Biology subjects

Grueter, C.

Publications and source records attributed to Grueter, C..

12 recordsLinked to original sources

bioRxiv2025

Comprehensive Analysis of RFID Performance of the iID BEEscience system

Radio Frequency Identification (RFID) technology has been widely used to study the activity and behaviour of various organisms, including bees. In this study, we rigorously evaluate the performance of a recently developed RFID system (iID(R)BEEscience from MicroSensys) in tracking bees under different conditions. We assessed the systems accuracy in detecting and identifying travel direction both in controlled laboratory settings and with free-flying bees. Additionally, we analysed the sources of incorrect or redundant readings and provide a Python script designed to filter out erroneous data, summarising the results in biologically relevant measurements (foraging trip number, trip duration, instances of drifting). Our controlled laboratory tests revealed that the RFID systems accuracy ranged from 93% to 100% in most cases, though accuracy diminished when a large number of transponders passed through the reader simultaneously. We also found certain transponder positions in relation to the reader position to be less reliable. In field conditions, we tracked 33 foraging trips of RFID-tagged honeybees trained to a sucrose solution feeder and observed a 100% success rate in identifying all foraging trips via the RFID data. Given that the transponders weigh only 2.1 mg, we propose that this system is a reliable tool for studying smaller bees (and other insects), which are currently understudied using RFID technology, although its application to species smaller than honeybees (Apis mellifera) requires further testing. This research demonstrates the potential of RFID technology for advancing the study of insect behaviour under field conditions beyond traditional models like honeybees or bumblebees.

animal behavior and cognition↗

bioRxiv2024

Social learning of navigational routes in tandem running acorn ants (Temnothorax nylanderi)

Tandem running in ants is a form of social learning that involves an informed leader guiding a naive nestmate to a valuable resource, such as a nest site or a food source. Little is currently known about what tandem followers learn and how socially acquired navigational information affects future trips. While some studies suggest that tandem followers learn the resource position but not the route taken by the tandem pair to reach the resource, more recent evidence contradicts this view. We studied tandem running in foraging acorn ants Temnothorax nylanderi and provide evidence that tandem followers socially learn routes from their leaders and later use these routes when travelling between their nest and a food source. Followers that became tandem leaders themselves then guided their follower along the same routes in 90% of tandem runs, demonstrating that navigational information can spread in a forager population through sequential social learning. Ants increased their travelling speed, but not path straightness over successive trips. We also found that ants needed less time on subsequent trips if they experienced longer-lasting tandem runs, suggesting that longer lasting tandem runs allow followers to learn routes more efficiently. Adding visual cues did not affect most of the quantified variables, and we currently know little about the cues used by T. nylanderi during navigation. We discuss how the visual environment inhabited by different species might affect the importance of route learning during tandem running.

animal behavior and cognition↗

bioRxiv2023

Extensive loss of forage diversity in social bees due to flower constancy and communication in simulated environments

Bees require a diverse diet for a healthy development. Many bee species show flower constancy, that is, they visit flowers of just one species during a foraging trip. Flower constancy is important for plant reproduction, but it could impair dietary diversity in bees, especially in biodiversity-depleted, human-modified landscapes. It is assumed that flower constancy does not lower dietary diversity in social bees, such as honey bees or bumble bees, because different colony members can specialise on different plant species. However, this has never been tested. We used computer simulations to investigate the effects of flower constancy on colony diet in plant species-rich and species-poor landscapes. We also explored if communication about food sources, which is used in many social bees, further reduces forage diversity. Our simulations reveal an extensive loss of forage diversity due to flower constancy in both plant species-rich and species-poor environments. Small colonies often discovered only 30-50% of all available plant species, thereby increasing the risk of nutritional deficiencies. Our simulation results could explain why bumble bees, which have small colony sizes, are less flower constant than honey bees and stingless bees, which have larger colony sizes. Remarkably, when colonies also communicated about food sources, Simpsons diversity, which measures the evenness of flower visits, approached near zero in plant species-poor environments. Finally, we found that food source clustering, but not habitat fragmentation impaired dietary diversity. These findings can help in the design of landscapes that increase forage diversity and improve bee nutrition and health in human-modified landscapes.

