Scientists in Japan have created tiny drones that pollinate plants; and if bees disappear, the insect-size drones are intended to replace them.
But why switch to organic farming when you can just build exorbitantly priced robots?
Eijiro Miyako, chemist from the National Institute of Advanced Industrial Science and Technology (AIST) in Japan, found the perfect substance for pollen collection in a decade-old bottle of sticky gel from an earlier experiment he stumbled across while cleaning his lab. The substance, an ionic liquid gel, consists of a collection of complex molecules linked in long chains, and it has the optimal stickiness to pick up pollen grains.
Miyako’s group rubbed the sticky gel on ants and flies – other types of pollinators – and put them on flowers. Each bug was soon covered in pollen.
For use with drones, the gel is a dual-purpose substance: It collects and deposits pollen, and also interacts with light waves to camouflage the drones. The camouflage could come in handy in the future as protection against predators if such drones were deployed in swarms. , 
The team then assembled a 1.6-by-1.6-inch remote-controlled drone equipped with tiny hairs similar to the hairs found on bees. Miyako coated the hairs with the gel and flew the drone into the flowers of Japanese lilies. The tiny robot picked up pollen like a natural pollinator. When it was directed to another flower to release the pollen grains, it successfully pollinated the plant just as the researchers hoped it would. 
Being able to use drones to assist pollinators is little more than a pipe dream at this point. Researchers know they work, but there are major hurdles that need to be cleared. Trevor Weatherhead, Executive Director of the Australian Honey Bee Industry Council, says:
“This little machine will certainly pollinate, but how many would you need for, say, 1,000 acres? You have your pumpkins and watermelons where the flowers are in under the leaves themselves, and the bees sort of fly in under – I’m not sure how the robots would be able to get in and out.” 
If you’re wondering why scientists don’t focus more attention on saving the bees instead of potentially replacing them with robots, you’re not the only person asking that question. Biologist David Goulson from the University of Sussex in the UK, wrote in his blog on February 7, 2017 that we should “look after [bees], not plan for their demise.” 
“I would argue that it is exceedingly unlikely that we could ever produce something as cheap or as effective as bees themselves. Bees have been around and pollinating flowers for more than 120 million years; they have evolved to become very good at it. It is remarkable hubris to think that we can improve on that. Consider just the numbers; there are roughly 80 million honeybee hives in the world, each containing perhaps 40,000 bees through the spring and summer. That adds up to 3.2 trillion bees. They feed themselves for free, breed for free, and even give us honey as a bonus. What would the cost be of replacing them with robots?”
Miyako says he wants to lower the cost of the drones, and he’s going to have to. If conservationists used the same drones that Miyako did, that would equal up to $100 dollars per bee. Honeybee hives contain tens of thousands of bees – a hive of 50,000 bees would cost $5 million to replace.
 The Verge