Herbivores decrease plant fitness by consuming reproductive tissues, limiting resources, and/or affecting mutualisms. Although these mechanisms were extensively tested in chewing herbivores, the impact of other functional groups (e.g., sap-feeders) remains poorly understood. We investigated whether aphids affect plant reproduction via direct resource limitation on seed production and/or pollination interference. We compared plant traits and the seed set of naturally aphid-free vs. aphid-infested plants and then manipulated aphid presence and pollen receipt. We used path models to examine the links between variables. Nectar volume and seed set of aphid-infested plants was 54% and 42% lower than that of aphid-free plants. 72 h after removing aphids, nectar volume was restored to the level of aphid-free plants. When pollinators were excluded, the seed set of aphid-infested and aphid-free plants did not differ, suggesting that direct resource limitation on seed production was not the cause of reduced plant fitness. Manual addition of pollen restored the seed set of aphid-infested plants to the level of aphid-free plants, evidencing that plants were pollen limited. The path analysis showed a negative link between aphids and the seed set via nectar volume, supporting that nectar shortage caused by aphids may interfere with pollination and reduce plant fitness. Since aphids are crop pests and feed on a large number of animal-pollinated plants, the potential of these insects to influence pollination and plant fitness is high. This study emphasizes the ecological importance of aphids and the need to better understand the links between sap-feeding herbivory, pollination, and plant fitness.

草食动物通过消耗生殖组织，限制资源和/或影响共生关系来降低植物的适应性。尽管在咀嚼食草动物中对这些机制进行了广泛测试，但对其他官能团（例如汁液喂食器）的影响仍然知之甚少。我们调查了蚜虫是否通过对种子生产和/或授粉干扰的直接资源限制影响植物繁殖。我们比较植株性状和种子集自然蚜虫免费的对比蚜虫侵染的植物，然后操纵蚜虫的存在和花粉的接收。我们使用路径模型来检查变量之间的链接。蚜虫侵染的植物的花蜜量和结实率比无蚜虫的植物低54％和42％。去除蚜虫后72小时，花蜜量恢复到无蚜虫的水平。当排除传粉媒介时，蚜虫侵染和无蚜虫的种子集没有差异，这表明直接限制种子生产的资源并不是造成植物适应性降低的原因。手动添加花粉可将受蚜虫侵染的植物的种子集恢复为无蚜虫的植物水平，证明植物的花粉有限。路径分析显示，蚜虫与种子集之间通过花蜜体积负相关，支持由蚜虫引起的花蜜短缺可能干扰授粉并降低植物适应性。由于蚜虫是农作物害虫，并以大量的动物授粉植物为食，因此这些昆虫影响授粉和植物适应性的潜力很高。这项研究强调了蚜虫的生态重要性，以及需要更好地了解以汁液为食的草食，授粉和植物适应性之间的联系的需要。