Winning promotes both perceived and actual fighting ability in dominance contests among bumblebee workers

Dominance contests have important implications for the allocation of limited resources among insect individuals. Prior experiences, particularly winning and losing have been well-documented to influence the performance and outcomes of future contests across various species. This experience effect is believed to arise either from alterations in an individual's self-assessment of its fighting ability based on past experiences or from social cues generated by previous experiences that are subsequently recognized by opponents. However, the influence of previous fighting experiences on dominance contests and the underlying cognitive mechanisms in insects remains underexplored. This study aims to investigate how previous fighting experiences influence the performance and outcomes of dominance contests among bumblebee workers (Bombus terrestris) and the underlying cognitive process. Our research findings indicate that prior winning experiences significantly influence individuals' behavioral decision-making during the pre-escalation phase of contests. Specifically, individuals with previous victories demonstrate a pronounced tendency to initiate and escalate contests, providing compelling evidence that such experiences enhance their self-perceived fighting ability. Furthermore, despite conflict resolution being largely contingent upon escalated contests, prior winners consistently exhibit a markedly higher probability of securing victories. This finding suggests that previous winning experiences improve individuals' actual fighting ability. This enhanced fighting ability enables smaller individuals to overcome larger opponents. Notably, the winner effect persists for a minimum duration of 3 d. In contrast, losers did not show significant changes in performance, suggesting the absence of a pronounced loser effect. These findings provide new insights into the mechanisms underlying the winner effect in insects.