Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, 1465 Mount Vernon Avenue, Marion, OH, 43302, USA.
Department of Entomology, The Ohio State University, 2021 Coffey Road, Columbus, OH, 43210, USA.
Environ Pollut. 2024 Sep 1;356:124316. doi: 10.1016/j.envpol.2024.124316. Epub 2024 Jun 5.
Soil heavy metal contamination is often an unintended byproduct of historic land-use. This contamination can negatively impact resident plants and their interactions with other organisms. Plant fitness in contaminated landscapes depends not only on plant growth, but also on the maintenance of interactions with pollinators. Cadmium (Cd) is a heavy metal that is commonly found in agricultural, urban, and industrial ecosystems as a legacy of historic land-use. It is a prioritized pollutant in soils because of its wide distribution and strong biotoxicity. To understand how Cd influences plant growth and pollinator interactions, we grew sunflowers in media with three different Cd concentrations to represent the range of Cd contamination faced by sunflowers growing on land recovering from past land-use. We measured Cd contamination effects on sunflower morphology and pollinator foraging behavior, specifically the number of visits and visit duration. We then measured seed number and weight to determine if contamination directly or indirectly, as mediated by pollinators, altered plant fitness. Plant height was negatively correlated with Cd concentration, but contamination alone (in the absence of pollinators) did not affect sunflower reproduction. Bumble bees visited sunflowers grown in Exceeding Threshold Cd concentrations less often and for shorter time compared to visits to Below Threshold Cd sunflowers, but honey bees and sweat bees showed similar foraging behavior across Cd contamination treatment levels. Sunflower seed set was positively correlated with the total number of pollinator visits, and sunflowers grown in Exceeding Threshold Cd soil had marginally lower seed set compared to those grown in Below Threshold Cd soil. Our results suggest that at Exceeding Threshold Cd contamination levels plant-pollinator interactions are negatively affected with consequences for plant fitness.
土壤重金属污染通常是历史土地利用的意外副产品。这种污染会对当地植物及其与其他生物的相互作用产生负面影响。受污染景观中植物的适应性不仅取决于植物的生长，还取决于与传粉者维持的相互作用。镉（Cd）是一种常见的重金属，作为历史土地利用的遗留物，存在于农业、城市和工业生态系统中。由于其广泛的分布和强烈的生物毒性，它是土壤中的优先污染物。为了了解 Cd 如何影响植物的生长和传粉者的相互作用，我们在含有三种不同 Cd 浓度的培养基中种植向日葵，以代表向日葵在从过去土地利用中恢复的土地上生长所面临的 Cd 污染范围。我们测量了 Cd 污染对向日葵形态和传粉者觅食行为的影响，特别是访问次数和访问持续时间。然后，我们测量了种子数量和重量，以确定污染是否直接或间接（通过传粉者介导）改变了植物的适应性。株高与 Cd 浓度呈负相关，但单独的污染（没有传粉者的情况下）不会影响向日葵的繁殖。与访问低于阈值 Cd 的向日葵相比，大黄蜂在超过阈值 Cd 浓度下访问向日葵的次数更少，时间更短，但蜜蜂和熊蜂在 Cd 污染处理水平上表现出相似的觅食行为。向日葵种子结实率与传粉者总访问次数呈正相关，在超过阈值 Cd 土壤中生长的向日葵的种子结实率略低于在低于阈值 Cd 土壤中生长的向日葵。我们的结果表明，在超过阈值 Cd 污染水平下，植物-传粉者相互作用受到负面影响，对植物适应性产生影响。
