Soap Bubbles: An Alternative to Bee Pollination
Written By: Paphapin Pairojtanachai
June 20, 2020
Bees act as natural pollinators for many plant species, but in the past decades, bee species have been put on the decline. The causes for this include pesticides, parasites, competition with other pollinators, and climate change.
This past Wednesday, in the iScience journal, a study was published suggesting a possible alternative to bees: using soap bubbles to assist pollination. Eijiro Miyako, an associate professor in the School of Materials Science at the Japan Advanced Institute of Science and Technology, says that without bees, farmers are faced with a crisis because conventional, hand pollination is “tough” and “annoying”. Therefore, an automatic, artificial pollination method needs to be invented for the farmers’ convenience.
According to the study, machine sprays, although they lower human labor and do not depend on insects, are costly and inefficient since pollen grains may be wasted if they miss the flower. For this reason, researchers are more interested in robotic pollinators, which “can detect individual flowers, operate autonomously and be programmed.” Back in 2017, Miyako and his colleagues invented a tiny drone 2 centimeters in diameter to deliver pollen to fruit-bearing plants. This turned out to be unsuccessful because the drone, lacking a controlling system, often bumped into the flowers and damaged them. Afterwards, Miyako decided that he would discover another method for pollination.
One day, Miyako experienced a light bulb moment when he was blowing bubbles at a park with his 3-year-old son. He thought that if the soap bubbles were soft and light enough that they didn’t harm his son when they touched him on the forehead, they could potentially pollinate flowers without destroying them. This thought began the new research for robotic pollination.
Five surfactants — substances that decrease the surface tension of liquids, thus allowing them to spread more easily — were tested during the research. Miyako and his researchers found that lauramidopropyl betaine was the best surfactant due to its soap-like behavior: its foaming ability enables the production of many stable bubbles when the bubble gun is triggered. In addition, this surfactant does the best job in aiding pollen germination and the development of pollen tubes. With the suitable pH and levels of minerals and chemicals, the researchers found that the solution was most successful at “retaining pollen grains on the thin film of the bubbles and transporting them to the targeted flowers.”
Three hours after pollination took place, the results were shown that pollen activity was highest when the bubble method was used compared to other methods. To gain more specific results, the researchers used fluorescence microscopy to determine that the pollen grains from the soap bubbles settled on the flowers’ pistils and that the pollen tubes grew. However, when over 10 bubbles were released, the number of pollen grains on the pistils decreased and the pollen tubes shortened, possibly as a result of toxic accumulation.
In comparison to other pollination methods such as hand pollination, powder pollination, or solution pollination, bubble pollination is undeniably the better technique. After 16 days, the fruits grew at the same volume as that of the conventional methods. Additionally, while the fruit-bearing rate of the control group was only 58%, the group that underwent bubble pollination reached a rate of approximately 95%, similar to that of the group that went through hand pollination. Furthermore, contrasting to powder and solution pollination, which involve the use of around 1,800 milligrams of pollen per flower, soap bubble pollination used only 0.06 milligrams.
With a newly designed pollination method in hand, the researchers conjoined an automatic bubble maker generating 5,000 bubbles in one minute with an autonomous, GPS-controlled drone in order to build a robotic pollinator. Following pollination trials with fake lilies and real pear flowers, the researchers concluded that the new invention can successfully pollinate flowers — with an 87% success rate — if the drones move slow enough so that the bubbles wouldn’t move in clusters and so that the wind wouldn’t pop the bubbles upon reaching the flowers.
Nevertheless, further consideration and extra research are required to improve the procedure even more. Yu Gu, an associate professor of mechanical and aerospace engineering at West Virginia University who has completed a similar study, mentioned that unlike ground-based robots, “drones had more issues when it came to precision, safety and endurance.” Moreover, bubbles couldn’t be utilized all year round since they cannot endure strong wind and rainstorms. Probable health and environmental influences from the soap chemicals would also have to be dealt with. As James Crall, a postdoctoral fellow in the department of organismic and evolutionary biology at Harvard University, voiced, “We get this incredible service from these animals that are remarkably good at flying around [and] locating these little flowers in dense environments, and they do it incredibly efficiently on a massive scale across the globe. I think we're very, very far from being able to imagine replicating all those services that we basically get for free through robotic platforms.”
To end the research subject, both Miyako and Gu stated that “robotic pollination isn't intended to take bees' jobs or to indicate that they're” unnecessary, and that focusing on the preservation of bees is equally important. Therefore, the public shouldn’t switch from supporting the protection of bees to a cheaper, more productive option.
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