Yeasts improve wildflower pollination but herbivores impair

we investigate the isolated and joint effects of two disparate nectarivorous organisms, the ascomycetous yeast Metschnikowia reukaufii and adult herbivorous sawflies, on flower visitation and plant reproductive success in the alpine wildflower Iris bulleyana (Figure 1). In the Hengduan Mountains of SW China biodiversity hotspot (CEPF 2002) where this study was conducted, M. reukaufii is the dominant nectar yeast of I. bulleyana (Deng 2020), and the adult sawfly Tenthredo maculiger frequently bites holes in the perianth tube of iris flowers to consume nectar and nectaries (Ye et al. 2017; Zhu et al. 2017). Specifically, we conducted field experiments using a combination of yeast inoculation and herbivore manipulation treatments to address the following questions: How do nectar yeasts and herbivores affect total flower visits and the frequency of legitimate relative to robbing visits? Is plant reproduction affected indirectly through the yeast-inducted and herbivore-induced changes in legitimate visits, and/or directly affected by microbial and herbivory effects?本研究以高山野生花卉云南鸢尾（Iris bulleyana）为研究对象，探究两种不同的食蜜生物——子囊酵母梅奇尼科夫氏酵母（Metschnikowia reukaufii）与植食性叶蜂成虫——分别以及共同对花朵访花行为及植物繁殖成效的影响（图1）。本研究开展于中国西南山地生物多样性热点区域（CEPF 2002）的横断山区，此前研究显示（Deng 2020），梅奇尼科夫氏酵母是云南鸢尾花蜜中的优势酵母类群；而植食性叶蜂Tenthredo maculiger成虫常通过在鸢尾花花被管上咬洞取食花蜜与蜜腺（Ye等，2017；Zhu等，2017）。具体而言，本研究采用酵母接种与植食者操控相结合的野外实验方案，旨在解答以下科学问题：食蜜酵母与植食性昆虫如何影响花朵总访花频次，以及合法访花相较于盗蜜访花的频率变化？植物繁殖是否会通过酵母与植食者诱导的合法访花行为改变而受到间接影响，同时或直接受到微生物作用与植食作用的影响？