Natural control

• Natural control is the maintenance of population numbers within upper limits and lower limits by the action of a 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 and parasitoids; pathogens are present which destroy the insects.

B. Abiotic control:

• Abiotic factors like temperature, rainfall, sunshine, humidity, mountains, rivers and lakes, etc create the barrier to the increase in insect population by creating unfavorable conditions
• It can be done in the following ways:

1. Climatic factor:

a. Temperature:

• It controls the development, fecundity, feeding, movement, and dispersal of insects.
• WA’s warm moist environment is favorable for the development of most species where the extreme temperature is destructive.
• The optimum temperature is 15-40 degrees 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 pests.

c. Rainfall and Humidity:

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

2. Physical factor

a. Mountain: Large Mountains are barriers to the insect spread. High mountains covered by snow create unfavorable conditions for growth multiplication and spread.

b. Desert: Temperature fluctuation affects the growth and development of insects. In the desert, there is no availability of vegetation for breeding and feeding for the insects. Soil is dry and no availability of water.

c. Sea, lakes, and iver: They create barriers for insects.