Biology subjects

Frank, E. T.

Publications and source records attributed to Frank, E. T..

10 recordsLinked to original sources

bioRxiv2026

Feeding Ecology and Behavioral Adaptations Shape Injury Patterns in Central European Ants

Injuries are common in animals and represent a major threat to individual survival. They can result from inter- or intraspecific conflict, predation, or pugnacious prey. Despite their potential ecological and evolutionary importance, injury patterns remain poorly documented in animal populations. To test whether a species feeding ecology or habitat can predict injury patterns, we quantified injury rates and affected body regions among native ant species collected from different habitats in Bavaria, Germany. Specimens were sampled using pitfall traps, which proved to be an efficient method for injury assessment. Injury rates varied substantially among species and genera, ranging from 0% to 38%. Predatory ant species exhibited higher frequencies of leg injuries, whereas omnivorous species were more frequently injured at the antennae. The distribution of injuries likely reflects both foraging ecology and species-specific wound care behaviors, with a high frequency of trochanter injuries potentially indicating prior amputation events to cope with infected leg injuries, as observed in Lasius alienus. Our findings demonstrate that injury propensity and distribution are shaped by feeding habits and behavioral adaptations, providing comparative evidence that the costs and management of injuries vary systematically among ant species. Our study thus highlights injuries as a measurable axis of selection that may have contributed to the emergence of wound care and other forms of social immunity in ants.

ecology↗

bioRxiv2025

Tolerance toward foreigners in ants requires chronic exposure for establishment but only sporadic exposure for maintenance

Social insects discriminate between foreigners and members of their own colony via complex olfactory cues. How plastic this discriminatory behavior is, and whether and under what circumstances ants can learn to accept genetically distinct individuals as nestmates, is poorly understood. Here, we study this question in the clonal raider ant, Ooceraea biroi, which provides unparalleled experimental control over the genotype of individuals and the genotypic composition of colonies. Using a cross-fostering design with mixed-genotype colonies of wild-type and transgenically labelled individuals, we show that ants become non-aggressive specifically toward their foster genotype. This tolerance is transient, and aggression resumes after two weeks of being isolated from the foster colony. However, even sporadic re-exposure to individuals from the foster colony is sufficient to maintain tolerance for over a month, while the same paradigm fails to establish tolerance in the first place. This shows that non-nestmate discrimination is remarkably plastic and that, once established, tolerance toward foreigners can be maintained by only intermittent contact. These dynamics echo general principles of social learning and contact-dependent tolerance described in other social species, including humans.

animal behavior and cognition↗

bioRxiv2025

Social and Spatial Affinity Drive Wound Care by Ants

In group-living animals, open wounds pose a risk not only for the injured individual but also for the entire group, especially when the risk of infection transmission is high. To mitigate this danger, different species have developed diverse strategies - with ants representing one of the few taxa beyond humans that engage in social wound care. Yet, who provides this care and what determines its allocation remains unclear. To answer these questions, we combined controlled injury experiments with automated behavioral tracking across six colonies of the ant Camponotus fellah. Our results reveal that wound care is primarily provided by a non-specialized subset of individuals whose behavioral traits align with a transitional phase between the nurse and forager roles. Among these transitioning ants, care provision was best predicted by their prior spatial and social proximity to the injured individuals in the hours before the injury, indicating that pre-existing social affinity influences caregiving behavior. These findings offer the first empirical evidence of how caregivers are integrated into the colonys social structure and highlight the role of social interactions in shaping the organization of wound care in ants.

animal behavior and cognition↗

bioRxiv2025

Evolution of first aid and social wound care in an army ant society

Injuries and infections pose a significant threat to fitness. Animals cope with this problem by performing self-medication or receiving social care from members of the group. While the benefits of wound care in increasing survival are clear, the forces driving the evolution of these behaviours are not fully understood. Contrary to the current hypothesis that social wound care is more likely to evolve in small groups due to the high relative value of an individual, we demonstrate that group size is not necessary for its evolution or retention. Instead, our theoretical model formalises how injury rate and lethality are fundamental drivers of care rather than group size. This is further evidenced by the presence of wound care in the army ant Eciton burchellii, a species with colonies of [~]1 million ants that hunts pugnacious prey. Here, wound care significantly increased survival in ants with infected wounds, occurring in two phases: direct care at the raiding site, and treatment with antimicrobial secretions in the bivouac. This species is the first to provide on-site care, thereby minimising the latency to receive care and thus potentially the likelihood of lethal wound infection. Our findings reject the notion that small group size is necessary for the evolution or retention of social wound care, revealing instead that injury-driven care can be a widespread and adaptive feature of even the largest insect societies. Significance StatementInjuries and infections threaten survival, but animals can counter these dangers through self-medication or social care. It has been suggested that helping behaviours directed towards vulnerable or injured individuals, such as social wound care, are more likely to evolve in small groups. This study in an army ant with [~]1 million workers shows otherwise, with injury frequency likely being the key component for the evolution or retention of wound-care behaviours. The unique strategy of on-site care at the raiding site, followed by antimicrobial care inside the bivouac, significantly improved survival outcomes. Our theoretical model further shows that even at low rates of care, fitness benefits are high, suggesting that social wound care may be far more widespread than previously thought.

evolutionary biology↗

bioRxiv2025

Better Safe Than Sorry: Leg Amputations as a Prophylactic Wound Care Behaviour in Carpenter Ants

