Bt-cotton can resist American bollworm upto 40 years, says CICR

29 Jul '05

4 min read

The Minister of State for Agriculture, Dr. Akhilesh Prasad Singh informed, in reply to a question in Rajya Sabha that, the study conducted by Central Institute for Cotton Research (CICR) showed that the American bollworm will develop resistance to Bt-cotton after a few years depending mainly on the extent of area under Bt-cotton in the country.

With the current rate of increase in the area under Bt-cotton, it is likely to take about 11-12 years for the pest to develop resistance to Bt-cotton. However, with implementation of proper strategies as suggested by CICR, it is possible to delay resistance by at least 30-40 year, if not more.

A stochastic model 'Bt-Adapt' was developed to simulate the rate of resistance development of H. armigera to Cry1Ac under Indian farming conditions. The model integrates genetic and ecological parameters of H. armigera in relation to its response to the Cry1Ac expressing Bt cotton.

The model can predict the time that would take for bollworm to develop resistance in different cotton-growing districts of the country based on the input statistics of area under Bt-cotton in each of the districts, or even the proposed area to be cultivated under Bt cotton.

Simulation analysis showed that relative survival rate of the Cry1 Ac resistant homozygous (RR), heterozygous (RS) and homozygous susceptible (SS) H. armigera genotypes on Bt cotton, was the most important factor influencing resistance development.

In the order of significance, the other factors that had the greatest impact on resistance development were, the relative proportion of area under Bt cotton, dominance of the resistant allele and initial frequency of resistant alleles in field populations. The extent of population reduction in Bt cotton and non-Bt crops due to pest control, was found to have a significant impact on the rate of resistance development.

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