Belgium

The characteristic buzz of bees, produced by their indirect (thoracic) flight muscles, has been extensively studied in the context of flight. In particular, many studies have investigated how the wingbeat frequency is influenced by abiotic factors such as air density, temperature, and humidity but is primarily constrained by biomechanical factors such as resonance of the thorax and the need to generate lift. However, these same muscles also produce vibrations in non-flight contexts, including communication, defence, and buzz-pollination. During these behaviours, the wings are decoupled from the system, providing a more direct route to assessing the determinants of muscle contraction frequency. Interestingly, mass-dependence is absent in non-flight buzzing, suggesting that other factors dominate when the wings are removed from the system. Here, we summarise multiple experiments on wild and lab-reared bumblebees to explore these factors. In particular, we demonstrate the role of thorax temperature in determining muscle biomechanics, and show that exposure to heavy metals, which interfere with calcium signalling, can reduce contraction frequency. We highlight that studying non-flight vibrations in bees provides valuable insights into asynchronous muscle function, offering a rich avenue for future research.

SEB Conference 2025

What determines the pitch of a bee&#39;s buzz?

arctic

entomology

muscles

pollutants

pollination

bombus

physiology

temperature

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What determines the pitch of a bee's buzz?

technical paper

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Temperature shapes phenotypic variation through effects at different levels and time-scales; changes in phenotype frequencies due to natural selection and changes in phenotype expression due to phenotypic plasticity. In particular, the temperature experienced during development can determine the production of distinct adult phenotypes from the same genotype; a phenomenon called thermal developmental plasticity. This plasticity can match phenotype to ecological conditions and help organisms to cope with environmental heterogeneity, including differences between alternating seasons. I will use two insect models of seasonal plasticity to illustrate the importance of thermal plasticity in studies of variation in organismal phenotypes, and of the impact of climate change in natural populations. Temperature (T) during development affects a series of adult traits which impact their fitness. Some of these traits are fixed throughout adult life (e.g. body size and pigmentation) while others can still respond to adult environmental conditions (e.g. behaviour and immunity). I will present date documenting these effects and how thermal plasticity depends on genetic (G) and environmental (E) context. These GxT and ExT interactions will affect how thermally plastic populations might cope and adapt to temperature perturbation.

Context-dependence of thermal plasticity in insects

Understanding how heat stress affects performance and reproductive fitness is essential for predicting the fate of species and populations. Our aim was to test phenotypic and reproductive responses to a heat wave in zebrafish (Danio rerio), and the potential role of DNA methylation in mediating these responses. We exposed wild-type and DNA methyltransferase 3a (DNMT3a) knock-out fish to a control temperature (25°C) and a +5°C heatwave for 28 days. Zebrafish acclimated to compensate swimming performance for warming. After re-acclimation at 25°C, the swimming performance of the heatwave-treated fish returned to pre-warming levels, indicating that thermal acclimation in adults is reversible. DNMT3a knock-out altered responses to heating, identifying DNA methylation as a mechanism underlying acclimation. Heatwave and genotype interacted to reduce the number of fertilised eggs produced (at one-tailed significance). Heating reduced offspring survival in wild-type fish, and survival was further reduced in DNMT3A knock-out fish. Our data show that despite acclimation compensating for heating, there was a reduction in reproductive success. Warming and disruption of DNA methylation by anthropogenic factors therefore can reduce fitness and potentially impact population size.

A heat wave induces compensatory acclimation of performance but reduces reproductive fitness

Freshwater ecosystems face growing threats from chemical pollution and climate warming. However, their combined effects on freshwater invertebrates remain poorly understood, particularly the mechanisms linking (sub)individual responses to broader ecological impacts.
To fill this gap, we assessed the effects of environmentally realistic concentrations of pharmaceutical contaminants (PhACs) and warming on freshwater invertebrates in outdoor mesocosms. We explored the physiological responses of Asellus aquaticus (Isopoda) and Cloeon dipterum (Ephemeroptera) in winter and summer, revealing seasonal differences in sensitivity: in winter, PhACs reduced energy availability and increased oxidative damage, while in summer, they boosted energy levels but reduced the population size. These physiological and population-level changes translated into ecosystem-level effects, including reduced leaf litter decomposition and altered insect emergence.
Building on these findings, we investigated the effects of a PhAC-and-pesticide mixture and warming to examine how sublethal effects of environmentally realistic pollutant mixtures cascade to population and ecosystem levels. Preliminary insights suggest that interactions between chemical stressors and warming drive unexpected shifts in zooplankton population size and structure, reinforcing the need to move beyond mortality-based assessments toward more ecologically relevant endpoints.
Our results highlight the vulnerability of aquatic invertebrates to warming in combination with low levels of pollution, demonstrating cascading impacts from individuals to ecosystems. These findings emphasize the need for integrative approaches to assess and mitigate the ecological consequences of emerging contaminants in a changing climate.

