Bioefficacy of Bt Cotton Hybrids Containing the Fusion Gene cry1Ac-1Ab Against Spodoptera litura

In the present study, bioefficacy of six Bt cotton hybrids viz., NCEH 2R Bt, NCEH 3R Bt, NCEH 6R Bt, NCEH 13 Bt, NCEH 14 Bt, NCEH 21 Bt carrying fusion gene cry1Ac-1Ab, Bollgard I (Mallika Bt – cry1Ac), Bollgard II (RCH-2 Bt – cry1Ac + cry2Ab), NCEH 2R Non -Bt, and NCEH 3R Non- Bt were evaluated against S litura neonate larvae. Larval mortality and growth inhibition in terms of larval body weight were recorded seven days after treatment. Among the six fusion Bt hybrids tested, lesser mortality of 29.48 per cent and higher mortality of 52.08 per cent was recorded in NCEH 14 Bt and NCEH 3R Bt, respectively whereas, standard check Bollgard II recorded maximum mortality of 56.33 per cent. Fusion Bt hybrids recorded lesser mean weight of live neonate larvae (0.17–0.70 mg) as compared to non Bt hybrids (2.21 mg). The range of reduced body weight and increased mortality recorded in Fusion Bt hybrids is noteworthy to mention in the suppression of S. litura growth.