ecology↗

bioRxiv2022

OPA1 Downregulation in Skeletal Muscle Induces MERC formation in an ATF4-Dependent Manner

Mitochondria and endoplasmic reticulum (ER) contact sites (MERCs) are protein- and lipid-enriched hubs that mediate interorganellar communication by contributing to the dynamic transfer of Ca2+, lipid, and other metabolites between these organelles. Defective MERCs are associated with cellular oxidative stress, neurodegenerative disease, and cardiac and skeletal muscle pathology via mechanisms that are poorly understood. We previously demonstrated that skeletal muscle-specific knockdown (KD) of the mitochondrial fusion mediator optic atrophy 1 (OPA1) induced ER stress and correlated with an induction of Mitofusin-2, a known MERC protein. In the present study, we tested the hypothesis that Opa1 downregulation in skeletal muscle cells alters MERC formation by evaluating multiple myocyte systems, including from mice and Drosophila, and in primary myotubes. Our results revealed that OPA1 deficiency induced tighter and more frequent MERCs in concert with a greater abundance of MERC proteins involved in calcium exchange. Additionally, loss of OPA1 increased the expression of activating transcription factor 4 (ATF4), an integrated stress response (ISR) pathway effector. Reducing Atf4 expression prevented the OPA1-loss-induced tightening of MERC structures. OPA1 reduction was associated with decreased mitochondrial and sarcoplasmic reticulum, a specialized form of ER, calcium, which was reversed following ATF4 repression. These data suggest that mitochondrial stress, induced by OPA1 deficiency, regulates skeletal muscle MERC formation in an ATF4-dependent manner.

biophysics↗

bioRxiv2022

Early Life Exposure to Queen Mandibular Pheromone Mediates Persistent Transcriptional Changes in the Brain of Honey bee Foragers

How behavior in insect societies is regulated remains a fundamental question in sociobiology. In hymenopteran societies, the queen plays a crucial role in regulating group behavior by affecting individual behavior, physiology, and lifespan through worker gene expression. Honey bee (Apis mellifera) queens signal their presence via the queen mandibular pheromone (QMP). While QMP has been shown to influence the behavior of young workers, we know little about its long-term molecular impacts on workers and whether these pheromone effects depend on an early sensitive period in the life of a worker. Here we demonstrate that QMP treatment strongly impacts long-term forager gene expression in the mushroom bodies, antennal lobes, and antennae, but only if bees were treated early in life (1-2 days of age). Contrary to our expectation, foraging activity was not impacted by QMP treatment in the long-term, but genes important for division of labor, learning, chemosensory perception and aging were differentially expressed in the antennae and brain tissues, suggesting that QMP influences diverse physiological and behavioral processes in workers. Overall, our study suggests a sensitive period early in the life of workers, where the queens presence or absence has strong and potentially livelong effects on transcriptional activity in the central and peripheral nervous system. Significance statementDespite our increasing understanding of how social cues affect gene expression and behavior in social animals, we still know little about the importance of sensitive periods in cue perception for the long-term regulation of gene expression. Honey bees live in complex societies and queen pheromones play a central role in the regulation of worker behavior and division of labor. We tested the exposure to queen pheromone presence and found that there is a sensitive period in the early adult life of workers. Understanding and identifying sensitive periods and their effect on long-term gene transcription in workers in response to changes in the environment will lay an important foundation for a better understanding of how queens shape colony life.

animal behavior and cognition↗

bioRxiv2022

Social and individual learners use different pathways to success in an ant mini-society

