Biology subjects

Lihoreau, M.

Publications and source records attributed to Lihoreau, M..

At least 19 recordsLinked to original sources

bioRxiv2026

Nutritional responses of bumblebees to thermal stress

Extreme climatic events impose considerable stress on organisms with consequences for key ecological interactions such as pollination. Because temperature directly affects metabolic processes, heat variations may also importantly influence the nutritional needs and feeding choices of animals. Here, we studied the effects of thermal stress on the nutritional choices and performances of bumblebees, using a 3D nutritional geometry design. At optimal temperature for colony development (30{degrees}C), bees successfully balanced carbohydrate, protein, and lipid collection, at levels beneficial for body weight and survival. Under cold stress (20{degrees}C), bees reduced their overall nutrient collection while selecting proportionally more carbohydrates, thereby prioritizing survival over weight gain. Under heat stress (35{degrees}C), nutrient balancing was disrupted and survival dropped. Notably however, across all temperatures, bees maintained stable lipid collection while flexibly adjusting the amount of carbohydrates and proteins, suggesting strong constraints on lipid regulation. Given the pivotal role of bees for pollination, identifying how their nutritional needs change in response to climatic conditions is of prior importance for food safety and the conservation of terrestrial ecosystems.

animal behavior and cognition↗

bioRxiv2026

Cognitive decline in aging parasitoid wasps

Aging induces cognitive decline in humans and some other animals. For species that rely on learning and memory for reproduction, impaired cognitive functions may incur severe fitness costs. Here we report age-related cognitive decline in a solitary parasitoid wasp, Venturia canescens, that uses olfactory memories for host seeking and selection. We trained individual wasps to associate an odour with an oviposition reward, and compared their learning and memory performances at different stages of the reproductive life. Wasps between 6- and 14-day-old showed consistently poorer learning and reduced memory retention than young conspecifics, and this tendency increased with age. In this parasitoid insect, aging induces a precocious cognitive decline in reproductive females, which could severely impact their fitness through altered abilities to identify high quality hosts.

animal behavior and cognition↗

bioRxiv2025

Social attraction mediates collective foraging decisions in invasive hornets

Group-living animals commonly use social information to better locate and exploit resources. In many insects, birds, fish and mammals, this can lead to collective foraging decisions by which animals share a single food source among alternatives of equal qualities. Here, we report collective foraging decisions in a social wasp, the yellow-legged hornet Vespa velutina nigrithorax, a major predator of bees and other terrestrial invertebrates invasive across Asia, Europe and North America. When given a choice between two identical liquid food sources (feeders or traps containing sugar solutions), wild hornets distributed asymmetrically on the two options, and this phenomenon was more frequent as group size increased. Priming one of the food sources with dead hornets predictably biased the collective choices towards this particular option, irrespective of whether the dead insects were conspecifics or hornets from a closely related species. Inter-attraction in yellow-legged hornets is thus a passive and non-specific mechanism, possibly mediated by visual or chemical cues displayed by dead hornets. This collective behaviour may provide important foraging advantages to hornets invading new territories and bring new perspectives for population control.

animal behavior and cognition↗

bioRxiv2025

Human performance in the Traveling Salesman Problem is influenced by spatial scale

Like many other animals, we humans frequently face complex route optimization problems when planning journeys between multiple locations. Several strategies can be employed to approach such Traveling Salesman Problems. However, these may be strongly constrained by spatial scales, for instance if the goal is to navigate in a supermarket, in a city, or across a continent. Here, we monitored the route optimization performances of human subjects collecting objects in a video game simulating 3D environments at various spatial scales. Unexpectedly, route optimization performances peaked at intermediate spatial scales, where participants could use global optimization strategies. At very large and very small spatial scales, however, participants predominantly employed less efficient local optimization strategies. At the very large scale, the considerable distances between objects prevented them from being seen all at once, making global planning difficult. At the very small scale, participants reported having chosen the shortest path, although they did not. This mismatch between perceived and actual performances suggests suboptimal alternatives were sufficiently short to be considered equivalent to the optimal route. Spatial scale thus strongly influences route planning in human navigators and may determine the spatial behaviors of a wide range of animals facing similar routing problems in their everyday lives.

animal behavior and cognition↗

bioRxiv2025

Male bumblebees adapt foraging to environmental conditions to sustain mate-seeking efforts

