Dynamic workforce modulation and foraging efficiency in Eusocial insect colonies
4 affiliations
- 1Grup de Física Estadística, Departament de Física. Facultat de Ciències, Universitat Autònoma de Barcelona, Bellaterra (Barcelona), Spain
- 2Centre d’Estudis Avançats de Blanes (CEAB-CSIC), Blanes, Girona, Spain
- 3ICREA, Institut Català de Recerca i Estudis Avançats, Barcelona, Spain
- 4Centre de Recerca Ecològica i Aplicacions Forestals (CREAF), Cerdanyola del Vallès, Barcelona, Spain
Abstract
Understanding the fitness advantages conferred by eusociality remains a central challenge in behavioral ecology. One promising approach is to identify collective strategies that shift efficiency within social groups. Here, we explore the hypothesis that reserve workforces in ant colonies represent an adaptive mechanism that enhances flexibility and foraging efficiency under fluctuating environmental conditions. We examine how departure and return rates of foragers modulate such reserve workers and how these time-dependent dynamics shape the colony’s overall energetic balance. By integrating an energetic-balance framework with stochastic search simulations inspired by empirical results from four colonies of Aphaenogaster senilis ants, we quantify the energetic requirements for colony viability, incorporating energy intake, search costs, and basal metabolic demands. Our results show that as colonies grow, maintaining a positive energy balance requires a disproportionately larger relative workforce. By modulating departure and return rates over time, colonies control the synchrony of their collective search and efficiently activate or suppress their reserve workforce to scale foraging effort as needed. These findings suggest that the “lazy” or weakly engaged workers commonly observed in large colonies function as an essential reserve that stabilizes colony energetics and enhances responsiveness. Together, our results provide a functional explanation for sublinear metabolic scaling in eusocial groups and highlight workforce modulation as a key factor underlying their energetic stability and evolutionary success. Author summary: Understanding how social insect colonies balance energy expenditure with resource acquisition is central to explaining their ecological success. Here, we develop a theoretical framework that links (i) energetic constraints necessary to reach a positive energy balance in the colony, to (ii) the proportion of workers actively engaged in foraging. Our results analyze the fundamental trade-off between increasing the number of active foragers to improve resource discovery, and the corresponding increase in the metabolic costs. As colonies grow, the latter becomes increasingly important, so strategies for regulating the fraction of workers actively engaged in foraging becomes critical. As a solution to this, large colonies would benefit from maintaining a reserve of inactive workers that can be recruited whenever necessary. This provides a functional explanation for the widespread presence of apparently “lazy” individuals in eusocial societies, suggesting that they contribute to colony resilience rather than representing inefficiency. The model predicts how environmental conditions influence colony size and search strategies, and offers testable hypotheses linking task allocation, metabolic scaling, and collective behaviour. More broadly, our findings highlight workforce redundancy as a mechanism supporting the energetic stability and evolutionary success of complex social systems.
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BibTeX
@article{campos2026dynamic,
title = {{Dynamic workforce modulation and foraging efficiency in Eusocial insect colonies}},
author = {Daniel Campos and Javier Cristín and Pol Fernández-López and Roger Lloret-Cabot and Meritxell Genovart and Frederic Bartumeus},
journal = {PLOS Computational Biology},
year = {2026},
month = oct,
doi = {10.1371/journal.pcbi.1014258},
url = {https://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1014258},
note = {CC BY},
}
RIS
TY - JOUR
TI - Dynamic workforce modulation and foraging efficiency in Eusocial insect colonies
AU - Daniel Campos
AU - Javier Cristín
AU - Pol Fernández-López
AU - Roger Lloret-Cabot
AU - Meritxell Genovart
AU - Frederic Bartumeus
PY - 2026
DA - 2026/10/01
JO - PLOS Computational Biology
DO - 10.1371/journal.pcbi.1014258
UR - https://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1014258
AB - Understanding the fitness advantages conferred by eusociality remains a central challenge in behavioral ecology. One promising approach is to identify collective strategies that shift efficiency within social groups. Here, we explore the hypothesis that reserve workforces in ant colonies represent an adaptive mechanism that enhances flexibility and foraging efficiency under fluctuating environmental conditions. We examine how departure and return rates of foragers modulate such reserve workers and how these time-dependent dynamics shape the colony’s overall energetic balance. By integrating an energetic-balance framework with stochastic search simulations inspired by empirical results from four colonies of Aphaenogaster senilis ants, we quantify the energetic requirements for colony viability, incorporating energy intake, search costs, and basal metabolic demands. Our results show that as colonies grow, maintaining a positive energy balance requires a disproportionately larger relative workforce. By modulating departure and return rates over time, colonies control the synchrony of their collective search and efficiently activate or suppress their reserve workforce to scale foraging effort as needed. These findings suggest that the “lazy” or weakly engaged workers commonly observed in large colonies function as an essential reserve that stabilizes colony energetics and enhances responsiveness. Together, our results provide a functional explanation for sublinear metabolic scaling in eusocial groups and highlight workforce modulation as a key factor underlying their energetic stability and evolutionary success. Author summary: Understanding how social insect colonies balance energy expenditure with resource acquisition is central to explaining their ecological success. Here, we develop a theoretical framework that links (i) energetic constraints necessary to reach a positive energy balance in the colony, to (ii) the proportion of workers actively engaged in foraging. Our results analyze the fundamental trade-off between increasing the number of active foragers to improve resource discovery, and the corresponding increase in the metabolic costs. As colonies grow, the latter becomes increasingly important, so strategies for regulating the fraction of workers actively engaged in foraging becomes critical. As a solution to this, large colonies would benefit from maintaining a reserve of inactive workers that can be recruited whenever necessary. This provides a functional explanation for the widespread presence of apparently “lazy” individuals in eusocial societies, suggesting that they contribute to colony resilience rather than representing inefficiency. The model predicts how environmental conditions influence colony size and search strategies, and offers testable hypotheses linking task allocation, metabolic scaling, and collective behaviour. More broadly, our findings highlight workforce redundancy as a mechanism supporting the energetic stability and evolutionary success of complex social systems.
SN - 1553-7358
SN - 1553-734X
ER -