Data from: Feeding the enemy: loss of nectar and nectaries to herbivores reduces tepal damage and increases pollinator attraction in Iris bulleyana

Floral nectar usually functions as a pollinator reward, yet it may also attract herbivores. However, the effects of herbivore consumption of nectar or nectaries on pollination have rarely been tested. We investigated Iris bulleyana, an alpine plant that has showy tepals and abundant nectar, in the Hengduan Mountains of SW China. In this region, flowers are visited mainly by pollen-collecting pollinators and nectarivorous herbivores. We tested the hypothesis that, in I. bulleyana, sacrificing nectar and nectaries to herbivores protects tepals and thus enhances pollinator attraction. We compared rates of pollination and herbivory on different floral tissues in plants with flowers protected from nectar and nectary consumption with rates in unprotected control plants. We found that nectar and nectaries suffered more herbivore damage than did tepals in natural conditions. However, the amount of tepal damage was significantly greater in the flowers with protected nectaries than in the controls; this resulted in significant differences in pollinator visitation rates. These results provide the first evidence that floral nectar and nectaries may be ‘sacrificed’ to herbivores, leading to reduced damage to other floral tissues that are more important for reproduction.

花蜜通常作为传粉者的奖励，但同时也可能吸引植食性动物。然而，植食动物取食花蜜或蜜腺对传粉过程的影响迄今鲜有实验验证。我们在中国西南横断山区，对具有艳丽花被片且花蜜丰富的高山植物碟花鸢尾（Iris bulleyana）开展了研究。该区域内，该植物的花主要被两类访客造访：一类是采集花粉的传粉者，另一类是取食花蜜的植食动物。我们针对碟花鸢尾提出假说：将花蜜与蜜腺作为植食动物的“牺牲对象”，可保护花被片，进而提升传粉者的访花吸引力，并对此进行了验证。我们设置了两组处理：一组为花蜜与蜜腺取食受保护的植株，另一组为未受保护的对照组植株，对比了两组植株不同花组织的传粉效率与植食损伤率。研究发现，在自然条件下，花蜜与蜜腺的植食损伤程度显著高于花被片。但在蜜腺取食受保护的植株中，花被片的损伤程度显著高于对照组，这也导致传粉者访花频率出现显著差异。本研究结果首次证实，植物可将花蜜与蜜腺“牺牲”给植食动物，从而减少对繁殖更为关键的其他花组织的损伤。