Queen traits and colony founding success in harvester ants: implications for ecological restoration

Introduction The initial size of queens in many ant species is often associated with their reproductive potential and the likelihood of establishing a successful colony, yet the specific factors determining colony founding success in keystone harvester ants remain unclear, limiting their effective use in ecological restoration. Objectives (1) To determine how initial queen mass and subsequent mass loss influence survival and early colony development in the harvester ant Messor barbarus (Linnaeus 1767) (2) To assess whether regional origins affect colony founding success. Methods We collected 464 newly mated M. barbarus queens from Spain and Morocco and monitored their survival, worker production, and egg‐laying rate under controlled laboratory conditions for 7 months, analyzing relationships between physiological traits and founding success. Results Mass loss during claustral foundation was strongly associated with queen survival and worker production, with queens losing less mass having significantly higher survival probabilities, while those experiencing mass loss below −50 mg produced more workers. Initial queen mass showed marginally significant positive effects on both survival and worker production. Regional differences were detected, with Spanish queens producing more workers than their Moroccan counterparts. Conclusions Successful colony founding in M. barbarus depends on a delicate balance between energy conservation and investment in the first worker cohort, with mass loss being a stronger predictor of founding success than initial queen mass alone.