Animals often sustain injuries, which are susceptible to lethal infections. In social insects, wound care behaviours have evolved to reduce these risks. But the limits of wound care behaviours remain unclear. Here we investigated the wound care behaviours of the ant Camponotus maculatus. Our findings show that amputation of legs infected with Pseudomonas aeruginosa significantly reduced mortality. However, nestmates do not differentiate between infected and sterile injuries, providing similar treatments regardless of infection. Even though we show that early amputation correlates with higher survival rates, nestmates amputate indiscriminately on legs with fresh or old wounds. Additionally, cuticular hydrocarbon profiles differed between ants with infected or sterile wounds only 24 hours post-injury, a timepoint when amputations are no longer effective. We propose that C. maculatus workers perform prophylactic amputations regardless of injury state or age. This is in sharp contrast to previous studies which showed clear capabilities to treat infected wounds differently in ants using antimicrobial compounds. This work therefore shows the limits of wound care behaviours in social insects, allowing us to better understand the evolutionary drivers of this unique behaviour.

animal behavior and cognition↗

bioRxiv2023

Gut microbiota influences foraging onset without affecting division of labor and associated physiological hallmarks in honeybees

Gut microbes can impact cognition and behavior, but whether they regulate division of labor in animal societies is unknown. We addressed this question using honeybees since they exhibit division of labor between nurses and foragers and because their gut microbiota can be manipulated. Using automated behavioral tracking and controlling for co-housing effects, we show that gut microbes influence the age at which bees start foraging but have no effects on the time spent in a foraging area and number of foraging trips. Moreover, the gut microbiota did not influence hallmarks of behavioral maturation such as body weight, cuticular hydrocarbon (CHC) profile, hypopharyngeal gland size, and the proportion of bees maturing into foragers. Overall, this study shows that the honeybee gut microbiota does not affect division of labor but rather plays an important function in controlling the onset of bee foraging.

evolutionary biology↗

bioRxiv2023

Behavioural individuality determines infection risk in clonal ant colonies

In social groups, disease risk is not distributed evenly across group members. Individual behaviour is a key source of variation in infection risk, yet its effects are difficult to separate from those of other factors. Here, we combine long-term epidemiological experiments and automated tracking in clonal raider ant colonies, where behavioural individuality emerges among identical workers. We find that: 1) division of labour determines the distribution of parasitic nematodes (Diploscapter) among hosts, showing that differences in infection can emerge from behavioural variation alone, 2) infections affect colony social organisation by causing infected workers to stay in the nest. By disproportionally infecting some workers and shifting their spatial distribution, infections reduce division of labour and increase spatial overlap between hosts, which is expected to facilitate parasite transmission. Thus, division of labour, a defining feature of many societies, not only shapes infection risk and distribution but can also be modified by parasites.

animal behavior and cognition↗

bioRxiv2022

The alarm pheromone and alarm response of the clonal raider ant

Ants communicate via an arsenal of different pheromones produced in a variety of exocrine glands. For example, ants release alarm pheromones in response to danger to alert their nestmates and to trigger behavioral alarm responses. Here we characterize the alarm pheromone and the alarm response of the clonal raider ant Ooceraea biroi, a species that is amenable to laboratory studies but for which no pheromones have been identified. During an alarm response, ants quickly become unsettled, leave their nest pile, and are sometimes initially attracted to the source of alarm, but ultimately move away from it. We find that the alarm pheromone is released from the head of the ant and identify the putative alarm pheromone as a blend of two compounds found in the head, 4-methyl-3-heptanone and 4-methyl-3-heptanol. These compounds are sufficient to induce alarm behavior alone and in combination. They elicit similar, though slightly different behavioral features of the alarm response, with 4-methyl-3-heptanone being immediately repulsive and 4-methyl-3-heptanol being initially attractive before causing ants to move away. The behavioral response to these compounds in combination is dose-dependent, with ants becoming unsettled and attracted to the source of alarm pheromone at low concentrations and repulsed at high concentrations. While 4-methyl-3-heptanone and 4-methyl-3-heptanol are known alarm pheromones in other more distantly related ant species, this is the first report of the chemical identity of a pheromone in O. biroi, and the first alarm pheromone identified in the genus Ooceraea. Identification of a pheromone that triggers a robust, consistent, and conserved behavior, like the alarm pheromone, provides an avenue to dissect the behavioral and neuronal mechanisms underpinning chemical communication.

animal behavior and cognition↗

bioRxiv2022

Infection signaling and antimicrobial wound care in an ant society

Infected wounds pose a major mortality risk in animals1,2. Injuries are common in the ant Megaponera analis, which raids pugnacious prey3,4. Here we show that M. analis can determine when wounds are infected and treat them accordingly. By applying a variety of antimicrobial compounds and proteins secreted from the metapleural gland to infected wounds, workers reduce the mortality of infected individuals by 90%. Chemical analyses showed that wound infection is associated with specific changes in the cuticular hydrocarbon profile, thereby likely allowing nestmates to diagnose the infection state of injured individuals and apply the appropriate antimicrobial treatment. This study demonstrates that the targeted use of antimicrobials to treat infected wounds, previously thought to be a uniquely human behavior, has evolved in insect societies as well.

animal behavior and cognition↗

bioRxiv2022

The gut microbiota affects the social network of honeybees

The gut microbiota influences animal neurophysiology and behavior but has not previously been documented to affect emergent group-level behaviors. Here we combine gut microbiota manipulation with automated behavioral tracking of honeybee sub-colonies to show that the microbiota increases the rate and specialization of social interactions. Microbiota colonization was associated with higher abundances of one third of metabolites detected in the brain, including several amino acids, and a subset of these metabolites were significant predictors of social interactions. Colonization also affected brain transcriptional processes related to amino acid metabolism and epigenetic modification in a brain region involved in sensory perception. These results demonstrate that the gut microbiota modulates the emergent colony social network of honeybees, likely via changes in chromatin accessibility and amino acid biosynthesis.

animal behavior and cognition↗