I take issue with the framing of the industrial-scale farming of introduced species that outcompete native pollinators as a pact between equals. That the bees choose anything.

In your comparison, neither the algae nor the polyps have the capacity to reason about or alter their arrangement.

In a fair deal, both parties must be able to reason about and/or withdraw from the arrangement.

If only one party is able to reason about and withdraw from an arrangement, the other party is being used.

In this case, bees are tools being used. I'm not willing to say that it's a great moral evil for that reason, but bees not only don't have the capacity to understand the arrangement, they will die trying to kill to defend their honey.

So my only appeal in this case is not to pretend that they choose.