Australia's bee populations have not been devastated as the island continent has yet to be affected by the Varroa mite. is still not affected or has not yet been affected yet here means TILL NOW not affected . I havent told her yet The band has not yet play the song > The song has yet to be played

Yes, that is exactly what it means. The construction 'has yet to + infinitive' is a slightly more stylish way of saying 'has not yet + past participle'.

Yes, it's just a fancier way of saying "has not yet been affected" or "has not been affected yet". "Australia's bee populations have not been destroyed because Australia has not been affected yet by the Varroa mite."