Venjakob Christine, Leonhardt Sara, Klein Alexandra-Maria
Ecosystem Functions, Institute of Ecology, Leuphana University of Lüneburg, Lüneburg, Universitätsallee 1, 21335 Lüneburg, Lower Saxony, Germany.
Agroecology, Department of Crop Sciences, University of Göttingen, Grisebachstrasse 6, 37077 Göttingen, Lower Saxony, Germany.
Insects. 2020 Jan 22;11(2):75. doi: 10.3390/insects11020075.
Nectar is crucial to maintain plant-pollinator mutualism. Nectar quality (nutritional composition) can vary strongly between individuals of the same plant species. The factors driving such inter-individual variation have however not been investigated closer. We investigated nectar quality of field scabious, in different grassland plant communities varying in species composition and richness to assess whether nectar quality can be affected by the surrounding plant community. We analyzed (with high performance liquid chromatography) the content of carbohydrates, overall amino acids, and essential amino acids. Amino acid and carbohydrate concentrations and proportions varied among plant individuals and with the surrounding plant community but were not related to the surrounding plant species richness. Total and individual carbohydrate concentrations were lowest, while proportions of the essential amino acids, valine, isoleucine, leucine (all phagostimulatory), and lysine were highest in plant species communities of the highest diversity. Our results show that nectar chemistry varies with the composition of the surrounding plant community, which may alter the taste and nutritional value and thus affect the plant's visitor spectrum and visitation rate. However, the strong inter-individual variation in nectar quality requires additional studies (e.g., in semi-field studies) to disentangle different biotic and abiotic factors contributing to inter-individual nectar chemistry in a plant-community context.
花蜜对于维持植物 - 传粉者的互利共生关系至关重要。同一植物物种个体之间的花蜜质量（营养成分）可能存在很大差异。然而，导致这种个体间差异的因素尚未得到更深入的研究。我们调查了不同草地植物群落中田野山萝卜的花蜜质量，这些群落的物种组成和丰富度各不相同，以评估花蜜质量是否会受到周围植物群落的影响。我们（使用高效液相色谱法）分析了碳水化合物、总氨基酸和必需氨基酸的含量。氨基酸和碳水化合物的浓度及比例在植物个体之间以及与周围植物群落有关，但与周围植物物种丰富度无关。在多样性最高的植物物种群落中，总碳水化合物和单个碳水化合物的浓度最低，而必需氨基酸缬氨酸、异亮氨酸、亮氨酸（均具有刺激摄食作用）和赖氨酸的比例最高。我们的研究结果表明，花蜜化学成分随周围植物群落的组成而变化，这可能会改变花蜜的味道和营养价值，从而影响植物的访客种类和访花率。然而，花蜜质量存在的强烈个体间差异需要进一步研究（例如在半田间研究中），以厘清在植物群落背景下导致个体间花蜜化学成分差异的不同生物和非生物因素。
