Data from: Attracting mutualists and antagonists: plant trait variation explains the distribution of specialist floral herbivores and pollinators on crops and wild gourds

PREMISE OF THE STUDY: Floral traits play important roles in pollinator attraction and defense against floral herbivory. However, plants may experience trade-offs between conspicuousness to pollinators and herbivore attraction. Comparative studies provide an excellent framework to examine the role of multiple traits shaping mutualist and antagonist interactions. METHODS: To assess whether putative defensive and attractive traits predict species interactions, we grew 20 different Cucurbitaceae species and varieties in the field to measure interactions with pollinators and herbivores and in the greenhouse to assess trait variation. Cucurbits are characterized by the production of cucurbitacins, bitter nonvolatile terpenoids that are effective against generalist herbivores but can attract specialist beetles. We determined whether plant traits such as cucurbitacins predict herbivore resistance and pollinator attraction using an information-theoretic approach. KEY RESULTS: Mutualists and floral antagonists were attracted to the same cucurbit varieties once they flowered. However, rather than cucurbitacin concentration, we found that the size of the flower and volatile emissions of floral sesquiterpenoids explained both pollinator and floral herbivore visitation preference across cucurbit taxa. This pattern held across cucurbit taxa and within the Cucurbita genus. CONCLUSIONS: Surprisingly, floral sesquiterpenoid volatiles, which are associated with direct defense, indirect defense, and attraction, rather than defense traits such as cucurbitacins, appeared to drive interactions with both pollinators and floral herbivores across cucurbit taxa. Identifying the relevant plant traits for attraction and deterrence is important in this economically valuable crop, particularly if pollinators and floral herbivores use the same plant traits as cues.研究背景与立论前提：花部性状在吸引传粉者以及抵御花食草动物取食方面发挥着关键作用。然而，植物往往需要在吸引传粉者的醒目性与吸引食草动物的风险之间面临权衡。比较研究为解析多重性状如何塑造互利共生与拮抗互作关系提供了极佳的研究框架。 研究方法：为评估假定的防御性状与吸引性状能否预测物种互作关系，我们在田间种植了20种不同的葫芦科（Cucurbitaceae）物种与变种，以测定其与传粉者和食草动物的互作情况；同时在温室中开展种植实验以评估性状变异。葫芦科植物的典型特征是产生葫芦素（cucurbitacins）——一类具有苦味的非挥发性萜类化合物，可有效抵御广食性食草动物，但却可能吸引专食性甲虫。我们采用信息论方法，探究葫芦素等植物性状是否能够预测食草动物抗性与传粉者吸引能力。 主要结果：开花后，互利共生伙伴（传粉者）与花部拮抗生物（食草动物）会被同一类葫芦科变种所吸引。但研究发现，并非葫芦素浓度，而是花朵大小与花部倍半萜类挥发物的释放量，能够解释不同葫芦科类群间传粉者与花食草动物的访花偏好差异。这一规律在整个葫芦科类群以及南瓜属（Cucurbita）内均成立。 研究结论：令人意外的是，兼具直接防御、间接防御与吸引功能的花部倍半萜类挥发物，而非葫芦素这类防御性状，似乎主导了不同葫芦科类群与传粉者及花食草动物的互作关系。对于这一类经济价值极高的作物而言，明确用于吸引与驱避的关键植物性状具有重要意义，尤其是当传粉者与花食草动物利用相同的植物性状作为觅食线索时。