Efficacy of transgenic cotton plant containing the Cry1Ac and Cry2Ab genes of Bacillus thuringiensis against Helicoverpa armigera and Syllepte derogata in cotton cultivation in Burkina Faso

Abstract

As part of the research into alternatives to pyrethroids, to which lepidopteran cotton pests have begun to develop resistance, transgenic cotton expressing two endotoxins (Cry1Ac and Cry2Ab) of Bacillus thuringiensis Berliner ( Bt), in the U.S. germplasms DP50 and Coker 312, was tested under field conditions in Burkina Faso in two contained areas. An untreated (no lepidopteran insecticidal sprays) conventional (non-transgenic) U.S. variety (Coker 312 in 2003; DP50 in 2004 & 2005) and two conventional local varieties (untreated and treated) were utilized in each test as comparators. The experiments conducted in 2003, 2004 and 2005 showed that the transgenic cotton plant significantly reduced larval populations of the cotton bollworm, Helicoverpa armigera, and the cotton leafroller, Syllepte derogata compared to untreated varieties. Plant damage analyses upon maturity revealed significantly higher levels of sound bolls in transgenic cotton plants. Seed cotton yields and lint quality were also higher for the transgenic cotton than for untreated convention varieties. The transgenic variety was always statistically equivalent or superior to the treated conventional one. The transgenic cotton plant expressing two endotoxins (Cry1Ac and Cry2Ab) of B. thuringiensis Berliner ( Bt) can therefore be an alternative to the use of pyrethroids and endosulfan in cotton cultivation in Burkina Faso. This will have dual advantage of significantly reducing the quantities of pesticides sprayed in the cotton fields while protecting yields and quality of lint.