Crop yields threatened by decline in wild bee populations

Bee populations have been on the decline in recent years, and two new studies published in Science last Thursday highlight not only how serious the decline has been, but also the serious effect that decline could have on our food supply.

The first study drew upon information gathered over 100 years ago, by naturalist Charles Robertson. Robertson — a professor of biology at Blackburn College — spent years, from 1887 to 1916, collecting records of insect pollinators (bees, flies, beetles and butterflies) near his home in Carlinville, Illinois, detailing the different species and plants that they visited.

"Before Robertson, almost all insect collecting was done independently of the plant," said study co-author John Marlin, a research affiliate at the University of Illinois’ Prairie Research Institute, according a Washington University Newsroom article. "Robertson was one of the first to record the insect, the plant it was collected on, to the extent possible what the insect was doing, and other factors, which led to an explosion of information on insect-plant relationships."

[ Related: Wild bees boost harvest more than honeybees ]

The two other co-authors of the study, Tiffany Knight and Laura Burkle, recently recollected samples from part of Robertson's network, and combining their findings with what Marlin had collected in the 1970s, they found all of the flowering plants that Robertson had recorded, but of the 109 species of bees, only around half were still around.

"That's a significant decline. It's a scary decline," said Burkle, an assistant professor of ecology at Montana State University, according to an article on the National Public Radio website.

Further comparison with the records from Robertson's network also showed that some pollinator insects were active before the plants they typically visited were in bloom, other plants weren't visited as often as they used to be, and the amount of useful pollen being carried by those bees they did find had declined.

"The network is still there and still functioning, despite major perturbations," said Knight, a professor of biology at Washington University in St. Louis. "The bees still have food, plants are still getting pollinator service. But the service has declined, the network’s structure is weaker, and its response to future perturbations much less certain."

It's unknown why so many bee species had disappeared from the region. it could be colony deaths due to diseases and parasites, loss of nesting locations, climate change, or a combination of all three.

The second study, conducted by an international team of scientists from 16 different countries, compared 600 crop fields, across 41 crop systems around the world, and examined the differences between those crops with a large and diverse population of wild insects to those with smaller and less diverse populations. Their results showed that those crops with smaller, less diverse wild insect populations had fewer flowers drop seeds or produce fruit. Even the addition of honey bee populations by farmers only compensated for the loss by a small percentage.

"Our study shows that losses of wild insects from agricultural landscapes impact not only our natural heritage but also our agricultural harvests," said Lucas A. Garibaldi of the Black River National University, in Argentina, according to EurekaAlert.org. "We found that wild insects consistently enhanced the number of flowers setting fruits or seeds for a broad range of crops and agricultural practices on all continents with farmland. Long term, productive agricultural systems should include habitat for both honey bees and diverse wild insects. Our study prompts for the implementation of more sustainable agricultural practices."

[ More Geekquinox: Will a newly discovered comet hit the Mars in 2014? ]

There has been a quote floating around the internet that says: "If the bee disappears from the surface of the earth, man would have no more than four years to live. No more bees, no more pollination … no more men!" Although this quote, (likely incorrectly) attributed to Albert Einstein, represents a certain amount of hyperbole, it can't be denied how important wild bees (and other wild pollinators) are to agriculture, our food supply and our quality of life.

"Ecosystem services can depend on biodiversity provided by wild organisms," said Alexandra-Maria Klein, of Leuphana University of Lüneburg, Germany. "Intensified agriculture separates crop production and biodiversity. Our study shows that this separation can have negative consequences for pollination services not buffered by honeybee management. We urgently need more research that informs, but also involves the global and wider society to explore novel management designs for agricultural landscapes."

Geek out with the latest in science and weather.
Follow @ygeekquinox on Twitter!