Mackin Christopher R, Goulson Dave, Castellanos Maria Clara
School of Life Sciences University of Sussex Brighton UK.
Ecol Evol. 2021 Aug 31;11(19):13455-13463. doi: 10.1002/ece3.8068. eCollection 2021 Oct.
With many plant-pollinator interactions undergoing change as species' distributions shift, we require a better understanding of how the addition of new interacting partners can affect plant reproduction. One such group of floral visitors, nectar robbers, can deplete plants of nectar rewards without contributing to pollination. The addition of nectar robbing to the floral visitor assemblage could therefore have costs to the plant´s reproductive output. We focus on a recent plant colonist, , a plant that in its native range is rarely robbed, but experiences intense nectar robbing in areas it has been introduced to. Here, we test the costs to reproduction following experimental nectar robbing. To identify any changes in the behavior of the principal pollinators in response to nectar robbing, we measured visitation rates, visit duration, proportion of flowers visited, and rate of rejection of inflorescences. To find the effects of robbing on fitness, we used proxies for female and male components of reproductive output, by measuring the seeds produced per fruit and the pollen export, respectively. Nectar robbing significantly reduced the rate of visitation and lengths of visits by bumblebees. Additionally, bumblebees visited a lower proportion of flowers on an inflorescence that had robbed flowers. We found that flowers in the robbed treatment produced significantly fewer seeds per fruit on average but did not export fewer pollen grains. Our finding that robbing leads to reduced seed production could be due to fewer and shorter visits to flowers leading to less effective pollination. We discuss the potential consequences of new pollinator environments, such as exposure to nectar robbing, for plant reproduction.
随着许多植物与传粉者之间的相互作用随着物种分布的变化而发生改变，我们需要更好地了解新的相互作用伙伴的加入如何影响植物繁殖。花蜜盗窃者就是这样一类访花者，它们会消耗植物的花蜜回报却不参与授粉。因此，在访花者群体中增加花蜜盗窃行为可能会给植物的繁殖产出带来代价。我们聚焦于一种新近定殖的植物，该植物在其原生范围内很少被盗窃花蜜，但在被引入的地区却遭受严重的花蜜盗窃。在此，我们测试了实验性花蜜盗窃后对繁殖的代价。为了确定主要传粉者行为因花蜜盗窃而发生的任何变化，我们测量了访花率、访花持续时间、被访花朵的比例以及对花序的拒绝率。为了找出盗窃对适合度的影响，我们分别通过测量每个果实产生的种子数和花粉输出量，来作为繁殖产出中雌性和雄性成分的替代指标。花蜜盗窃显著降低了大黄蜂的访花率和访花时长。此外，大黄蜂对有被盗花朵的花序上的花朵访花比例更低。我们发现，被盗处理的花朵平均每个果实产生的种子显著减少，但花粉粒输出量并未减少。我们的发现，即盗窃导致种子产量降低，可能是由于对花朵的访花次数减少且时长缩短，从而导致授粉效果变差。我们讨论了新的传粉者环境（如暴露于花蜜盗窃）对植物繁殖的潜在后果。
