Bees are the most efficient pollinators for many of the crops planted today.
Good pollination for crops such as lavender and canola increases the oil content, whereas for cotton it improves the bole quality. In most fruits good pollination improves quality.
Good pollination in apples requires at least six visits by a pollinator which results in good size and shape, more seeds and a higher calcium content. In large scale plantings honey bees are the only readily available pollinator in sufficient numbers to do the job.
Australia has many feral (wild) bee hives. However there are many agents that singularly or combined with other agents can reduce or eradicate feral hives in your region. Sprays that are deadly to bees can wipe out a feral population of bees (and managed hiv es) very quickly.
Bees suffer from diseases, predators such as birds (rainbow bee eaters), cane toads (if hives are on the ground), small hive beetle and mites that attack the bee brood.
Australia is the only major honey producing country in the world that does not (2013) have the mite - Varroa Destructor. Varroa Destructor has wiped out most feral bee hives and many managed bee hives around the world which has resulted in an increased use of managed pollination hives.