Male bees navigate complex trade-offs between energy acquisition and reproductive signalling, yet their movement strategies remain understudied. Unlike workers that optimise foraging to support the colony, males forage independently to collect nectar and deposit sex pheromones on selected plants. Using high-resolution 3D tracking in an indoor flight cage, we investigated how the spatial arrangement of nectar and scent-marking sites, along with nectar availability, influence male movement patterns. We manipulated the distribution of feeders (artificial flowers) and scent-marking locations (branches), and varied nectar delivery rates, to assess effects on foraging, scent-marking, and patrolling. Males responded strongly to spatial structure: in clumped arrays with evenly spaced resources, movements between consecutive visits were shorter and more localised, while in dispersed arrays with irregular spacing, transitions were longer and more variable. The combination of dispersed spacing and low nectar availability imposed the highest foraging demands, resulting in fewer feeding events and reduced total feeding time. Despite these increased costs, males maintained consistent investment in reproductive behaviours, suggesting a prioritisation of mate-seeking over energy gain. Rather than reducing signalling, males adjusted their foraging strategy--favouring fewer but prolonged feeding bouts when nectar availability allowed. These findings reveal a unidirectional behavioural adjustment, in which foraging is modulated to sustain reproductive effort, and show how spatial resource structure and nectar availability together shape movement decisions in male pollinators. LAY SUMMARYMale bumblebees keep searching for mates even when food is scarce, adjusting how they forage to conserve energy. Using 3D tracking in a controlled environment, we found that males reduce foraging effort but maintain reproductive behaviours. This shows how animals balance survival and reproduction in changing environments, offering new insights into pollinator behaviour and resilience.

animal behavior and cognition↗

bioRxiv2025

The influence of bee movements on patterns of pollen transfer between plants: an exploratory model

Most -if not all- pollinators make foraging decisions based on learning and memory. In interaction with environmental conditions and competitive pressure, pollinators cognition shapes their movement patterns, which in turn determine pollen transfers. However, models of animal-mediated pollination often make simplifying assumptions about pollinator movements, notably by not incorporating learning and memory. Better considering cognition as a driver of pollinators movements may thus provide a powerful mechanistic understanding of pollen dispersal. In this exploratory study, we connect pollinator behaviour and plant reproduction by using an agent-based model of bee movements implementing reinforcement learning. Simulations of two bees foraging together in environments containing twenty flowers shows how learning can improve foraging efficiency as well as plant pollination quality through larger mating distances and smaller self-pollination rates, while creating spatially heterogeneous pollen flows. This suggests that pollinators informed foraging decisions contribute to genetic differentiation between plant subpopulations. We believe this theoretical exploration will pave the way for a more systematic analysis of animal-mediated plant mating patterns, as model predictions can be tested experimentally in real bee-plant systems.

animal behavior and cognition↗

bioRxiv2024

Trapline foraging by nectar-collecting hornets

Central place foraging bees, butterflies, birds and bats are known to develop routes in order to visit familiar plant resources in a stable and repeatable order called "traplines". Here we report a similar behaviour in a social wasp, the Japanese yellow hornet Vespa simillima. We monitored the foraging movements of individually marked wild hornets collecting sucrose solution on four artificial flowers placed in the field. After thirty foraging bouts, all the hornets had developed a repeatable flower visitation sequence. Using two different arrays of flowers, we show how hornets increase their foraging efficiency through time but do not always use the shortest path to visit all flowers, often favoring movements between nearest neighbor flowers over global path optimization. Our study adds nectar-foraging wasps to the growing list of animals developing traplines thereby opening new perspectives for comparative cognition research.