Animals can acquire information through individual learning or by copying others. Simulations suggest that social learning is expected to lead to better rewards, but experimental studies confirming this remain scarce. We tested how a well-known form of social learning in ants, tandem running, affects individual foraging success of Temnothroax nylanderi foragers in controlled laboratory experiments. We manipulated the number and the variability of food sources and assessed the foraging choices of ants searching individually (i.e. scouts) or using social learning (i.e. recruits). We found that social learners indeed discovered better food sources than individual learners, but only in rich environments. However, social learners collected less food ([~]60% fewer foraging trips) than scouts during our trials. Interestingly, individual learners improved their success over time by switching food sources more frequently than social learners. These experimental findings highlight that the relative value of social and individual learning in an ant society depend on the foraging environment and show different temporal dynamics. The ability of individual learners to exploit profitable food sources through a strategy of food source switching, while avoiding the opportunity costs of social learning can help explain why many social insects, especially those living in small colonies, do not use communication in foraging.

animal behavior and cognition↗

bioRxiv2022

When should bees be flower constant? An agent-based model highlights the importance of social information and foraging conditions

O_LIMany bee species show flower constancy, i.e. a tendency to visit flowers of one type during a foraging trip. Flower constancy is important for plant reproduction, but whether bees also benefit from flower constancy remains unclear. Social bees, which often use communication about food sources, show particularly strong flower constancy. C_LIO_LIWe hypothesised that the sharing of social information increases the benefits of flower constancy because foragers share information selectively about high-quality food sources, thereby reducing the need to sample alternatives. We also asked if foraging landscapes affect flower constancy. We developed an agent-based model that allowed us to simulate bee colonies with and without communication and flower constancy in different foraging environments. C_LIO_LIFlower constancy alone performed poorly in all environments, while indiscriminate flower choice was often the most successful strategy. However, communication improved the performance of flower constant colonies in nearly all tested environments. This combination was particularly successful when high-quality food sources were abundant and competition was weak. C_LIO_LIOur findings help explain why social bees tend to be more flower constant than solitary bees and suggest that flower constancy can be an adaptive strategy in social bees. Simulations suggest that anthropogenic changes of foraging landscapes will have different effects on the foraging performance of bees that vary in flower constancy. C_LI

animal behavior and cognition↗

bioRxiv2022

Ancestral state reconstruction suggests repeated losses of recruitment communication during ant evolution (Hymenoptera: Formicidae)

Eusocial insects have evolved different strategies to share information about their environment and workers can recruit nestmates to food sources or new nest sites. Ants are the most species-rich social insect group and are known to use pheromones, visual and tactile signals to communicate and inform nestmates about resources. However, how these different strategies evolved and whether there was a predominant evolutionary sequence that led to present day recruitment strategies is not well understood. In our study we explored two competing hypotheses about the ancestral recruitment communication: (1) ant ancestors did not recruit nestmates and species evolved more complex recruitment strategies over time vs. (2) early ants used mass-recruitment, which was lost repeatedly in some lineages. We combined an extensive search of the scientific literature and ancestral state reconstruction to estimate the ancestral recruitment strategy, focusing on the categories (i) no recruitment, (ii) tandem running, (iii) group-recruitment and (iv) chemical mass-recruitment. Stochastic character mapping suggests that mass-recruitment was ancestral in ants (59-61%), whereas "no recruitment" was unlikely to be the ancestral condition (21%). Similarly, marginal ancestral state reconstruction suggests that mass-recruitment (44-81%) or group-recruitment (48-50%) represented the original state. Our results are consistent with the finding that early ants lived in colonies containing up to several thousand individuals, which are typically associated with mass-recruiting in ants. However, our ability to robustly identify patterns in the evolution of communication in ants remains hampered by a lack of natural history information for most ant species.

animal behavior and cognition↗

bioRxiv2020

Use of waggle dance information in honey bees is linked to gene expression in the antennae, but not in the brain

Communication is essential for social animals, but deciding how to utilize information provided by conspecifics is a complex process that depends on environmental and intrinsic factors. Honey bees use a unique form of communication, the waggle dance, to inform nestmates about the location of food sources. However, as in many other animals, experienced individuals often ignore this social information and prefer to rely on prior experiences, i.e. private information. The neurosensory factors that drive the decision to use social information are not yet understood. Here we test whether the decision to use social dance information or private information is linked to gene expression differences in different parts of the nervous system. We trained bees to collect food from sugar water feeders and observed whether they utilize social or private information when exposed to dances for a new food source. We performed transcriptome analysis of four brain parts critical for cognition: the subesophageal ganglion, the central brain, the mushroom bodies, and the antennal lobes but, unexpectedly, detected no differences between social or private information users. In contrast, we found 413 differentially expressed genes in the antennae, suggesting that variation in sensory perception mediate the decision to use social information. Social information users were characterized by the upregulation of dopamine and serotonin genes while private information users upregualted several genes coding for odor perception. These results highlight that decision making in honey bees might also depend on peripheral processes of perception rather than higher-order brain centers of information integration.

