A question about ivermectin (avermectin)

Ivermectin, a large molecule, is modified from avermectin,  biological molecules produced by bacteria. What is the function of avermectin for bacteria? It is unlikely to be against parasites, as it is currently being used for humans. Could its function be antiviral? If so, it would be natural that ivermectin might be effective against coronavirus.

Any information about the biological function of avermectin for bacteria?

Viruses are the biggest enemy for bacteria. Bacteria might be the biggest antiviral experts. We could learn a lot from bacteria.