Various organisms such as rats, insects, bacteria, virus, fungi etc. which damage the crops and reduce their yield are called Pests.
Cause of pests on the crops:
They have a direct impact on agricultural food production by chewing the leaves of crop plants, sucking out plant juices, boring within the roots, stems or leaves, and spreading plant pathogens.
They feed on natural fibers, destroy wooden building materials, ruin stored grain, and accelerate the process of decay.