Several groups have devised devices that mimic pollinating honey bees. In 2017, Eijiro Miyako, a materials chemist at the Japan Advanced Institute of Science and Technology, adapted a 4-centimeter-long toy drone to pollinate flowers. He and colleagues glued horsehairs to the underside of the drone and coated the hairs with a gel to make them stickier and more flexible. The idea was that, just as on a bee, the hairs would pick up pollen from one flower and deposit it on another. Steered by remote control, the drone pollinated lilies, but it damaged the flowers with its propellers.He and a colleague tested various surfactants—detergents that create the soapy film that form bubbles—and picked the one with the least effect on germination (the ability of the pollen grains to grow the tubes that deliver their sperm cells to the ovaries). Then, in lab tests, they bombarded pear flowers with pollen-laden bubbles. When the bubbles popped, the pollen landed on the pistil, the female reproductive part, and the grains grew pollen tubes. But the tubes were shorter than normal if more than 10 bubbles hit the flower, perhaps because of some adverse effect caused by the soap solution, Miyako says.
In a pear orchard, the researchers used a toy bubble gun to blow pollen-laden bubbles on flowers in three trees. After 16 days, the resulting fruit was just as good as that of flowers that had been pollinated by hand, they report today in iScience. The farmers in this orchard, and elsewhere in Japan, traditionally pollinate their pear and apple trees by hand with a feather brush. Miyako says that’s because bees don’t pollinate in low temperatures, and because they sometimes damage the flowers in a way that results in malformed fruits.