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).