple trapeziectomy (median 79°) compared with trapeziectomy with LRTI (median 71°) (p = 0.04). Even at 17 years there is no significant benefit of LRTI over trapeziectomy alone for thumb carpometacarpal joint osteoarthritis.Level of evidence: I.

O-Health-Edu: Advancing oral health: A vision for dental education

The prevalence and burden of untreated oral diseases throughout the life course remains high worldwide, and inequalities in oral health and dental care are increasing. This is a major public health issue that is not being enough addressed by the health care systems. To better manage populations' oral health, oral health professionals must be trained to adapt to population needs and societal and technological changes. Furthermore, dental institutions must fulfill their social responsibility by prioritizing educational and research activities that promote advancing individual and community health. In Europe, great variability exists between dental programs within the same country or between countries. This variability is an issue as European graduates can practice around the European Union through mutual recognition of their qualifications. This might lead to inequities in the availability, accessibility, acceptability and quality of health services. The convergence of competencies and quality standards at the international level must thus be better clearly identified, defined and improved. The purpose of the O-Health-Edu, EU funded project, “Advancing Oral Health: A vision for Dental Education” is thus to assess the current situation concerning the oral health professionals' education (OHP) and to identify educational priorities so that future graduating OHPs have competencies aligned with emerging population needs. The project is supported within the KA203 - “Cooperation for Innovation and the Exchange of Good Practices - Strategic Partnerships for higher education” Erasmus program. It began in October 2019 for three years, with eight European university partners and the ADEE (Association for Dental Education in Europe). The firsts steps consist of a scoping review to identify the available information followed by a questionnaire survey to gather more comprehensive data so that to build an opened data source, and a glossary of dental education terms.

Key messages

Few Information about the current situation of dental education in Europe. Graduates must be equipped with adequate competencies to face populations needs.

The evolution of parental care strategies in subsocial wasps

Abstract

Insect parental care strategies are particularly diverse, and prolonged association between parents and offspring may be a key precursor to the evolution of complex social traits. Macroevolutionary patterns remain obscure, however, due to the few rigorous phylogenetic analyses. The subsocial sphecid wasps are a useful group in which to study parental care because of the diverse range of strategies they exhibit. These strategies range from placing a single prey item in a pre-existing cavity to mass provisioning a pre-built nest, through to complex progressive provisioning where a female feeds larvae in different nests simultaneously as they grow. We show that this diversity stems from multiple independent transitions between states. The strategies we focus on were previously thought of in terms of a stepping-stone model in which complexity increases during evolution, ending with progressive provisioning which is a likely precursor to eusociality. We find that evolution has not always followed this model: reverse transitions are common, and the ancestral state is the most flexible rather than the simplest strategy. Progressive provisioning has evolved several times independently, but transitions away from it appear rare. We discuss the possibility that ancestral plasticity has played a role in the evolution of extended parental care.

Significance statement

Parental care behaviour leads to prolonged associations between parents and offspring, which is thought to drive the evolution of social living. Despite the importance of insect parental care for shaping the evolution of sociality, relatively few studies have attempted to reconstruct how different strategies evolve in the insects. In this study, we use phylogenetic methods to reconstruct the evolution of the diverse parental care strategies exhibited by the subsocial digger wasps (Sphecidae). Contrary to expectations, we show that parental care in this group has not increased in complexity over evolutionary time. We find that the ancestral state is not the simplest, but may be the most flexible strategy. We suggest that this flexible ancestral strategy may have allowed rapid response to changing environmental conditions which might explain the diversity in parental care strategies that we see in the digger wasps today.

The evolution of eusociality: no risk-return tradeoff but the ecology matters

The origin of eusociality in the Hymenoptera is a question of major interest. Theory has tended to focus on genetic relatedness, but ecology can be just as important a determinant of whether eusociality evolves. Using the model of Fu et al. (2015), we show how ecological assumptions critically affect the conclusions drawn. Fu et al. inferred that eusociality rarely evolves because it faces a fundamental ‘risk‐return tradeoff’. The intuitive logic was that worker production represents an opportunity cost because it delays realising a reproductive payoff. However, making empirically justified assumptions that (1) workers take over egg‐laying following queen death and (2) productivity increases gradually with each additional worker, we find that the risk‐return tradeoff disappears. We then survey Hymenoptera with more specialised morphological castes, and show how the interaction between two common features of eusociality – saturating birth rates and group size‐dependent helping decisions – can determine whether eusociality outperforms other strategies.