animal behavior and cognition↗

bioRxiv2024

Interindividual variability in flower pickiness by foraging bumblebees

Pollinators navigate complex and heterogeneous "flower markets", where floral resources vary in quality, availability, and spatial distribution. Bumblebees, as generalist foragers, visit numerous flowers during their foraging bouts, yet the factors influencing their flower choices and the individual differences in foraging behaviour remain poorly understood. Here, we tested how bees adjust their foraging in response to different reward structures. Bombus terrestris workers completed three foraging bouts in two artificial flower environments: one simulating a favourable environment with patches alternating high- and low-quality flowers (40% vs. 20% w/w sucrose solution), and the other a challenging environment with high-quality flowers alongside unrewarded ones (40% w/w sucrose solution vs. plain water). We hypothesised that bees would improve their foraging efficiency in both environments, but more rapidly in the more extreme one, where the greater reward difference creates stronger pressure to learn quickly. In both conditions, bees increased their sucrose intake per unit time over bouts. We also observed consistent differences in flower selectivity among individuals: in the favourable environment, bees that first visited high-quality flowers focused on them and avoided low-quality ones (became "picky"), while bees that first visited low-quality flowers kept visiting both types. Despite these differences, bees across environments and pickiness levels all reached similar sucrose intake rates by the third foraging bout, either by becoming more selective, collecting more sucrose solution, or reducing time spent foraging. These findings highlight the adaptability of bee foraging and suggest that early flower experiences may contribute to lasting individual differences in foraging behaviour. Significance statementBumblebees are highly efficient pollinators of wild plants and commercial crops, yet their foraging behaviour varies notably among individuals. Understanding why bees differ in their foraging decisions is crucial, as it affects how they collect resources. We show that individual Bombus terrestris workers rapidly adapt to flower patches with different reward qualities. Remarkably, a bees first flower visits have lasting effects: individuals that started with high-quality flowers consistently favoured them and avoided low-quality ones, while those that started with low-quality flowers continued to visit both types over time. Despite these differences, bees reached similar nectar intake rates after just three foraging trips, regardless of how selective they were. Our findings show that bees can quickly adjust their foraging behaviour, and that early experiences play a key role in how they exploit resources across different environments.

animal behavior and cognition↗

bioRxiv2024

Invasive Vespa velutina nigrithorax hornets are more susceptible to entomopathogenic fungus than two other hymenopteran species, the wasp Vespa vulgaris and the bumblebee Bombus terrestris.

Entomopathogenic fungi are commonly used as biological control agents. Recently, a strain of Metarhizium robertsii (Sorokin, 1883) (Hypocreales: Clavicipitaceae) collected in France was identified as a good candidate for controlling invasive populations of yellow-legged hornet, Vespa velutina nigrithorax (Buysson, 1905) (Hymenoptera: Vespidae) in Europe. Since M. robertsii is generalist, its use as bioagent could be damaging for non-targeted species. Here, we compared the lethal effects of three concentrations of this M. robertsii strain on the invasive hornet and two non-targeted species commonly found in Europe, the common wasp Vespa vulgaris (Linnaeus, 1758) (Hymenoptera: Vespidae) and the buff-tailed bumblebee Bombus terrestris (Linnaeus, 1758) (Hymenoptera: Apidae). Exposure to M. robertsii spores altered the survival of all three species but at different degrees. Hornets had consistently lower survival, even under low concentrations of spores, when compared to wasps and bumblebees. Such lower susceptibility of beneficial Hymenoptera is encouraging in the perspectives of using M. robertsii as biocontrol agent against invasive hornets.

animal behavior and cognition↗

bioRxiv2024

Bumblebees increase their learning flight altitude in dense environments

Bumblebees rely on visual memories acquired during the first outbound flights to relocate their nest. While these learning flights have been extensively studied in sparse environments with few objects, little is known about how bees adapt their flight in more dense, cluttered, settings that better mimic their natural habitats. Here we investigated how environmental complexity influences the first outbound flights of bumblebees. In a large arena we tracked the bees 3D positions to examine the flight patterns, body orientations, and nest fixations across environmental conditions characterised by different object constellations around the nest entrance. In cluttered environments, bees prioritised altitude gain over horizontal distance, suggesting a strategy to overcome obstacles and visual clutter. Body orientation patterns became more diverse in dense environments, indicating a balance between nest-oriented learning and obstacle avoidance. Notably, bees consistently preferred to fixate the location of the nest entrance from elevated positions above the dense environment across all conditions. Our results reveal significant changes in the 3D flight structure, body orientations, and nest fixation behaviours as object density increases. This highlights the importance of considering 3D space and environmental complexity in understanding insect navigation.

animal behavior and cognition↗

bioRxiv2024

Bumblebees locate goals in 3D with absolute height estimation from ventral optic flow

When foraging, flying animals like bees are often required to change their flight altitude from close to the ground to above the height of the vegetation to reach their nest or a food source. While the mechanisms of navigating towards a goal in two dimensions are well investigated, the explicit use of height as a source for navigation in three dimensions remains mostly unknown. Our study aims to unravel which strategies bumble-bees use for height estimation and whether they rely on global or local cues. We expanded a 2D goal localization paradigm, where a goal location is indicated by cylindrical landmarks, to the third dimension by using spherical landmarks to indicate a feeders position in 3D and examined the search pattern of bumblebees. Additionally, we assessed the ability of bees to estimate the height of a feeder based on local landmarks and global references such as the ground floor. The search distribution for a feeders position in 3D was less spatially concentrated compared to in 2D. Assessing the bees height estimation ability, we found that bees could estimate a feeders height using the ground floor as a reference. However, the feeder needed to be sufficiently close to the ground floor for the bees to choose correctly. When bumblebees are faced with the challenge of foraging in a 3D environment where the height of a food source and landmark cues are important, they demonstrate the ability to learn and return to a specific flower height. This suggests they rely on ventral optic flow for goal height estimation in bumblebees.

