About Lesson
Based on population presence:
i. Key pest: pest whose populations are always above the damage threshold are called key pest or regular pest. They need constant watch and control. E. g. fruit fly, aphid, cotton ball worm.
ii. Occasional pest: these are those pests whose populations remain low and insignificant for long period of time. They increase to damaging level due to possibility of favorable climatic condition or depletion of natural enemies. E. g. locust
iii. Potential pest: potential pest is those that might be highly injurious if not kept under control by natural enemies like red spider mite.