Confirmed plenary speakers
Washington University in St. Louis, USA: Hamilton awardee 2026
The long reach of social insect research
Research on social insects has defined our understanding of how relatives interact when their often cooperative interests nevertheless have areas of conflict. Decades of work in areas like sex allocation, worker policing, kin discrimination, parent-offspring and sibling conflict, cannibalism, and eusociality have become clear largely from careful studies with social insects. Social insects are visible, easily marked and followed, and have clear behavioral interactions. Theory first elucidated in social insects has had a great impact in other areas from genomic imprinting to selfish genetic interests to microbial interactions. My own research began with following behavioral interactions among Polistes wasps. Much later, in collaboration with David Queller, I explored the conundrum of relatedness in swarm-founding wasps with multiple queens in Venezuela, genetic relatedness among primitively eusocial wasps and queen-worker conflict in stingless bees. But it was clear that the ideas that came from the cradle of social insects had much more to tell us about the natural world. Conflicts arise within individuals and among microbes, places where they would have been hard to discover. My own research turned to a social amoeba, Dictyostelium discoideum. I have applied ideas that come from social insects to this microbial system, first looking at interactions among amoebas and then turning to their interactions with bacterial symbionts. Social insects have also motivated more conceptual explorations into topics like what it means to be an organism. Here I will explore the past and future of ideas generated from studies of social insects.
Johannes Gutenberg Universität Mainz, Germany. West-Eberhard Awardee 2026
Non-senescing queens and the implications for the colony-level reproduction
Social insect queens break the rules in terms of energy budgeting combining long lifespans with high fertility. This can be resolved under colony-level evolution, with the optimization of the ageing and fertility of the germline over the soma. We showed that single-living queens of Cardiocondyla obscurior increase their investment into sexuals at the end of their life, and exhibit a below-average mortality until the peak of sexual production. Such delay in actuarial senescence, also found in seed-harvester ants and a termite, suggests that postponed ageing may be widespread among social insect reproductives. Supporting the delay of senescence, we find a contrasting pattern to any reported taxa: genes with middle-aged-biased expression exhibit a stronger purifying selection compared to younger-biased genes. Furthermore, we find no negative fitness effects in offspring fitness with increasing maternal age. These findings indicate that queens reproduce repeatedly while maintaining selection against senescence after sexual maturation due to late-life fitness gains. Although it remains unclear whether this mechanism is unique to superorganisms, it has broad implications for understanding healthspan, and the evolution of reproductive death. Colony-level selection also shapes the dynamics of growth, reproduction and dispersal. In polygynous species with mixed-aged queens, new colonies are founded by budding and are predominantly established by younger queens. This resembles assymmetric budding in yeast, where new cells separate with the rejuvenated genetic material, while older cells keep the accumulated DNA damage. We explore how staying or leaving a budding cohort influences colony growth and the distribution of reproductive potential within colonies.
Multidimensional assessment of emotional states in social insects
For a long time, social insects were considered simple reflexive automata, but they are now recognised as cognitively sophisticated organisms. Although cognitive sophistication does not automatically imply emotional experience, the recognition of social insect intelligence and behavioural flexibility raises a compelling question: might insects also experience basic emotions? Studying emotions in non-human animals is challenging because subjective experiences are not directly accessible. Therefore, adopting a functional, multicomponent framework, where emotional states are inferred from coordinated changes in behaviour, cognition, and physiology, is essential to advance the field without relying on subjective reports. This perspective supports the idea that insects may possess internal states functionally analogous to emotions, yet their systematic characterisation remains in its infancy. I will present our recent work applying this approach to honeybees and bumblebees, integrating behavioural, cognitive, physiological, and neurochemical evidence to characterise these states. Inspired by mammalian paradigms, such as fear conditioning and cognitive bias tests, we investigated whether insects exhibit fear-like responses to immediate or anticipated aversive stimuli, and how negative events influence attention and decision-making. While no single measure can distinguish between reflexive and genuine emotional responses, the convergence of behavioural, physiological, neurochemical, and cognitive evidence suggests that bees possess sustained, internally coordinated emotional states. Our findings further indicate that they share with vertebrates the core “building blocks” of affective states, namely valence, persistence, scalability, and global coordination, features widely regarded as hallmarks of emotions. These results have significant implications for our understanding of the evolution of emotions, invertebrate cognition, and welfare considerations.
