It's hard to say what kind of animals, insects and such which lived on the planet before the disaster. All planet seems to have different sorts of life.
After the disaster there was nothing. Without rain and water, nothing could live there. Note that The Caretaker provide the Ocampa with water in the underground city.
Which brings up the question how the Ocampa would get water after The Caretaker died. Of course, before he died, he provided the underground city with energy for five years and due to what was written in the book Caretaker by L.A. Graf, a book which was based on the script for the episode, The Caretaker also provided the Ocampa with all his knowledge so the people in the city could learn and develope.
However, even if there was underground water available, sooner or later it would be used up too.
But I guess that the Ocampa did find a way to create or produce water and they may also have help from the Ocampa on Suspiria's array.