Predicting the ecological impacts of invasive species is impeded by context-dependencies that can mediate the strength of trophic interactions. Reproductive status is a pervasive context across trophic and taxonomic groups, yet has mostly been neglected in studies of invader impact. The present study examines the influence of the reproductive cycle on predatory impacts of a known damaging invasive freshwater crustacean, Gammarus pulex (Amphipoda), using a comparative functional response approach. Across females that were non-ovigerous, or had immature- or mature-stage embryonic broods, all G. pulex exhibited potentially prey destabilising Type II functional responses towards chironomid larvae. Attack rates were highest by immature embryonic brood stages, and significantly lower by mature embryonic brood stages. Conversely, handling times were consistently lower, and hence maximum feeding rates higher, where broods were present as compared to absent. These predatory patterns may reflect changing resource demands for progeny development across the reproductive cycle, the influence of brood bulk, female moult stage and/or motivational aspects of feeding, such as avoidance of filial cannibalism. Accordingly, many aspects of reproduction may alter the intensity of predatory impacts by invasive species. Future studies considering invader impacts should consider the influence of sex and reproductive status to more holistically quantify and predict population-level invader impacts.

上下文依赖性阻碍了入侵物种对生态影响的预测，而上下文依赖性可以调节营养相互作用的强度。生殖状态在营养和分类学群体中普遍存在，但在入侵者影响的研究中却大多被忽略。本研究使用比较功能响应方法，研究了繁殖周期对已知破坏性入侵淡水甲壳类动物伽马鲁斯（Amphipoda）的掠食性影响的影响。在所有无卵，或具有未成熟阶段或成熟阶段的胚胎的雌性中，全部为G. pulex表现出潜在的猎物破坏了对尺虫幼虫的II型功能反应。未成熟的胚胎育雏阶段的侵袭率最高，而成熟的育雏阶段则显着降低。相反，处理时间始终较短，因此，与不存在相比，育雏时的最高饲养速度更高。这些掠夺性模式可能反映了整个生殖周期后代发育的资源需求变化，育雏量的影响，雌性换羽期和/或喂养的动机方面，例如避免了孝子食人。因此，繁殖的许多方面可能会改变入侵物种对掠夺性影响的强度。