A bumblebee pollinates a blueberry blossom. Rachael Winfree, Rutgers University

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An international team of researchers led by Rutgers University analyzed crop yields from more than 1,500 agricultural sites across six continents and found that a lack of pollinators is limiting global production of important, nutrient-rich foods such as fruits, nuts, vegetables and legumes.

As the researchers reported in a Rutgers University press release, they found that one to two-thirds of all farms in many different locations growing a variety of different crops have fields that no longer achieve optimal yield levels due to a lack of pollinators.

“Our findings raise concerns and provide grounds for optimism,” said Katie Turo, one of the study’s authors and a postdoctoral fellow in the Department of Ecology, Evolution, and Natural Resources at Rutgers School of Environmental and Biological Sciences. “We found widespread yield deficits. But we also believe that with continued investment in pollinator management and research, we can likely improve the efficiency of our existing croplands to meet the nutritional needs of our global population.”

The study “Insufficient pollinator visitation often limits yield in cropping systems worldwide” was published in the journal Natural ecology and evolution.

The team conducted an analysis of over 200,000 “bee visits” to crop flowers recorded in one of the world’s most comprehensive databases on crop pollination.

A native wild bee pollinates blueberry blossoms in a New Jersey field. Molly MacLeod, Winfree Laboratory

CropPol, the open-source database, contains three decades of field observations of pollinators visiting plants. The database was compiled by lead author Rachael Winfree – a professor in the Department of Ecology, Evolution and Natural Resources – in collaboration with colleagues from South America and Europe.

The study is not applicable to important foods like wheat and rice, which do not require pollinators to reproduce. However, bees and other animals are needed to “pollinate and propagate nutrient-rich and interesting foods that we like and that are culturally relevant,” Turo said.

“If you look through a list of crops and think about what fruits and vegetables you would most like to eat – like berries in the summer or apples and pumpkins in the fall – those are the crops that typically need to be pollinated by insects,” Turo added.

When flowers are pollinated, pollen is transferred from the male to the female part of the flower. This fertilizes the plant so that seeds and fruits and young plants can be produced. Pollen can also be transported by water, wind or pollinators such as wild bees, honey bees, other insects and animals such as bats, small mammals, hummingbirds and other bird species.

Previous research by Winfree and other scientists has shown that the reproduction of about 88 percent of all flowering plants worldwide – as well as 76 percent of the world’s most important food crops – is assisted by pollinators.

Because bees visit more flowers and transport more pollen than others, they are generally considered the most effective pollinators.

The Rutgers scientists found that apple, coffee and blueberry crops were most commonly affected by pollinator insufficiency. The researchers discovered yield deficits in 25 different crops in 85 percent of the countries studied.

However, the researchers were able to find a silver lining in the yield deficit issue: Scientists believe the problem could be solved by realistically increasing pollinator visits to individual fields, Turo said. The study found that some fields are already visited by a sufficient number of bees.

If field managers could improve the consistency of pollinator visits in low- and high-yield fields, many of the yield problems identified in the study could be addressed, Turo said.

“The results are significant because crop yields, which measure the amount of crops grown per unit area, are relevant for assessing the adequacy of the world’s food supply relative to population,” Winfree said in the press release. “Our results show that farmers could increase the productivity of agricultural fields by paying more attention to pollinators.”

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