animal behavior and cognition↗

bioRxiv2023

Switching perspective: Comparing ground-level and bird's-eye views for bees navigating clutter

Animals navigating in three dimensions encounter different perspectives of their world, often transitioning from birds eye views at higher altitudes to ground views closer to the ground. How they integrate this information to pinpoint a goal location is virtually unknown. Here we tested the ability of bumblebees to use both types of views when homing in a dense environment in the vicinity of their inconspicuous nest entrance. Our combined modelling and experimental approach examined various views for localising a goal in dense settings. Whereas, birds-eye views performed best in simulations of current nest-centered snapshot homing models, behavioural experiments revealed that bumblebees predominantly relied on ground views when pinpointing nest entrances in dense environments. These findings reveal the limitations of snapshot-homing models and suggest that bumblebees use a combination of navigational tools to successfully find their way home in dense environments. This is not only relevant for understanding bee navigation, but also for other animals and humans navigating in 3D as well as the development of technologies inspired by natural systems, such as autonomous flying robots.

animal behavior and cognition↗

bioRxiv2023

Variation in hemolymph content and properties among three Mediterranean bee species

Hemolymph, as mediator of immune responses and nutrient circulation, can be used as physiological marker of an insects health, environmental quality or ecological adaptations. Recent studies reported intraspecific variation in protein contents and biological activities of the hemolymph of honey bees related to their diet. Here we measured interspecific variation in three common bee species in the Mediterranean Basin with contrasting ecologies: Apis mellifera, Chalicodoma siculum, and Xylocopa pubescens. Despite all the bees were collected in the same area, we found important quantitative and qualitative variations of hemolymph extracts across species. Samples of A. mellifera and C. siculum had much higher protein concentration, anticancer, antimicrobial and antoxidant activities than samples of X. pubescens. This first descriptive study suggests life history traits of bee species have strong influences on their hemolymph properties and call for future large scale comparative analyses across more species and geographical areas.

ecology↗

bioRxiv2023

Intraspecific proteomic profiling and potential biological activities of the honey bee hemolymph

Pollinator declines have raised major concerns for the maintenance of biodiversity and food security, calling for a better understanding of environmental factors that affect their health. Here we used hemolymph analysis, a cheap, simple, yet powerful approach, to monitor the health state of Western honey bees Apis mellifera. We evaluated the intraspecific proteomic variations and the biological activities of hemolymph of bees collected from four Egyptian localities characterized by different food diversities and abundances. Lowest protein concentrations and the weakest bioactivities were recorded in hemolymph of bees artificially fed sucrose solution and no pollen. By contrast, highest protein concentrations and activities were recorded in bees that had the opportunity to feed on various natural resources. While future studies should expand comparisons to honey bee populations exposed to more different diets, our results strongly suggest hemolymph samples can be used as reliable indicators of bee nutrition and health.

physiology↗

bioRxiv2023

Flexible visual learning and memory in nectar foraging hornets

Pollinators, such as bees, develop flexible memories of colours, patterns and shapes, for efficient flower recognition. Here we tested whether other insects facing the same foraging problem have evolved similar cognitive abilities for flexible learning. We trained wild hornets from two species commonly found in Europe (Vespa velutina nigrithorax and Vespa crabro) to associate sucrose solution rewards to colour stimuli in a Y maze. Hornets of both species succeeded in differential and reversal learning, and developed short and long-term memories of the learnt associations. Thus, just like bees, hornet foragers can learn various visual cue-reward associations and remember them over several hours or days for selecting flowers. Our study in non-model species illustrates how standard conditioning approaches can be used to explore and compare the cognitive abilities of animals with similar foraging ecology.

animal behavior and cognition↗

bioRxiv2022

Natural variability in bee brain size and symmetry revealed by micro-CT imaging and deep learning