animal behavior and cognition↗

bioRxiv2020

Automatic Analysis of Bees' Waggle Dance

This work describe an algorithm for the automatic analysis of the waggle dance of honeybees. The algorithm analyses a video of a beehive with 13,624 frames, acquired at 25 frames/second. The algorithm employs the following traditional image processing steps: conversion to grayscale, low pass filtering, background subtraction, thresholding, tracking and clustering to detect run of bees that perform waggle dances. The algorithm detected 44,530 waggle events, i.e. one bee waggling in one time frame, which were then clustered into 511 waggle runs. Most of these were concentrated in one section of the hive. The accuracy of the tracking was 90% and a series of metrics like intra-dance variation in angle and duration were found to be consistent with literature. Whilst this algorithm was tested on a single video, the ideas and steps, which are simple as compared with Machine and Deep Learning techniques, should be attractive for researchers in this field who are not specialists in more complex techniques.

animal behavior and cognition↗

bioRxiv2020

The adaptive value of tandem communication in ants: insights from an agent-based model

Social animals often share information about the location of resources, such as a food source or a new nest-site. One well-studied communication strategy in ants is tandem running, whereby a leader guides a recruit to a resource. Tandem running is considered an example of animal teaching because a leader adjusts her behaviour and invests time to help another ant to learn the location of a resource more efficiently. Tandem running also has costs, such as waiting inside the nest for a leader and a reduced walking speed. Whether and when these costs outweigh the benefits of tandem running is not well understood. We developed an agent-based simulation model to investigate the conditions that favour communication by tandem running during foraging. We predicted that the spatio-temporal distribution of food sources, colony size and the ratio of scouts and recruits affect colony foraging success. Our results suggest that communication is favoured when food sources are hard to find, of variable quality and long lasting. These results mirror the findings of simulations of honeybee communication. Scouts locate food sources faster than tandem followers in some environments, suggesting that tandem running may fulfil the criteria of teaching only in some situations. Furthermore, tandem running was only beneficial above a critical colony size threshold. Taken together, our model suggests that there is a considerable parameter range that favours colonies that do not use communication, which could explain why many social insects with small colony sizes forage solitarily.

animal behavior and cognition↗

bioRxiv2019

Large body size variation is linked to low communication success in tandem running ants

Diversity in animal groups is often assumed to increase group performance. In insect colonies, genetic, behavioral and morphological variation among workers can improve colony functioning and resilience. However, it has been hypothesized that during communication processes, differences between workers, e.g. in body size, could also have negative effects. Tandem running is a common recruitment strategy in ants and allows a leader to guide a nestmate follower to resources. A substantial proportion of tandem runs fail because leader and follower loose contact. Using the ant Temnothorax nylanderi as a model system, we tested the hypothesis that tandem running success is impaired if leader and follower differ in size. Indeed, we found that the success rate of tandem pairs drops considerably as size variation increases: only ~7% of tandem runs were successful when the leader-follower size difference exceeded 10%, whereas 80% of tandem runs were successful when ants differed less than 5% in body length. One possible explanation is that ant size is linked to the preferred walking speed. Ants did not choose partners of similar size, but extranidal workers were larger than intranidal workers, which could reduce recruitment mistakes because it reduced the chance that very large and very small ants perform tandem runs together. Our results suggest that phenotypic differences between interacting workers can have negative effects on the efficiency of communication processes. Whether phenotypic variation has positive or negative effects is likely to depend on the task and the phenotypic trait that shows variation.

animal behavior and cognition↗