Island theory of biological control was given by

Island's theory of biological control was given by Smith.
The “Father” of modern biological control, Professor Harry Scott Smith, defined it as the use of natural enemies to control insect pests.
Biological control is the use of living organisms to suppress pest populations, making them less damaging than they would otherwise be. Natural enemies of insects play an important role in limiting the densities of potential pests. These natural enemies include predators, parasitoids, and pathogens.