Sublethal Yet Significant: How Pollutants and Warming Impact Freshwater Invertebrates and Ecosystem Functioning

Photosynthesis is the workhorse for growth of all crops and is one of the key targets for improving agricultural productivity. Its efficiency differs both between and within species, with responses intensively measured under varying CO2  concentrations and light intensities (represented by A-Ci  and A-Q curves). While many published kinetic models of photosynthesis were used to simulate photosynthetic response and to propose different hypotheses, their kinetic parameters were collected from literature or estimated in different species. Yet, the differences in kinetic parameters of enzymes involved in photosynthesis between different genotypes are not fully explored. Moreover, photosynthetic traits are the integrated outcome of genetic factors, environmental conditions, and their complex interactions that renders their accurate prediction from genetic markers challenging. To address these problems, we parameterized a kinetic model for C4  photosynthesis allowing accurate simulation of A-Ci  or A-Q curves measured for 68 inbred lines from a maize population grown in two seasons. The genotype-specific kinetic parameters were then used to train a machine learning model capable of predicting parameter values for genotypes with only genomic data available. The predicted parameters were used to simulate photosynthesis for unseen genotypes and seasons by integrating environmental conditions. The photosynthetic rates simulated at saturating light using our approach, KineticGP, outperformed the predictions of baseline genomic models for unseen genotypes across seasons.

KineticGP, a computational framework for genomic prediction of leaf photosynthesis traits

Significant progress has been made in the field of plant genomics, as demonstrated by the increased use of high-throughput methodologies that enable the characterization of multiple genome-wide molecular phenotypes. These findings have provided valuable insights into plant traits and their underlying genetic mechanisms, particularly in model plant species. Nonetheless, effectively leveraging them to make accurate predictions represents a critical step in crop genomic improvement. We present AgroNT, a foundational large language model trained on genomes from 48 plant species with a predominant focus on crop species. We show that AgroNT can obtain state-of-the-art predictions for regulatory annotations, promoter/terminator strength, tissue-specific gene expression, and prioritize functional variants. We conduct a large-scale in silico saturation mutagenesis analysis on cassava to evaluate the regulatory impact of over 10 million mutations and provide their predicted effects as a resource for variant characterization. Finally, we propose the use of the diverse datasets compiled here as the Plants Genomic Benchmark (PGB), providing a comprehensive benchmark for deep learning-based methods in plant genomic research.

A foundational large language model for edible plant genomes

Increasing carbon dioxide, high temperatures, extreme weather, rising sea levels and increasing aridity will affect plant composition as well as their growth. Over 30% of crop plants are cyanogenic, capable of some level of cyanide release primarily as a herbivore deterrent.  Cassava is highly productive and an important food security crop. It is also the only staple that, under certain conditions, can kill you. A monotonous cassava diet is associated with a type of permanent paralysis called Konzo, particularly in children.  Most cyanogenic plants upregulate the production of cyanogenic glucosides when subject to stressful environmental conditions, leading to higher potential toxicity, in addition to the concentration effect from the overall biomass being less. It is proposed that the biosynthesis and recycling of these nitrogen-containing specialised metabolites help plants to manage their nitrogen and mitigate stress. Indeed, cassava (and sorghum) may have become more toxic with domestication. In this talk, I will discuss the possible underlying mechanisms as to why cassava, in particular, is so cyanogenic and why this may be exacerbated by climate change, using examples from field and controlled environment studies. I will propose strategies for reducing the harm , emphasising the need for education.

The poisonous plate of climate change

Bittersweet nightshade (Solanum dulcamara) plants produce a large variety of steroidal glycosides (SGs). Minor chemical differences, for example the level of saturation in the steroidal moiety, are associated with differences in resistance to herbivores and pathogens. Liquid Chromatography-quadrupole Time of Flight – Mass Spectrometry metabolomic analyses showed that both total leaf SG levels and SG diversity are associated with herbivore preference and leaf damage. We analysed the metabolomes of leaves and roots of selected chemotypes with saturated and unsaturated SG profiles in their leaves. In addition, we assessed the expression a GLYCOALKALOID METABOLISM25 (GAME25) homologue. In tomato, GAME25 is coding for a short-chain dehydrogenase responsible for the reduction of the C-5,6 double bond in dehydrotomatidine, which results in the formation of tomatidine. We found that differences in leaf SG chemodiversity were associated with the expression of SdGAME25. In contrast to leaves, roots of the same saturated and unsaturated individuals were more similar in their SG profiles and SdGAME25 expression levels. This implies that leaf and root SG chemodiversity in S. dulcamara are under differential selection pressures by aboveground and belowground interactions with herbivores and pathogens. In a common garden experiment, we manipulated the frequencies of these two S. dulcamara chemotypes to create different levels of SG plot chemodiversity. We found that both fruit and seed production as well as herbivore damage were affected by individual and plot diversity level. This suggest that herbivores as well as herbivore community composition may maintain chemodiversity as observed in natural S. dulcamara populations.

