Field evaluation of Bollgard and Bollgard II against pink bollworm, Pectinophora gossypiella

The toxicity and effect of Bt cotton (Bollgard and Bollgard II) against pink bollworm (PBW) was studied. Larval incidence was noticed in 2^nd week of October, 2012 to 2^nd week of February, 2013. There was no incidence of PBW larva in RCH-2 Bt. The maximum larval population of 0.46 nos./50 bolls was observed at 51^st std week and 0.42 nos./50 bolls at 50^th std week in Bunny non-Bt and RCH 2 non-Bt cotton hybrids, respectively. Larval population of 0.60 nos./50 bolls at 2^nd std week and 0.52 nos./50 bolls during 1^st std week were observed in MCU 12 and DCH 32, respectively while the green boll damage ranged from 16.84% (42^nd std week) to 60.20% (2^nd std week), respectively. Among the cotton genotypes tested, significantly less percentage of locule damage was registered in RCH-2 Bt (0.25–3.00%) followed by Bunny Bt (2.00 to 6.75%) during all pickings. Highest seed cotton yield was recorded in RCH-2 Bt (11.81 q/ha) followed by Bunny Bt (7.40 q/ha), which in turn was on par with RCH 2 non-Bt (7.40 q/ha). Seed cotton yield registered were Bunny non-Bt (6.17 q/ha), DCH 32 (5.65 q/ha) and MCU 12 (5.37 q/ha), respectively.