Partner choice correlates with fine scale kin structuring in the paper wasp Polistes dominula

Cooperation among kin is common in animal societies. Kin groups may form by individuals directly discriminating relatives based on kin recognition cues, or form passively through natal philopatry and limited dispersal. We describe the genetic landscape for a primitively eusocial wasp, Polistes dominula, and ask whether individuals choose cooperative partners that are nearby and/or that are genetic relatives. Firstly, we genotyped an entire sub-population of 1361 wasps and found genetic structuring on an extremely fine scale: the probability of finding genetic relatives decreases exponentially within just a few meters of an individual's nest. At the same time, however, we found a lack of genetic structuring between natural nest aggregations within the population. Secondly, in a separate dataset where ~2000 wasps were genotyped, we show that wasps forced experimentally to make a new nest choice tended to choose new nests near to their original nests, and that these nests tended to contain some full sisters. However, a significant fraction of wasps chose nests that did not contain sisters, despite sisters being present in nearby nests. Although we cannot rule out a role for direct kin recognition or natal nest-mate recognition, our data suggest that kin groups may form via a philopatric rule-of-thumb, whereby wasps simply select groups and nesting sites that are nearby. The result is that most subordinate helpers obtain indirect fitness benefits by breeding cooperatively.

Parental manipulation of offspring size in social groups: a test using paper wasps

Abstract

Maternal effects should be especially likely when mothers actively provision offspring with resources that influence offspring phenotype. In cooperatively breeding and eusocial taxa, there is potential for parents to strategically manipulate offspring phenotype in their own interests. Social insect queens are nearly always larger than their worker offspring, and queens could benefit by producing small daughter workers in several ways. If queens use aggression to dominate or coerce workers, a queen producing small workers might minimize potential conflict or competition from her offspring. In addition, because of the trade-off between the number of workers she is able to produce and their individual size, a queen may produce small workers to optimize colony work effort. In this study, we investigate why queens of the primitively eusocial paper wasp Polistes gallicus limit the size of their workers. We created queen–worker size mismatches by cross-fostering queens between nests. We then tested whether the queen–worker size difference affects worker foraging and reproductive effort, or the amount of aggression in the group. Some of our results were consistent with the idea that queens limit worker size strategically: small workers were no less successful foragers, so that producing a larger number of smaller workers may overall increase queen fitness. We found that queens were less likely to attack large workers, perhaps because attempting to coerce large workers is riskier. However, larger workers did not forage less, did not invest more in ovarian development, and were not more aggressive themselves. There was therefore little evidence overall that queens limit conflict by producing smaller workers.

Significance statement

In social animals, parents might manipulate phenotypic traits of their offspring in their own interests. In paper wasps (Polistes), the first offspring produced are smaller than the queen and become workers: instead of founding their own nests, they stay and help their mother to rear new queens and males. We investigated whether P. gallicus queens could benefit by producing small daughter workers by using cross-fostering to create size mismatches between queens and their offspring. We then recorded foraging activity, reproductive effort, and aggression on nests. Queens were less likely to attack larger workers, but overall, there was limited evidence of size-based queen–worker conflict. However, because small workers were no less successful foragers, producing a larger number of smaller workers may optimize colony work effort.

Crozier's Effect and the Acceptance of Intraspecific Brood Parasites

Organisms can often benefit by distinguishing between different classes of individuals. An example is kin recognition, whereby individuals preferentially associate with or aid genetic relatives that bear matching recognition cues but reject others. Despite its potential benefits, however, kin recognition using genetically based cues is often weak or absent [1-4]. A general explanation, termed "Crozier's effect," is that when individuals interact randomly, rarer cue alleles less often match cues of other individuals, and so are involved predominantly in "reject"-type interactions. If such interactions are more costly, positive frequency-dependent selection will erode the cue diversity upon which discrimination depends [4, 5]. Although widely cited [1, 2, 4, 6-9], this idea lacks rigorous testing in the field. Here, we show how Crozier's effect applies to interactions between hosts and conspecific parasites, and measure it using field data. In the wasp we studied, conspecific parasitism fits a key assumption of Crozier's model: the same females act as both hosts and parasites. By exchanging offspring between nests experimentally, we find no evidence that females respond to genetically based cues associated with foreign offspring. Through measuring costs and benefits, however, we demonstrate a strong Crozier effect: because more parental investment is wasted when foreign offspring are rejected, interactions involving rejection have substantially lower payoffs than interactions involving acceptance. Costly rejection can thus eliminate cue diversity by causing selection against rare cue alleles, consistent with the absence of genetically based recognition that we observe. Females instead appear to rely on non-genetic cues that enable them to detect less than half of parasitic offspring.

