Temporal and spatial variation in susceptibility of Helicoverpa armigera (Hübner) populations to Bollgard II BT Cotton in Tamil Nadu, India

The baseline susceptibility of Helicoverpa armigera (Hübner) from major cotton growing areas across Tamil Nadu, India was carried out with RCH 2 (Bollgard II) Bt cotton. Across the populations, Kovilpatti, Theni and Madurai populations were highly susceptible to leaves, squares and bolls of 60, 90, 120 and 150-day-old plants. The lowest mortality was observed in the populations of Attur and Coimbatore. Temporal and spatial variations of toxicity were observed in Bollgard II Bt cotton. The toxicity was higher at 60- day-old plant parts, followed by 90, 120 and 150-day-old. Similarly, the leaves expressed higher toxicity than squares and bolls. Higher toxicity was recorded in detached fresh plant parts bioassayed over the diet incorporation bioassay.

Tropical Agricultural Research Vol. 24 (3): 249-257 (2013)