Lecture 22 : STERIITY METHODS - DEFINITON - PRINCIPLES -
METHODS - REQUIREMENTS AND LIMITATIONS
Sterility method - Definition
Control of pest population achieved by releasing large number of sterilised
male insects, which will compete with the normal males and reduce the insect
population in subsequent generation.
It is usually referred as SIT (Sterile insect technique) or SIRM (Sterile insect
release method)
Sterile insect release method is a genetic control method. This is also called
Autocidal control since insects are used against members of their own species.
E.F. Knipling in 1937 in South East USA used the SIRM technique to control
the screw wormfly (Cochliomyia nominivorax) a serious livestock pest.
The sterile to fertile male ratio, called S:F ratio is important, as the reduction
in reproductive potential of natural population depends on S:F ratio.
The mating with the sterile males will produce inviable or sterile eggs.
Trend of hypothetical population subjected to SIRM
Assumption
1. Female:Male ratio 1:1
2. 1 female produces 5 females as off spring in one generation
No.of females No.of sterile No.of Ratio sterile No. of
Generation without males females to normal fertile
releases released releases(9:1) males females
1. 1,000,000 9,000,000 1,000,000 9:1 100,000
2. 5,000,000 9,000,000 500,000 18:1 26,316
3. 25,000,000 9,000,000 131,579 68:1 1,907
4. 125,000,000 9,000,000 9,535 944:1 10
5. 625,000,000 9,000,000 50 180,000:1 0
In suitable circumstances sterile male release method (SIRM) can be more
effective, compared to insecticide application.
METHODS - REQUIREMENTS AND LIMITATIONS
Sterility method - Definition
Control of pest population achieved by releasing large number of sterilised
male insects, which will compete with the normal males and reduce the insect
population in subsequent generation.
It is usually referred as SIT (Sterile insect technique) or SIRM (Sterile insect
release method)
Sterile insect release method is a genetic control method. This is also called
Autocidal control since insects are used against members of their own species.
E.F. Knipling in 1937 in South East USA used the SIRM technique to control
the screw wormfly (Cochliomyia nominivorax) a serious livestock pest.
The sterile to fertile male ratio, called S:F ratio is important, as the reduction
in reproductive potential of natural population depends on S:F ratio.
The mating with the sterile males will produce inviable or sterile eggs.
Trend of hypothetical population subjected to SIRM
Assumption
1. Female:Male ratio 1:1
2. 1 female produces 5 females as off spring in one generation
No.of females No.of sterile No.of Ratio sterile No. of
Generation without males females to normal fertile
releases released releases(9:1) males females
1. 1,000,000 9,000,000 1,000,000 9:1 100,000
2. 5,000,000 9,000,000 500,000 18:1 26,316
3. 25,000,000 9,000,000 131,579 68:1 1,907
4. 125,000,000 9,000,000 9,535 944:1 10
5. 625,000,000 9,000,000 50 180,000:1 0
In suitable circumstances sterile male release method (SIRM) can be more
effective, compared to insecticide application.
