Abstract
The baseline susceptibility of Helicoverpa armigera (Hubner) 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.
Highlights
Cotton is a very important fibre crop in India; farmers loose the cotton yield due to various insect pests at vegetative and reproductive stages of the crop
The current study focused on the assessment of baseline susceptibility of cotton bollworm, H. armigera to the Bollgard II (BG II) Bacillus thuringiensis (Bt) cotton cultivars in Tamil Nadu
Results of the present study revealed that all the populations were highly susceptible to all plant parts of different ages (60, 90, 120 and 150-day-old) of transgenic BG II Bt cotton (RCH 2) (Table 1 and 3) and least susceptible to non-Bt cotton (Table 2 and 4), respectively
Summary
Cotton is a very important fibre crop in India; farmers loose the cotton yield due to various insect pests at vegetative and reproductive stages of the crop. The American bollworm, H. armigera, is the most serious pest, which causes about US $1 billion worth of damage to agricultural crops in India (Gujar et al, 2000). During 2005 second generation Bollgard II (BG II) cultivars were introduced which contains, two Bt toxins, Cry 1Ac and Cry 2Ab, and offer an improved pest management compared to Bollgard cultivars (Vitale et al, 2008). Baseline susceptibility of H. armigera to Cry 1Ac toxin in India is known (Gujar et al, 2000 & Jalali et al, 2004) but there are no data on the extent of variability in H. armigera susceptibility to BG II cultivars in Tamil Nadu. The current study focused on the assessment of baseline susceptibility of cotton bollworm, H. armigera to the BG II Bt cotton cultivars in Tamil Nadu
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
