Is there a word for an animal that eats only one type of food? The giant panda, for example, only eats bamboo; koalas only eat eucalyptus leaves. "Monovore" would be ideal, but I don't believe that word exists (at least, it's not in the OED). So an obvious sample sentence would be: "The giant panda is a/an ***** as it only eats bamboo".
: feeding on or utilizing a single kind of food especially : feeding on a single kind of plant or animal
From Merrim Webster Online :monophagous
The noun is monophage.