Earth, somewhere around the year 2215
A hundred years ago, the insects disappeared. As harvests failed and food systems collapsed, as the planet ached under the strain of heat, famine, and illness, researchers around the world began to scramble for a solution, any solution. Geo engineering, lab grown food, mechanical bees.
And a gain of function test to weed out the root of the problem: if plants could grow anywhere, in any soil, and wouldn't need anything to pollinate them, then perhaps the planet could be saved.
A small conglomerate of scientists altered the genome of plants until they were able to hitch a ride inside living flesh. Capable of expelling larger amounts of pollen than ever before, of surviving omnivorously, and of horizontal gene transfer, it was only a matter of time until the not-yet finished research escaped the laboratory and swallowed the planet whole.
But, you know - life has to go on. The planet hasn't stopped spinning. Society adjusted. And humans haven't stopped wanting, and loving, and fighting for the last scraps of safety and happiness.