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ThesisItem Open Access Growth and development of tobacco caterpillar, Spodoptera litura (Fabricius) on different Bt cotton cultivars.(PAU, 2014) Bhullar, Harpal Singh; Gill, R.S.Effect of the two BG cultivars viz., Yuvraj (Cry1Ac + Cry1Ab ) and JKCH 1050 (Cry1Ac ), three BG II cultivars (Cry1Ac + Cry2Ab) viz., NCS 855, Ankur 3028 and MRC 7017 and a non Bt cultivar LH 2076 was studied on growth and development of Spodoptera litura (Fab.). Significantly, higher mortality of 1st instar larvae of S. litura was recorded in BG II cultivars followed by BG cultivars. Similar trend was recorded in case of 3rd and 5th instars larvae but mortality was significantly reduced as compared to 1st instar. Among the plant parts, highest mortality was recorded in leaves followed by squares and bolls and higher mortality was recorded on 105 day old plants as compared to 120 and 135 day old plants among all the instars. First instar larvae did not moult into subsequent instars and failed to pupate on BG II cultivars. Development of 3rd and 5th instar larvae was slow on BG II cultivars. Third instar larvae recorded significantly longer larval duration (15.16 to 15.38 days) and pupal period (8.58 to 8.64 days), lower pupal weight (134.42 to 136.08 mg) and adult emergence (30.83 to 33.06 %) on BG II as compared to BG and non Bt cultivars. Significantly, slow larval and pupal development, low pupal weight and adult emergence of 3rd instar larvae of S. litura was recorded on leaves as compared to squares and bolls. Significantly higher concentration of Cry1Ac was recorded in Yuvraj (4.56μg/g) followed by MRC 7017 (3.92μg/g), Ankur 3028 (3.70μg/g), NCS 855 (3.62μg/g) and JKCH 1050 (3.02μg/g), whereas significantly higher Cry2Ab concentration was recorded in MRC 7017 (20.89μg/g) followed by Ankur 3028 (19.58μg/g) and NCS 855 (18.61μg/g). Development of 1st and 3rd instar larvae was significantly affected at all the concentrations of BG II leaf powder in meridic diet as compared to BG and non Bt, however, 1st instar larvae could not survive and develop further into subsequent instars. Food consumption and utilization indices (CI, GR, AD and ECI) of 3rd instar larvae of S. litura were significantly reduced on BG II cultivars as compared to BG and non Bt cultivars. BG II cultivars having significantly higher trichomes density and leaf area were more preferred for oviposition by females of S. litura.