I remember hearing I think it was a Radiolab episode which talked of an instance where a lot pollination was done by humans, by hand, with paint brushes and pollen. It turned out that the humans were actually better at it than the insects, because they were more consistent. So the result was a crop that was larger than it would have been had insects done the pollinating.

It's kind of a "waste" of human effort to do manual pollination like that rather than having insects do it "for free", but in an emergency, if that's all you've got, then it can be done.

It also seems to me like this kind of work would be ripe for automation with robots or drones somewhere down the line if, say, most bees wound up dying out and humans were forced to pollinate by hand at a large scale.