Natural control

• Natural control is the maintenance of population numbers within upper limits and lower limits by the action of combination of abiotic and biotic factors.
• Due to the different biotic and abiotic factors the pest population fluctuation takes place.
• It is of two types: Biotic control and abiotic control.

A. Biotic control:

• In nature there are different types of predators, parasitoids; pathogens are present which destroyed the insects.

B. Abiotic control:

• Abiotic factors like temperature, rainfall, sunshine, humidity, mountain, river and lakes etc create the barrier for the increase in insect population by creating unfavorable condition.
• It can be done by following ways:

Climatic factor:

a. Temperature:

• It controls the development, fecundity, feeding, movement and dispersal of insect.
• A worm moist environment is favorable for the development of most of species where as extreme temperature is destructive.
• The optimum temperature is 15-40 degree C.

b. Light:

• Different rays of light like X-rays, gamma rays, UV rays and cosmic rays directly affect the development, reproduction and growth of pest.

c. Rainfall and Humidity:

• Rainfall affects the breeding, multiplication and outbreak of insect. Eg Red Pumpkin Beetle (Aulacophora foveicollis) does not lay egg until it comes across moist soil.

Physical factor

1. Mountain: Large Mountains are barriers to the insect spread. High mountains covered by snow create unfavorable condition for growth multiplication and spread.
2. Desert: Temperature fluctuation affects growth and development of insect. In desert there is no availability of vegetation for breeding and feeding for insect. Soil is dry and not availability of water.
3. Sea, lakes, river: They creates barrier for insect.