Investigating the origin of eusociality in Hymenoptera
The evolution of eusociality from non-social ancestors in organisms such as bees and wasps is often thought of as one of the major evolutionary transitions. A division of labour, between reproductives (queens) that specialize on egg production and helpers (workers) that specialize on tasks such as foraging, is the key feature defining most forms of eusociality and is also thought to be the main reason why social insects are so successful ecologically. Research over recent decades has identified several genetic and ecological advantages of social nesting that should automatically favour helping when it first arises. Yet the reality is that only a small proportion of nest-building wasp and bee species are eusocial. The empirical study of how social behaviour evolves has naturally focussed on social taxa. However, this may not be appropriate for understanding the initial origin of sociality when, for example, morphological caste specialization will have been absent. Even in social taxa where females can still nest independently, helping probably originated >20 Myr ago, and such taxa indeed exhibit numerous derived features such as sophisticated dominance hierarchies and often linear correlations between group size and queen egg-laying rates. I will discuss experiments, observations and ideas about how non-eusocial taxa can help us understand what promotes and constrains the origin of eusociality, and likely scenarios for its evolution. At the same time, I emphasize the importance of continuing to investigate hitherto little-studied lineages rather than restricting the focus to a few ‘model’ taxa.
Shared ecological pressures and convergent co-option of ancient hormonal pathways underlie independent origins of eusociality
Social insects exhibit an extraordinary diversity of social forms, both within and among species. This behavioral variation is the product of both the underlying genes and the broader ecological factors that influence the costs and benefits of social living. Understanding social evolution requires a clear understanding of both mechanisms. Sweat bees have repeatedly gained and lost eusociality, providing replicated natural experiments to ask how social behavior arises and is modified. Our ecological and theoretical studies have revealed that season length and development time together shape social strategies: long seasons promote social nesting, short seasons favor solitary nesting, and intermediate seasons can support both. These model predictions match observed distributions across natural populations, revealing how ecological conditions can shape social variation in these bees. At the molecular level, we have identified convergent and complementary signatures of selection on a small number of sweat bee genes, including two primary proteins that bind and transport juvenile hormone (JH), an ancient regulator of insect development. We have shown that JH crosses the blood-brain barrier in both bees and ants, and that experimentally increasing brain JH influences caste-related foraging behaviors in ants. Ongoing single-nucleus transcriptomic analyses indicate that, across independent origins of eusociality, queens and workers exhibit shared, brain-wide differences in hormonal states as well as cell-type specific expression profiles. This suggests that hormonal access to the brain is a recurring substrate for social evolution across multiple insect lineages, and that ancient hormonal pathways can reshape social brains through differential action on conserved cellular targets. Taken together, our findings reveal how both ecological context and molecular mechanisms influence the evolution of eusociality.
Engineering a Queen: How Honey Bees Shape Development Through Architecture, Materials, and Collective Behavior
The remarkable ability of honey bee colonies to produce either workers or queens from genetically similar larvae has fascinated scientists for more than a century. While nutrition has long been considered the primary factor determining queen development, the potential role of the queen cell itself has received far less attention. In this lecture, I will present findings from our recent study published in Nature, which reveals an unexpected connection between queen cell architecture and honey bee queen development. Through a combination of behavioral observations, material analyses, and experimental manipulations, we investigated how worker bees construct queen cells and how the physical properties of these structures differ from those of regular worker comb cells. Our results demonstrate that queen cells are not simply enlarged versions of worker cells. Instead, they possess distinct structural and mechanical characteristics that influence the developmental environment of the queen larva. We further show that worker bees actively modify beeswax through specialized processing mechanisms, enabling the construction of these unique royal chambers. These findings challenge traditional views of caste development in honey bees and highlight the importance of nest architecture as an active component of developmental regulation. Beyond advancing our understanding of honey bee biology, this work provides new insights into how social insects shape developmental outcomes through the construction of specialized environments.
