Best to let mother nature do the job.

If you read that "Orange tree" thread just above this one youll see that
mother nature doesn't always do as good a job as possible
Also in my case the mandarin tree is in a pot plant that has a base that's
regularly filled with water so no ants will be able to get into it without
me helping them with some sort of bridge, so it'd just be up to bees and
small birds. I think I'll give manual pollination a go