重金属的花部积累及其对植物与传粉者适合度的影响.

Soil heavy metal contamination is one of the main issues that Environmental Protection Administration of China has concerned, because it might affect the edible safety of agricultural products and bring fitness consequences of plants and pollinating insects. Recently, high-level nickel in soils was found to be accumulated in floral organs and rewards and the floral accumulation of nickel could affect the foraging behavior of pollinators. However, whether other heavy metals that are among the most common soil heavy metal pollutants could be accumulated in floral organs and rewards and thus affect plant and pollinator fitness has still been unknown. The main aims of this study were to address the following four questions through field survey and artificial control experiments: 1) Are heavy metals in soils accumulated in floral organs and rewards? 2) Do heavy metals accumulated in floral organs and rewards affect plant reproductive fitness? What are its influencing mechanisms? 3) Are heavy metals accumulated in floral rewards accumulated in pollinators via their foraging? 4) Do heavy metals accumulated in pollinators affect their fitness? The investigation of the above four aspects might contribute to estimating the ecological risks of plants and pollinators caused by soil heavy metal contamination, and thus might provide a significant guiding on the protection of plants and pollinators.

土壤重金属污染是我国环境污染关注的重点问题之一，其不仅影响农产品食用安全，也可能影响植物的繁殖行为以及为植物传粉的昆虫行为。最近的研究发现，土壤中高浓度的镍能够在植物的花部器官及花部报酬中积累而影响传粉者的访花行为，但常引起土壤污染的其它重金属能否在植物花部器官与报酬中积累并影响植物与传粉者的行为目前尚未见报道。本项目拟通过野外实验与人工控制实验重点解决以下4个问题：1）土壤重金属能否在开花泌蜜植物的花部器官与花部报酬中积累? 2) 土壤重金属在植物花部器官与报酬中的积累是否会影响植物的繁殖适合度，影响机制如何？3）重金属能否在传粉者食用含重金属的花部报酬后而在传粉者体内积累？4）传粉者体内的重金属积累是否会影响它们的适合度？通过将以上问题的研究结果的整合，有助于了解土壤重金属污染可能对植物、传粉者带来的生态风险，进而为植物及传粉者保护提供指导。

在该项目研究过程中，两种材料即凤仙花和东北玉簪被选择作为研究对象，对其进行重金属处理，处理样的浓度以重金属矿区土壤中检测到的浓度作为标准上下浮动。在对凤仙花花蜜中添加重金属实验中，我们发现当花蜜中重金属积累到一定浓度时，传粉者蜜蜂和熊蜂均减少了访花频率约35%，我们推测很可能是重金属离子改变了花蜜的口感。不过，进一步研究显示，这种访花频率的降低仅仅降低了不到10%的结实率，并未显著影响凤仙花的繁殖适合度。对东北玉簪的实验结果显示，花蜜重金属改变了该植物的传粉体系，减少了盗蜜率50%以上，同时缩短了蜜蜂和熊峰的觅食时间，但提高了蜜蜂和熊峰的访花频率以及玉簪的雌性繁殖适合度。对重金属矿区土壤分析和对污染区产蜂蜜检测都验证了我们的推测，即土壤重金属离子可以积累到花蜜中，并介导到传粉者体内，引起传粉行为并对其生活史某些阶段产生重要影响。