Refugia Adoption in BT Cotton

What is refugia?

According to GEAC guidelines, every field where Bt cotton is cultivated shall be fully surrounded by a belt of land called ‘refugia’ in which the same non-Bt cotton variety shall be sown.

Proportion of area under refugia?

The size of the refuge belt should be at least five border rows of non-Bt cotton all around the field or 20% of total sown area whichever is more.

Why refugia planting is needed?

✓Refugia are a portion of the farming landscape that do not contain specific Bt genes and generate an abundance of susceptible target pests. These susceptible insects will mate with rare resistant insects that survive on the Bt crop, producing offspring that are killed by the Bt crop. This provides a mechanism o to delay the rate at which resistance to Bt cotton increases in target pest populations, therein promoting the long-term effectiveness of the technology.

✓The main purpose of refugia area is to prevent insects from developing resistance to Bt cotton and therefore farmers who plant Bt cotton seed must also plant non Bt cotton seed. The refugia area supplies a source of wild type (non mutant) insects to mate with possible resistant insects to produce non-resistant insects. Pattern of planting non Bt seeds differs from area to area and farmer to farmer, though the most preferred and suggested pattern is planting non Bt on borders.

✓The insects that have developed resistance to Bt have more chances of mating with an insect that has not developed resistance to Bt. By the laws of genetics, the progenies produced will be insects that are not resistant to Bt.

Availability of refugia in market

Following the guidelines of GEAC each approved Bt cotton seeds variety available in the market in India has two separate packets of 450 gms BG /BG II seeds + 120 gms non Bt seeds of the same hybrid or 120 gms of pigeon pea seeds.

Source: Final Report Impact Evaluation & Socio Economic Study of Bt Cotton, Ministry of Agriculture, GoI.