What would happen if a plague killed most of the prey organisms within a once-healthy ecosystem?

The animals that feed on the prey would no longer have their normal supply of food. Some animals may adapt and find a new food source, but many would die. This would cause a drastic change in everything. Predators would become prey and that would lead to a decrease in population of the animals that didn't die immediately.

D. china is one of the most active places, which could quite possibly mean more agriculture will happen.. and more war machi-    best of luck comrade.