Ageing in Honeybees: Telomere Length Is Driven by Climate and Resource Availability Rather Than Urbanisation or Pollution.

Understanding how biodiversity responds to human-caused environmental change represents a major scientific challenge. Among the biological processes underlying these responses, ageing plays a critical role by shaping individual life histories and, ultimately, demographic dynamics. Telomeres, the repetitive nucleotide sequences at the ends of linear chromosomes, are widely used biomarkers of ageing, as their length can be shaped by environmental conditions, and can predict health and lifespan. Despite this, few broad-scale ecological studies have examined how telomere length varies in response to environmental change in wildlife. Here, we investigate whether telomeres of a globally widespread pollinator species, the honeybee Apis mellifera, are shaped by gradients of urbanisation, environmental pollution, climatic conditions, and floral resources in central Argentina. To that end, we sampled 981 individuals across 9 localities and 57 sites spanning a ~1000 km gradient of environmental variation. Urbanisation (β = 0.032, 95% CI [-0.048, 0.112]) and chemical contamination (PC1: β = 0.026, 95% CI [-0.075, 0.126]; PC2: β = 0.022, 95% CI [-0.065, 0.109]) were not associated with variation in telomere length. In contrast, climatic conditions and floral characteristics emerged as key predictors of telomere variation, with telomere length declining with increasing mean annual temperature (β = -0.085, 95% CI [-0.158, -0.012]) and increasing floral abundance (β = -0.109, 95% CI [-0.194, -0.024]). Our results indicate that climatic conditions and resource availability are stronger predictors of honeybee telomere length than urbanisation or environmental pollution. These findings suggest that telomere-based patterns of ageing are shaped by the thermal and ecological context experienced by foragers in this key pollinator species.