A Type 1 Diabetes Genetic Risk Score Predicts Progression of Islet Autoimmunity and Development of Type 1 Diabetes in Individuals at Risk

OBJECTIVE

We tested the ability of a type 1 diabetes (T1D) genetic risk score (GRS) to predict progression of islet autoimmunity and T1D in at-risk individuals.

RESEARCH DESIGN AND METHODS

We studied the 1,244 TrialNet Pathway to Prevention study participants (T1D patients' relatives without diabetes and with one or more positive autoantibodies) who were genotyped with Illumina ImmunoChip (median [range] age at initial autoantibody determination 11.1 years [1.2-51.8], 48% male, 80.5% non-Hispanic white, median follow-up 5.4 years). Of 291 participants with a single positive autoantibody at screening, 157 converted to multiple autoantibody positivity and 55 developed diabetes. Of 953 participants with multiple positive autoantibodies at screening, 419 developed diabetes. We calculated the T1D GRS from 30 T1D-associated single nucleotide polymorphisms. We used multivariable Cox regression models, time-dependent receiver operating characteristic curves, and area under the curve (AUC) measures to evaluate prognostic utility of T1D GRS, age, sex, Diabetes Prevention Trial-Type 1 (DPT-1) Risk Score, positive autoantibody number or type, HLA DR3/DR4-DQ8 status, and race/ethnicity. We used recursive partitioning analyses to identify cut points in continuous variables.

RESULTS

Higher T1D GRS significantly increased the rate of progression to T1D adjusting for DPT-1 Risk Score, age, number of positive autoantibodies, sex, and ethnicity (hazard ratio [HR] 1.29 for a 0.05 increase, 95% CI 1.06-1.6; P = 0.011). Progression to T1D was best predicted by a combined model with GRS, number of positive autoantibodies, DPT-1 Risk Score, and age (7-year time-integrated AUC = 0.79, 5-year AUC = 0.73). Higher GRS was significantly associated with increased progression rate from single to multiple positive autoantibodies after adjusting for age, autoantibody type, ethnicity, and sex (HR 2.27 for GRS >0.295, 95% CI 1.47-3.51; P = 0.0002).

CONCLUSIONS

The T1D GRS independently predicts progression to T1D and improves prediction along T1D stages in autoantibody-positive relatives.

Environmental barriers to sociality in an obligate eusocial sweat bee

Understanding the ecological and environmental contexts in which eusociality can evolve is fundamental to elucidating its evolutionary origins. A sufficiently long active season is postulated to have been a key factor facilitating the transition to eusociality. Many primitively eusocial species exhibit an annual life cycle, which is thought to preclude the expression of eusociality where the active season is too short to produce successive worker and reproductive broods. However, few studies have attempted to test this idea experimentally. We investigated environmental constraints on the expression of eusociality in the obligate primitively eusocial sweat bee Lasioglossum malachurum, by transplanting nest foundresses from the south to the far north of the United Kingdom, far beyond the natural range of L. malachurum. We show that transplanted bees can exhibit eusociality, but that the short length of the season and harsher environmental conditions could preclude its successful expression. In one year, when foundresses were transplanted only after provisioning first brood (B1) offspring, workers emerged in the north and provisioned a second brood (B2) of reproductives. In another year, when foundresses were transplanted prior to B1 being provisioned, they were just as likely to initiate nesting and provisioned just as many B1 cells as foundresses in the south. However, the life cycle was delayed by approximately 7 weeks and nests suffered 100% B1 mortality. Our results suggest that short season length together with poor weather conditions represent an environmental barrier to the evolution and expression of eusociality in sweat bees.

Predictors of nest growth: diminishing returns for subordinates in the paper wasp Polistes dominula

ABSTRACT

In cooperative breeders, subordinates that have alternative reproductive options are expected to stay and help dominant breeders only as long as they contribute to group productivity, if their fitness is linked with colony success. Female Polistes dominula paper wasps live as cooperative breeders in small groups of typically fewer than 10 females. Subordinates tend to have high-quality outside options, and so could choose alternative breeding tactics if their work efforts increased productivity negligibly. In the founding stage before workers emerge, we tested the effect of various predictors on nest growth, as a proxy for group productivity, and explored the shape of the relationship between group size and nest growth. We found group size to be the only significant predictor of nest growth: variation among body sizes within the group showed no effect, suggesting a lack of size-dependent task specialization in this species. Average body size and average genetic relatedness between group members similarly showed no effects on nest growth. Group size had a non-linear effect so that per-capita benefits to nest growth decreased in larger groups, and groups of 10 or more would benefit negligibly from additional group members. Hence, females might be better off pursuing other options than joining a large group. This finding helps to explain why P. dominula groups are usually relatively small in our study population. Further studies may illuminate the mechanisms behind the smaller per-capita nest growth that we found in larger groups.

