Vijay KumarSimranjit Kaur2021-03-032021-03-032020Simranjit Kaur (2020). Influence of insecticides on growth and development of Bemisia tabaci (Gennadius) infesting cotton (Unpublished Ph.D. Dissertation). Punjab Agricultural University, Ludhiana, Punjab, India.https://krishikosh.egranth.ac.in/handle/1/5810161903The study on ‘Influence of insecticides on growth and development of Bemisia tabaci (Gennadius) infesting cotton’ was undertaken on 50 days old plants of Bt cotton cultivar, RCH 773 under screen house conditions at Entomological Research Farm, Department of Entomology, PAU, Ludhiana during crop season 2018 and 2019. Effect of repeated application of different insecticides (flonicamid 50 WG @ 100 and 200 g/ha, pyriproxifen 10 EC @ 625 and 1250 ml/ha, spiromesifen 22.9 SC @ 250 and 500 ml/ha, fipronil 5 SC @ 1000 and 2000 ml/ha, ethion 50 EC @ 1000 and 2000 ml/ha and bifenthrin 10 EC @ 450 and 900 ml/ha) on the biology and oviposition preference of B. tabaci; biochemical constituents of cotton leaf and relative expression of vit and jhe gene in B. tabaci were recorded. The results revealed that fecundity of whitefly was significantly lower in spiromesifen 22.9 SC @ 500 ml/ha (18.93 and 29.22 eggs/female) and higher in bifenthrin 10 EC @ 900 ml/ha (43.47 and 62.00 eggs/female) and fipronil 5 SC @ 2000 ml/ha (38.99 and 47.04 eggs/female) over untreated control (32.49 and 40.64 eggs/female) during 2018 and 2019, respectively. Pyriproxifen and spiromesifen significantly prolonged the incubation period, total nymphal duration, pupal period and total developmental period and had minimum egg, nymphal and immature stages’ survival of whitefly. Similarly, pyriproxifen and spiromesifen recorded minimum adult longevity, nymphal growth index, growth index of immature stages and resurgence ratio of B. tabaci. Bifenthrin neither prolonged the duration of various developmental stages nor affected nymphal growth index of B. tabaci. However, sex ratio (female:male) of B. tabaci was increased in fipronil (2.18 and 2.03) and bifenthrin (2.06 and 2.00) over untreated control (1.62 and 1.41) during 2018 and 2019, respectively. Spiromesifen (23.89 and 40.33 eggs/leaf) treated plants were least preferred for oviposition by B. tabaci whereas bifenthrin and fipronil (128.78, 250.56, and 123.33, 219.33 eggs/leaf, resp.) treated plants were most preferred over untreated control (81.00 and 120.33 eggs/leaf) during 2018 and 2019, respectively. The results obtained from biochemical studies revealed that bifenthrin and fipronil treated leaves showed increase in total soluble sugar, reducing sugar, total soluble protein, free amino acid and crude protein content of cotton leaf and decrease in starch content over untreated control. Bifenthrin also decreased the total phenol and tannin content of cotton leaves. pH, total soluble sugars, reducing sugars, sucrose and free amino acids had significant positive correlation with fecundity, adult longevity and oviposition preference of whitefly whereas, phenols and tannins had negative correlation. Bifenthrin and fipronil did not show a significant effect on the relative expression of jhe and vit gene in B. tabaci. Overall results confirmed the resurgence of B. tabaci in Bt cotton with repeated application of bifenthrin and fipronil.EnglishThesis