If a disease destroying barley plants in a field swept through an ecosystem, what would happen to the barley eating bird populaiton in the field?

It would decrease

Explanation:

In an ecosystem, organisms feed on one another for survival due to the fact that energy needed for metabolic activities in individual organisms can only be obtained via food. This question depicts that certain bird population feeds on barley plant in an ecosystem.

However, If a disease attacks the plants in such a way that it destroys the barley plants in the field, this would cause the barley-eating bird population to DECREASE because their food source has been affected.