SIGNIFICANCE STATEMENT

Identifying which factors influence the productivity of animal groups is key to understanding why different species breed cooperatively in groups of varying sizes. In the paper wasp Polistes dominula, we investigated the growth rate of nests as a measure of group productivity. We found that average body size, the variation in body sizes within the group, and average genetic relatedness between group members did not affect nest growth, while group size had a strong, positive effect: nests grew faster with more group members, but the per-capita benefit decreased in larger groups. The addition of extra group members in groups of 10 or more had negligible effects on nest growth. Hence, wasps may be better off pursuing other options than joining large groups. This finding helps to explain why groups normally consist of fewer than 10 wasps in this population.

Curriculum content and assessment of pre-clinical dental skills: A survey of undergraduate dental education in Europe

INTRODUCTION

Since 1981, the qualifications for various healthcare professionals across the European Union have enjoyed mutual recognition in accordance with the EU Directive 81/1057/EEC. Whilst the directive includes dental practitioners, it is recognised that significant variation exists in curriculum structure, content and scope of practice across institutions. This article aimed to explore pan-European practice in relation to curriculum content, teaching and learning strategies and assessment of pre-clinical dental skills.

METHOD

A request to complete an online questionnaire, in English, was sent electronically to skills leads at all Association of Dental Education in Europe member schools. The questionnaire collected information in relation to institution and country, regulatory requirements to demonstrate safety, details of specific pre-clinical skills courses, learning materials and teaching staff.

RESULTS

Forty-eight institutions, from 25 European countries responded. Seven countries (n=7, 28%) reported no requirement to demonstrate student operative safety prior to patient treatment. Several core and operative clinical skills are common to the majority of institutions. The most commonly taught core skills related directly to the clinical environment such as cross-infection control and hand washing. The least common were skills that indirectly related to patient care, such as communication skills and working as a team.

CONCLUSION

There are clear differences within European pre-clinical dental education, and greater efforts are needed to demonstrate that all European students are fit to practice before they start treating patients. Learning outcomes, teaching activities and assessment activities of pre-clinical skills should be shared collaboratively to further standardise curricula.

Building a new research framework for social evolution: intralocus caste antagonism

The breeding and non‐breeding ‘castes’ of eusocial insects provide a striking example of role‐specific selection, where each caste maximises fitness through different morphological, behavioural and physiological trait values. Typically, queens are long‐lived egg‐layers, while workers are short‐lived, largely sterile foragers. Remarkably, the two castes are nevertheless produced by the same genome. The existence of inter‐caste genetic correlations is a neglected consequence of this shared genome, potentially hindering the evolution of caste dimorphism: alleles that increase the productivity of queens may decrease the productivity of workers and vice versa, such that each caste is prevented from reaching optimal trait values. A likely consequence of this ‘intralocus caste antagonism’ should be the maintenance of genetic variation for fitness and maladaptation within castes (termed ‘caste load’), analogous to the result of intralocus sexual antagonism. The aim of this review is to create a research framework for understanding caste antagonism, drawing in part upon conceptual similarities with sexual antagonism. By reviewing both the social insect and sexual antagonism literature, we highlight the current empirical evidence for caste antagonism, discuss social systems of interest, how antagonism might be resolved, and challenges for future research. We also introduce the idea that sexual and caste antagonism could interact, creating a three‐way antagonism over gene expression. This includes unpacking the implications of haplodiploidy for the outcome of this complex interaction.

Biological markets in cooperative breeders: quantifying outside options

A major aim in evolutionary biology is to understand altruistic help and reproductive partitioning in cooperative societies, where subordinate helpers forego reproduction to rear dominant breeders' offspring. Traditional models of cooperation in these societies typically make a key assumption: that the only alternative to staying and helping is solitary breeding, an often unfeasible task. Using large-scale field experiments on paper wasps (Polistes dominula), we show that individuals have high-quality alternative nesting options available that offer fitness payoffs just as high as their actual chosen options, far exceeding payoffs from solitary breeding. Furthermore, joiners could not easily be replaced if they were removed experimentally, suggesting that it may be costly for dominants to reject them. Our results have implications for expected payoff distributions for cooperating individuals, and suggest that biological market theory, which incorporates partner choice and competition for partners, is necessary to understand helping behaviour in societies like that of P. dominula. Traditional models are likely to overestimate the incentive to stay and help, and therefore the amount of help provided, and may underestimate the size of reproductive concession required to retain subordinates. These findings are relevant for a wide range of cooperative breeders where there is dispersal between social groups.

