[Pollinator] Competition among bees

[David Inouye]

Lindström, S. A. M., et al. (2016). "Experimental evidence that 
honeybees depress wild insect densities in a flowering crop." 
Proceedings of the Royal Society B: Biological Sciences 283(1843).
     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).