Studies on Yellow Mite Polyphagotarsonemus Latus Banks Tarsonemidae Acari and its Management in Bt Cotton

Abstract

Investigations on roving survey and surveillance, biology, screening of Bt cotton newlinegenotypes and management of yellow mite, Polyphagotarsonemus latus were carried newlineout at College of Agriculture, Hanumanamatti in farmer`s field near by newlineKadaramandalagi during kharif 2017 and 2018. Mean infestation of yellow mite newline(2.02/leaf) and predatory mite activity (0.35/leaf) were maximum in Haveri district newlinewhereas mean population of coccinellids, Chrysoperla and spiders were highest in newlineShivamogga. Peak incidence of egg and active stages of yellow mite was observed newlineduring 34th MSW (4.14/leaf) while predatory mite activity maximum during 34th MSW newline(0.95/leaf). newlineThe mean duration of egg, larva and quiescent stage was 2.05, 1.61 and 1.42 newlinedays, respectively. Pre-oviposition, oviposition and post-oviposition periods lasted for newline1.28, 7.95 and 1.22 days, respectively. The mean fecundity was 35.50 per female. The newlinemean length of egg, larva and quiescent larva was 108.34 and#956;m, 148.09 and#956;m and 185.10 newlineand#956;m, respectively whereas; mean breadth of egg, larva and quiescent was 71.59 and#956;m, newline92.22 and#956;m and 116.95 and#956;m. Adult male measured 184.25 and#956;m and 103.92 and#956;m and female newlinemeasured 217.54 and#956;m and 120.47 and#956;m in length and width, respectively. The female and newlinemale lived for 15.59 days and 14.56 days, respectively. During kharif 2017, among the newline20 genotypes screened for morphological characters, Chaitanya (MRC-7377) and newlineSoumya (SRCH-55) noticed as resistant while, Super fibre (KDCHB-407) and Surya newline(Namkot-803) as susceptible. During kharif 2018, further we investigated biochemical newlineparameters of these genotypes and observed that phenol was recorded highest in newlineresistant genotypes Chaitanya (MRC-7377) and Soumya (SRCH-55). Spiromesifen 240 newlineSC at 100 g.a.i./ha and propargite 57 EC at 570 g.a.i./ha were significantly superior in newlinereducing egg and active stages of yellow mite. Howerver, Propargite 57 EC at 570 newlineg.a.i./ha recorded higher cotton yield and higher net returns which was followed by newlinespiromesifen 240 SC at 100 g.a.i./ha. newline