Tiny drones may help pollinate crops when dwindling honeybees aren’t enough.
In a honeybee colony, normally it's the female worker bees that go out, gather pollen, and make honey. The male drones only exist to provide the queen with sperm to make more female workers. But, in response to declining honeybee populations, researchers in Japan are putting drones to work. Only these drones are the plastic, remote-controlled kind.
Combining scotch tape, paint brush hairs, a tiny quadcopter, and a failed, forgotten experiment, these interdisciplinary researchers have produced an artificial honeybee. A drone-drone. (Sorry.)
Ten years ago, Eijiro Miyako, a chemist at the National Institute of Advanced Industrial Science and Technology in Japan, was working on creating an ionic liquid—a sticky substance to conduct electricity in devices. But his experiments didn't work out. So he put the goop away in the cabinets and drawers around his lab and forgot about them until he had to move labs two years ago.
"I was truly surprised because the gel still had a really high viscosity," Miyako told me over Skype. "It seemed like a sticky goo, like hair gels or hair wax."
He also noticed, after dropping some of the liquid on the ground, that it was very good at picking up dust. Around the same time, he was watching TV programs about declining honeybee populations and how that was negatively affecting pollination, which gave him an idea. He wondered if he could use the gel to pollinate flowers.
His first thought was to see if the liquid could augment natural pollination carried out by insects. But it was winter so it was a bit tricky to find bugs just crawling around outside.
"I called farmers. Everyone doubted me, because no one had asked them for that kind of favor," Miyako said. "But young farmers, very young farmers, allowed me to go to their farms and look for insects."
He made a family outing of it, collecting bugs from piles of animal dung he found on the farms.
Back in the lab, he coated ants and flies with the goo and put them in a container with some flowers. After a few days, he noted that not only did the goo-covered bugs were able to transfer more pollen, they were also not dead. So the liquid was not only a great pollinator, but it was also non-toxic.
At this point, Miyako had a plan to try and combine the liquid with a remote-controlled drone. But the goo wouldn't adhere easily to plastic. Instead, his team stuck natural hairs from a paintbrush onto double-sided tape, put that on the bottom of a tiny quadcopter, and coated the hairs in the goo.
Miyako had bought 10 drones, and destroyed nine of them. In the paper describing the drone, published today, February 9 in the journal Chem, he wrote, "a certain amount of practice with remote control of the artificial pollinator is necessary."
But eventually he was successful in transferring the pollen from one flower to another.
He credits a few aspects of the liquid for its success in pollination. The team believes the goo adheres to the pollen via Van der Waals forces, weak attractions between molecules in the liquid and the pollen. Then, when the pollinating drone strikes the flower, the sheer act of slapping the flower breaks that weak bond, and the pollen sticks to the flower.
"In nature pollen comes with a liquid substance around it called pollenkitt. This is a liquid sticky substance that's on pollen that enables it to be picked up and to transfer very easily," said Carson Meredith, a professor at Georgia Tech school of Chemical and Biomolecular engineering in a phone interview. "My feeling is that their liquid gel has probably mimicking the natural behavior of the pollenkitt."
The gel is also very soft, flexible, and doesn't degrade over time. It's extremely stable in a variety of temperatures, which makes it ideal for outdoor use.
Meredith also happened to review the paper for publication. He said it was "remarkable" that the gel could so easily stick to and release the pollen. That sort of goldilocks-level of adhesion is tough to come by.
"There's not a tremendous amount that engineers or materials scientists are doing with pollen these days, or ever really," Meredith said. "It hasn't been a topic that engineers have really tried to set about engineering. But it's an important one."
But one drone in a lab isn't enough to battle the effects of declining honeybee populations. Miyako thinks his drones could one day help farmers pollinate their crops when honeybee populations are too small to do the job properly. But it would probably be inefficient to try and train farmers to fly the drones themselves. Instead, Miyako thinks that GPS or artificial intelligence technologies may hold the keys to real-life applications for his drones.
The liquid itself is an intriguing technology, Meredith said. He suggested that it could be useful in other aspects of agriculture, such as very targeted application of pesticides.
In the meantime, Miyako is busy buzzing away on how he can bring his technology into the field.