Analysing large numbers of brain samples can reveal minor, but statistically and biologically relevant variations in brain morphology that provide critical insights into animal behaviour, ecology and evolution. So far, however, such analyses have required extensive manual effort, which considerably limits the scope for comparative research. Here we used micro-CT imaging and deep learning to perform automated analyses of 3D image data from 187 honey bee and bumblebee brains. We revealed strong inter-individual variations in total brain size that are consistent across colonies and species, and may underpin behavioural variability central to complex social organisations. In addition, the bumblebee dataset showed a significant level of lateralization in optic and antennal lobes, providing a potential explanation for reported variations in visual and olfactory learning. Our fast, robust and user-friendly approach holds considerable promises for carrying out large-scale quantitative neuroanatomical comparisons across a wider range of animals. Ultimately, this will help address fundamental unresolved questions related to the evolution of animal brains and cognition. Author SummaryBees, despite their small brains, possess a rich behavioural repertoire and show significant variations among individuals. In social bees this variability is key to the division of labour that maintains their complex social organizations, and has been linked to the maturation of specific brain areas as a result of development and foraging experience. This makes bees an ideal model for understanding insect cognitive functions and the neural mechanisms that underlie them. However, due to the scarcity of comparative data, the relationship between brain neuro-architecture and behavioural variance remains unclear. To address this problem, we developed an AI-based approach for automated analysis of brain images and analysed an unprecedentedly large dataset of honey bee and bumblebee brains. Through this process, we were able to identify previously undescribed anatomical features that correlate with known behaviours, supporting recent evidence of lateralized behaviour in foraging and pollination. Our method is open-source, easily accessible online, user-friendly, fast, accurate, and robust to different species, enabling large-scale comparative analyses across the animal kingdom. This includes investigating the impact of external stressors such as environmental pollution and climate change on cognitive development, helping us understand the mechanisms underlying the cognitive abilities of animals and the implications for their survival and adaptation.

animal behavior and cognition↗

bioRxiv2022

Modeling bee movement shows how a perceptual masking effect can influence flower discovery, foraging efficiency and pollination

Understanding how pollinators move across space is key to understanding plant mating patterns. Bees are typically assumed to search for flowers randomly or using simple movement rules, so that the probability of discovering a flower should primarily depend on its distance to the nest. However, experimental work shows this is not always the case. Here, we explored the influence of flower size and density on their probability of being discovered by bees by developing a movement model of central place foraging bees, based on experimental data collected on bumblebees. Our model produces realistic bee trajectories by taking into account the autocorrelation of the bees angular speed, the attraction to the nest, and a gaussian noise. Simulations revealed a << masking effect >> that reduces the detection of flowers close to another, which may have critical consequences for pollination and foraging success. At the plant level, flowers distant to the nest were more often visited in low density environments, suggesting lower probabilities of pollination at high densities. At the bee colony level, foragers found more flowers when they were small and at medium densities, suggesting that there is an optimal flower size and density at which collective foraging efficiency is optimized. Our results indicate that the processes of search and discovery of resources are potentially more complex than usually assumed, and question the importance of resource distribution and abundance on plant-pollinator interactions. Authors summaryUnderstanding how pollinators move in space is key to understanding plant reproduction, which in turn shapes entire ecosystems. Most current models assume simple movement rules that predict that flowers are more likely to be visited--and hence pollinated--the closer they are to the pollinators nest. Here we developed an explicit movement model that incorporates realistic features of bumblebees, including their flight characteristics and their tendency to return regularly to the nest, and calibrated it with experimental data collected in naturalistic conditions. This model revealed that the probability to visit a flower does not only depend on its position, but also on the position of other flowers that may mask it from the forager. This masking effect means that pollination efficiency depends on the density and spatial arrangement of flowers around the pollinators nest, often in counter-intuitive ways. Taking these effects into account will be key for improving precision pollination and pollinator conservation.

animal behavior and cognition↗

bioRxiv2022

Supplementation in vitamin B3 counteracts the negative effects of tryptophan deficiencies in bumble bees

Increasing evidence highlights the importance of diet content in 9 essential amino acids for bee physiological and behavioral performance. However, the tenth essential amino acid, tryptophan, has been overlooked as its experimental measurement requires a specific hydrolysis. Tryptophan is the precursor of serotonin and vitamin B3, which together modulate cognitive and metabolic functions in most animals. Here, we investigated how tryptophan deficiencies influence the longevity and behavior of bumble bees. Tryptophan-deficient diets led to a moderate increase in food intake, aggressiveness and mortality compared to the control diet. Vitamin B3 supplementation in tryptophan-deficient diets tended to buffer these effects on food intake and survival, and significantly reduced workers aggressiveness. Considering that the pollens of major crops and common plants, such as corn and dandelion, are deficient in tryptophan, these effects could have a strong impact on bee populations and their pollination service.

physiology↗