Identification of 24 new microsatellite loci in the sweat bee Lasioglossum malachurum (Hymenoptera: Halictidae)

Objective

The objective here is to identify highly polymorphic microsatellite loci for the Palaearctic sweat bee Lasioglossum malachurum. Sweat bees (Hymenoptera: Halictidae) are widespread pollinators that exhibit an unusually large range of social behaviours from non-social, where each female nests alone, to eusocial, where a single queen reproduces while the other members of the colony help to rear her offspring. They thus represent excellent models for understanding social evolution.

Results

24 new microsatellite loci were successfully optimized. When amplified across 23–40 unrelated females, the number of alleles per locus ranged from 3 to 17 and the observed heterozygosities 0.45 to 0.95. Only one locus showed evidence of significant deviation from Hardy–Weinberg equilibrium. No evidence of linkage disequilibrium was found. These 24 loci will enable researchers to gain greater understanding of colony relationships within this species, an important model for the study of eusociality. Furthermore, 22 of the same loci were also successfully amplified in L. calceatum, suggesting that these loci may be useful for investigating the ecology and evolution of sweat bees in general.

Market forces influence helping behaviour in cooperatively breeding paper wasps

Biological market theory is potentially useful for understanding helping behaviour in animal societies. It predicts that competition for trading partners will affect the value of commodities exchanged. It has gained empirical support in cooperative breeders, where subordinates help dominant breeders in exchange for group membership, but so far without considering one crucial aspect: outside options. We find support for a biological market in paper wasps, Polistes dominula. We first show that females have a choice of cooperative partners. Second, by manipulating entire subpopulations in the field, we increase the supply of outside options for subordinates, freeing up suitable nesting spots and providing additional nesting partners. We predicted that by intensifying competition for help, our manipulation would force dominants to accept a lower price for group membership. As expected, subordinates reduce their foraging effort following our treatments. We conclude that to accurately predict the amount of help provided, social units cannot be viewed in isolation: the surrounding market must also be considered.

In cooperatively breeding species, subordinates help to raise the dominant breeders' offspring in return for benefits associated with group membership. Here, Grinsted and Field show that the amount of help provided by subordinate paper wasps depends on the availability of alternative nesting options, as predicted by biological market theory.

Resolving hot spot microstructure using x-ray penumbral imaging (invited)

We have developed and fielded x-ray penumbral imaging on the National Ignition Facility in order to enable sub-10 μm resolution imaging of stagnated plasma cores (hot spots) of spherically shock compressed spheres and shell implosion targets. By utilizing circular tungsten and tantalum apertures with diameters ranging from 20 μm to 2 mm, in combination with image plate and gated x-ray detectors as well as imaging magnifications ranging from 4 to 64, we have demonstrated high-resolution imaging of hot spot plasmas at x-ray energies above 5 keV. Here we give an overview of the experimental design criteria involved and demonstrate the most relevant influences on the reconstruction of x-ray penumbral images, as well as mitigation strategies of image degrading effects like over-exposed pixels, artifacts, and photon limited source emission. We describe experimental results showing the advantages of x-ray penumbral imaging over conventional Fraunhofer and photon limited pinhole imaging and showcase how internal hot spot microstructures can be resolved.

Cooperation between non-relatives in a primitively eusocial paper wasp, Polistes dominula

In cooperatively breeding vertebrates, the existence of individuals that help to raise the offspring of non-relatives is well established, but unrelated helpers are less well known in the social insects. Eusocial insect groups overwhelmingly consist of close relatives, so populations where unrelated helpers are common are intriguing. Here, we focus on Polistes dominula-the best-studied primitively eusocial wasp, and a species in which nesting with non-relatives is not only present but frequent. We address two major questions: why individuals should choose to nest with non-relatives, and why such individuals participate in the costly rearing of unrelated offspring. Polistes dominula foundresses produce more offspring of their own as subordinates than when they nest independently, providing a potential explanation for co-founding by non-relatives. There is some evidence that unrelated subordinates tailor their behaviour towards direct fitness, while the role of recognition errors in generating unrelated co-foundresses is less clear. Remarkably, the remote but potentially highly rewarding chance of inheriting the dominant position appears to strongly influence behaviour, suggesting that primitively eusocial insects may have much more in common with their social vertebrate counterparts than has commonly been thought.