As fields of crops face a decline in bees bumbling between blossoms, bubbles may offer a new way to spread pollen between crops.
As Cara Giaimo reports for the New York Times, farmers struggling with the decline in commercial honeybees and wild insect populations have turned to alternatives like hiring other insects, pollen-spraying machines and individual pollination by paintbrush. In a paper published this week in iScience, scientists at the Japan Advanced Institute of Science and Technology show that specially designed soap bubbles can deliver grains of pollen to flowering fruit trees. In a pear orchard, the bubbles were just as effective as hand-pollination.
But individually pollinating flowers by hand is tedious, explains study author Eijiro Miyako, a chemist at the National Institute of Advanced Industrial Science and Technology in Japan. When the same research team first tried to pollinate flowers with gel-and-horsehair coated drones in 2017, they found that the machines didn’t have the delicate touch required to transfer pollen, and were sometimes destructive. The idea for bubble-delivered pollen came to Miyako while playing with his son.
"I was playing soap bubbles with my son at a park close to my home, when a soap bubble accidently hit my son's face," Miyako tells Matt McGrath at BBC News. "There was no damage because soap bubbles are soft, light, and flexible."
He realized that the gentle way that bubbles bounce against surfaces and pop without harm could be effective at carrying pollen, too. Miyako and co-author Xi Yang tested several kinds of soap until finding the perfect mixture, a 0.4 percent mix of lauramidopropyl betaine, a common ingredient in baby shampoo, per the New York Times. The soap didn’t interfere with the pollen’s ability to fertilize a flower, and the researchers created bubbles that carried about 2,000 grains of pollen each.
After proving that a bubble could deliver functional pollen to a flower in the lab, the researchers brought their creation to the field. Specifically, a pear orchard. There, Miyako and Yang found that if a flower was hit by between two and ten bubbles, it was just as likely to bear fruit as a hand-pollinated blossom.
“I jumped for joy,” when the technique succeeded, Miyako tells New Scientist’s Layal Liverpool.
Later, the researchers also tested whether the bubbles could be delivered by a drone by flying it above a collection of fake flowers and measuring whether the bubbles hit their targets.
Boston University materials scientist James Bird, who specializes in studying how drops spread and bubbles pop, says that while soap bubbles could be a good way to bring pollen to flowers, they will be difficult to control.
“As most children are aware, the flight path of a bubble can be capricious in even the mildest of breezes, and so this method may be practically limited to orchards blanketed with a high density of accessible flowers,” Bird, who was not involved in the study, tells New Scientist.
And University of Sussex biologist Dave Goulson, who was not involved in the study, tells the New York Times that while the bubbles have “potential” as pollinators, bees are still the best suited for the task. For one thing, bees don’t just deliver pollen—they pick it up in the first place. (Miyako received the pollen for the team’s experiments from the pear orchard’s farmer.)
Goulson tells the New York Times, “It concerns me that our response to the pollination crisis is to find ways to do without pollinators, rather than investing our efforts in looking after our environment better.”