Abstract This study provides the first detailed characterization of the life cycle and reproductive physiology of Linepithema humile in its native range. Sampling over one year revealed clear seasonal patterns in colony composition, with workers dominating year-round, males emerging in spring, and queens produced a few weeks later. Queen density fluctuated seasonally, peaking in spring, but no clear evidence of the large-scale queen executions in spring observed in invasive populations was detected. Laboratory observations, however, confirm that workers can eliminate nestmate queens, suggesting that queen killing is an intrinsic behavior of this species. Comparative analyses of reproductive physiology revealed notable differences between native and invasive queens. Native queens maintain ovarian activity and lay eggs during winter, whereas invasive queens enter a physiological rest, ceasing oviposition. In spring, invasive queens exhibit higher egg-laying rates and ovarian indices than native queens, likely reflecting warmer nest temperatures, reduced interspecific competition, and energy allocation strategies linked to invasion. No differences were observed from late spring through summer, but in autumn invasive queens reduce egg-laying in preparation for winter, whereas native queens maintain their ovarian and egg-laying activity. These findings indicate that while the overall life cycle is largely conserved, key reproductive strategies have diverged. Avoiding winter oviposition may allow invasive colonies to maximize spring worker production, contributing to their ecological dominance. Establishing a native-range baseline thus provides essential context to understand which traits have shifted during invasion and the mechanisms contributing to the global success of L. humile .
Abril et al. (Mon,) studied this question.