One beast's host plant is another beast's poison. Ecological consequences of steroidal glycoside diversity in Solanum dulcamara

Research on the photosynthetic response to environmental factors is mostly centred on light energy capture and carbon assimilation. Our understanding of how environmental factors impact photosynthate consumption (sink activity), and how these changes in sink activity affect the photosynthetic response is more limited. At the leaf level, consumption of photosynthates and sink limitations are usually quantified in terms of triose phosphate utilization (TPU). A big limitation to understanding the role of sink limitations on the photosynthetic response to environmental factors is the time-consuming steady state measurements needed to quantify TPU. Here, I present multi-species evidence supporting the Dynamic Assimilation Technique (DAT) as reliable and accurate non-steady state approach to the quantification of TPU and other biochemical limitations. I will further discuss the potential of using DATs approaches to estimate TPU proxies under 60 seconds using abrupt changes in CO2  concentrations. Field research suggested that the seasonal dynamics of carbon assimilation extend beyond concurrent environmental factors,  and sink activities strongly interacted with plant development to  ultimately limits photosynthesis. As we integrate multiple environmental factors in control environment experiments, plants’ internal carbon balance remains challenging to control and a potential source of variation. Experimental manipulation of sink strength in control environments suggested cross-level response in plant development, carbon partitioning and carbon assimilation. Results call for further consideration of carbon balance and sink limitations in photosynthetic research, and the development of rapid methods for leaf-level sink activity quantification.

Sink limitations to photosynthesis; how (and when) the end justify the means

Photosynthesis is a vital driver of plant growth and, under well-watered conditions, is inherently shaped by environmental factors such as light, temperature and CO2 . Recent advances in sensor technology and plant cuvette design enable detailed, real-time monitoring and modelling of dynamic photosynthetic responses under controlled conditions. These insights are not only key to mechanistic understanding but also serve as inspiration for optimizing plant growth in novel plant production systems. Yet, plant growth involves more than just the fixation of atmospheric carbon. It is a biophysical process also strongly governed by plant-water relations. Next-generation measurements and growth models must incorporate the dynamics of water transport and the crucial role of internal water storage pools in sustaining turgor pressure, especially under changing environmental conditions. This turgor-driven perspective is essential to fully understand how growth occurs, particularly under drought stress. To further complete this picture, we must also consider the often-overlooked recycling of internally respired CO₂, which becomes increasingly relevant under drought stress when stomatal closure limits atmospheric CO₂ uptake. Together, these processes highlight the intricate interplay between carbon and water relations in plants. Plants grow in a carbon-water world, and bridging the gap between controlled-environment experiments and real-world conditions requires embracing this complexity.

Plant growth on the bridge between carbon assimilation and water dynamics

The physiological mechanisms that underpin aquatic ectotherms’ ability to tolerate elevated temperatures have been long studied but remain largely unresolved due to the historical reductionism that has dominated biology for decades. However, recent advances in omics approaches are enabling us to acquire more comprehensive portraits of the way physiological systems function, have evolved and will respond to future environmental challenges. Particularly, integrated multi-omics analyses can provide an in-depth characterisation of the physiological status of organisms living under different environmental conditions. Polar marine ectotherms face important physiological challenges with the progression of ocean warming. Here we compared (as an ideal study system) the multi-omics response of an Arctic clam species to its more eurythermal temperate counterpart to a gradient of seven temperatures mimicking acute thermal conditions and marine heatwaves exposed under laboratory conditions. We measured survival after 12 days of exposure and sampled three tissues (gills, mantle, posterior adductor muscle), on which we performed targeted metabolomics (focussing particularly on energy metabolism) and untargeted lipidomics. Multivariate analyses combined with breakpoint analyses helped show that the lower tolerance observed under elevated temperatures in the Arctic species is underpinned by a limited ability for metabolomic rewiring, when compared to its temperate counterpart. The latter may rely on the activation of DNA repair and cell-signaling pathways. Further, we present the results for our lipidomic profiling and its multi-omics integration with metabolomics data to acquire a greater mechanistic understanding of the sensitivities of polar and temperate marine species to ocean warming.

Integrating metabolomics and lipidomics approaches to investigate the sensitivity of marine ectotherms from different climatic regimes to marine heatwaves

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Context-dependence of thermal plasticity in insects

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