Managed honeybee colonies are commonly used to help pollinate crops, but wild insects do the job best, finds a new international study.
Fifty authors are listed on the report, which encourages farmers to improve biodiversity near cropland to provide better habitat for the insects.
“The absence of wild insects cannot be completely remedied by adding honeybees,” said Lawrence Harder, a biological sciences professor at the University of Calgary, who contributed to the project.
“There’s something about the pollination of wild insects that can improve on what can be delivered by honeybees, and our interpretation of that is that it’s somehow related to the quality of pollination.”
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In the study, published recently in Science, researchers outline how they analyzed 23 crops pollinated by wild insects — primarily fruit and oilseeds, including canola — in more than 40 crop systems.
Fruit set and seed production improved with wild insect visitation in every case.
Harder said the wild insects move around more between plants than honeybees, covering more flowers and allowing for greater cross pollination.
“There’s no single best pollinator for all crops, and so I think it’s not reasonable to expect honeybees to be the best,” said Harder.
“But I was struck by this strong contrast of the much greater improvement with the addition of wild insects.”
He said the greatest threats to these populations are injudicious pesticide use and increasing crop acres and cultivation that squeezes out nesting sites.
As well, crops are a resource to pollinators only when they are flowering.
The report recommended integrated management policies that use managed species, including honeybees, bumblebees and leafcutter bees, and the maintenance of natural and semi-natural vegetation to encourage wild insects.
“We need a sequence of different species that are providing nectar and pollen to maintain these wild pollinators,” said Harder.
“The natural vegetation that existed before it was turned to agriculture in many cases is quite suitable for providing those kinds of resources. And so the more that unfarmed areas could be maintained in a natural state, the better off, in fact, the agricultural fields would be, because of the availability of these natural pollinators.”
