Data from: Experimental evidence that honeybees depress wild insect densities in a flowering crop

While addition of managed honeybees (Apis mellifera) improves pollination of many entomophilous crops, it is unknown if it simultaneously suppresses the densities of wild insects through competition. To investigate this, we added 624 honeybee hives to 23 fields of oilseed rape (Brassica napus L.) over 2 years and made sure that the areas around 21 other fields were free from honeybee hives. We demonstrate that honeybee addition depresses the densities of wild insects (bumblebees, solitary bees, hoverflies, marchflies, other flies, and other flying and flower-visiting insects) even in a massive flower resource such as oilseed rape. The effect was independent of the complexity of the surrounding landscape, but increased with the size of the crop field, which suggests that the effect was caused by spatial displacement of wild insects. Our results have potential implications both for the pollination of crops (if displacement of wild pollinators offsets benefits achieved by adding honeybees) and for conservation of wild insects (if displacement results in negative fitness consequences).

尽管人工饲养的西方蜜蜂（Apis mellifera）可提升诸多虫媒作物的授粉效率，但目前尚不明确其是否会通过竞争关系同时抑制野生昆虫的种群密度。为探究该问题，本研究在两年周期内向23块油菜（Brassica napus L.）田块中投放了624箱西方蜜蜂蜂箱，并确保其余21块田块的周边区域无西方蜜蜂蜂箱分布。研究结果表明，即使在油菜这类大规模开花植物资源生境中，投放西方蜜蜂仍会降低野生昆虫（熊蜂、独居蜂、食蚜蝇、虻类、其他蝇类及其他飞行访花昆虫）的种群密度。该抑制效应不受周边景观复杂度的影响，但随作物田块面积增大而增强，这提示该效应源于野生昆虫遭受的空间排挤。本研究结果既对作物授粉工作具有潜在启示意义（若野生传粉昆虫的空间排挤抵消了投放西方蜜蜂带来的授粉收益），也对野生昆虫的保护实践具有参考价值（若此类排挤会对野生昆虫的适合度产生负面影响）。