Flower infestation by pathogens may influence pollination effectiveness. At the same time, by sharing infested flowers, pollinators increase transmission of pathogens. In the presented study we identified fungi that colonised flowers of the invasive alien Himalayan balsam Impatiens glandulifera, one of the most nectar rewarding plants in Europe, as well as its pollinators. We determined factors (e.g., plant size, length of flower lower sepal and the width of its entry, air temperature and sun illuminance) that affect pathogen species presence and pollinators numbers. The study was conducted in three regions in Poland differing in time from the I. glandulifera invasion onset. It allowed embedding our results in the context of the evolution of increased competitive ability (EICA) hypothesis. With reference to this hypothesis we tested whether I. glandulifera from the two younger populations are more frequently pollinated than individuals from the old one, which may be a result of the higher infection prevalence in the flowers of individuals from the latter population. Harmful primary pathogens of I. glandulifera (e.g., Botrytis cinerea and Fusarium graminearum) were identified from its flowers. Although the knowledge of the impact of the recorded pathogen species on the pollinators that transmit them is still limited, these pathogens are known to cause devastating diseases of native plant species and to incur significant economic losses in crops. Therefore, the facilitation of their transmission by I. glandulifera in the invaded communities may pose a serious threat both to native biodiversity and nearby crop production. We did not find support for the EICA hypothesis that flower release from pathogens may increase the pollinator’s activity. Bombus hortorum was the most frequent visitor in the youngest surveyed population, while B. pascuorum was most frequent in the two others. So far the dominance of B. hortorum as a pollinator of I. glandulifera has not been recorded. A possible explanation is that flowers in the youngest population, with significantly wider entries than in the two older ones, were more accessible for this large bumblebee. We suggest that the shifts in flower dimensions may result from the evolutionary processes and/or phenotypic plasticity; however, this suggestion needs to be confirmed in further studies. At the same time, it can be expected that exceptionally frequent visits of B. hortorum in flowers of I. glandulifera in the youngest population may contribute to increasing transmission rate of pathogen species to the new native host plants that are particularly associated with this pollinator.

中文翻译：

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凤仙花的花朵作为传粉媒介和病原体的中心

 病原体侵染花朵可能会影响授粉效果。同时，通过分享受感染的花朵，传粉者增加了病原体的传播。在本研究中，我们发现了在外来入侵性喜马拉雅凤仙花凤仙花及其传粉昆虫花朵上定植的真菌，喜马拉雅凤仙花是欧洲最有花蜜回报的植物之一。我们确定了影响病原体物种存在和传粉媒介数量的因素（例如植物大小、花下萼片长度及其入口宽度、气温和阳光照度）。这项研究是在波兰的三个地区进行的，这些地区与 I. mudulifera 入侵发生的时间不同。它允许将我们的结果嵌入到竞争能力增强（EICA）假设的演化背景中。参考这个假设，我们检验了 I 是否. 来自两个较年轻种群的腺体比来自较老种群的个体更频繁地授粉，这可能是由于来自后一个种群的个体的花中感染率较高的结果。从其花中鉴定出 I. mudulifera 的有害主要病原体（例如灰葡萄孢和禾谷镰刀菌）。尽管关于记录的病原体物种对传播它们的传粉媒介的影响的了解仍然有限，但已知这些病原体会引起本地植物物种的毁灭性疾病，并给农作物造成重大经济损失。因此，在被入侵的社区中，I. mudulifera 促进它们的传播可能对当地生物多样性和附近的作物生产构成严重威胁。我们没有找到支持 EICA 假设的证据，即病原体释放的花朵可能会增加传粉者的活动。霍托鲁姆熊 (Bombus hortorum) 是最年轻的受调查人群中最常造访的鸟类，而另两种被调查人群中最常造访的则是白熊熊 (B. pascuorum)。迄今为止，B. hortorum 作为 I. mudulifera 的传粉者的优势尚未被记录。一种可能的解释是，最年轻的种群中的花朵比两个较老的种群中的入口明显更宽，因此大黄蜂更容易接近。我们认为花尺寸的变化可能是由于进化过程和/或表型可塑性造成的；然而，这一建议需要在进一步的研究中得到证实。同时，可以预见，B. hortorum 在 I. 花中的访问异常频繁。