Department of Ecology, Swedish University of Agricultural Sciences, 75007 Uppsala, Sweden.
Oecologia. 2012 Aug;169(4):1025-32. doi: 10.1007/s00442-012-2271-6. Epub 2012 Feb 7.
The relationships between landscape intensification, the abundance and diversity of pollinating insects, and their contributions to crop yield, quality, and market value are poorly studied, despite observed declines in wild and domesticated pollinators. Abundance and species richness of pollinating insects were estimated in ten fields of spring oilseed rape, Brassica napus var. SW Stratos™, located along a gradient of landscape compositions ranging from simple landscapes dominated by arable land to heterogeneous landscapes with extensive cover of semi-natural habitats. In each field, we assessed the contribution of wind and insect pollination to seed yield, seed quality (individual seed weight and oil and chlorophyll contents), and market value in a block experiment with four replicates and two treatments: (1) all flowers were accessible to insects, self and wind pollination, and (2) flowers enclosed in tulle net bags (mesh: 1 × 1 mm) were accessible only to wind and self pollination. Complex landscapes enhanced the overall abundance of wild insects as well as the abundance and species richness of hoverflies. This did not translate to a higher yield, probably due to consistent pollination by honey bees across all fields. However, the pollination experiment showed that insects increased seed weight per plant by 18% and market value by 20%. Seed quality was enhanced by insect pollination, rendering heavier seeds as well as higher oil and lower chlorophyll contents, clearly showing that insect pollination is required to reach high seed yield and quality in oilseed rape. Our study demonstrates considerable and previously underestimated contributions from pollinating insects to both the yield and the market value of oilseed rape.
尽管野生和家养传粉昆虫数量明显减少，但景观集约化、传粉昆虫丰度和多样性及其对作物产量、质量和市场价值的贡献之间的关系仍研究甚少。在十种春油菜（甘蓝型油菜 SW Stratos）田块中，估计了传粉昆虫的丰度和物种丰富度，这些田块位于从以耕地为主的简单景观到具有广泛半自然栖息地的异质景观的景观组成梯度上。在每个田块中，我们评估了风传粉和昆虫传粉对种子产量、种子质量（单粒重和油分、叶绿素含量）和市场价值的贡献，采用了具有四个重复和两个处理的块试验：（1）所有花朵均对昆虫、自花和异花授粉开放；（2）花朵被防虫网套（网眼：1×1 毫米）围住，仅允许风传粉和自花授粉。复杂的景观增加了野生昆虫的总体丰度以及食蚜蝇的丰度和物种丰富度。但这并没有转化为更高的产量，可能是因为所有田块的蜜蜂授粉都很一致。然而，授粉试验表明，昆虫使每株植物的种子增重 18%，并使市场价值提高 20%。昆虫传粉提高了种子质量，使种子更重，油分更高，叶绿素含量更低，这清楚地表明，昆虫传粉是油菜达到高产和高质的必要条件。本研究表明，传粉昆虫对油菜的产量和市场价值有相当大的、先前被低估的贡献。
