$Acharya N G Ranga Agricultural University, Rajendranagar, Hyderabad - 500 030, Andhra Pradesh, India.
International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru - 502 324, Andhra Pradesh, India.
Introduction of transgenic insect-resistant pigeonpea can be considered as one of the components for minimizing the losses due to Helicoverpa armigera (Hubner). Transgenic pigeonpea plants of ICPL 88039 and ICPL 87 carrying Bacillus thuringiensis cry1Ab and soybean trypsin inhibitor (SBTI) genes were evaluated for resistance to H. armigera under field conditions, as well as in vitro bioassays using leaves, inflorescences, and pods. Lack of significant reduction in leaf feeding, larval survival, and larval weight indicated that the levels of Cry1Ab endotoxin or SBTI present in the transgenic pigeonpea plants were not sufficient. Some plants though showed lower leaf damage, larval survival, and larval weight, owing to the inadequate levels of expression of the transgenes, resistance levels were not consistent. Infestation of transgenic plants with neonate larvae at flowering, supplemented with leaf or pod bioassays under laboratory conditions can be used effectively to evaluate transgenic pigeonpea for resistance to H. armigera.
Transgenic pigeonpea, H. armigera, field evaluation, Bacillus thuringiensis
