Effect of methanolic leaf extract and fractions of Datura metel on biological traits of spotted bollworm of cotton

摘要

Datura metel leaves were used to prepare methanol at 2.5, 5.0, 7.5 and 10.0 per cent concentrations and its fractions in hexane, chloroform and acetone at 0.5, 1.0, 1.5 and 2.0 per cent for evaluation against spotted bollworm Earias vittella (Fabricius). Contact toxicity of extract/fractions as evaluated by dry film technique indicated 10 per cent methanol extract and 2 per cent hexane and chloroform fraction as most effective treatments. The larval mortality after 4 and 8 h exposures to dry film ofthese treatments ranged from 53.34 to 66.67 and 76.67 to 86.67 per cent, respectively. Larval survival on treated food was minimum (43.34%) in 10 per cent methanol extract and maximum (76.67%) in 0.5 per cent acetone fraction. Biological traits of E. vittella viz,, larval period, pupation, adult emergence and fecundity were adversely affected on account of larval feeding on food treated with extract/fractions for 48 h. Methanol extract (7.5-10.0%) and hexane (2%) also manifested significant deleteriouseffects on various consumption-utilization indices of larvae. Methanol extract 10.0 per cent and chloroform 2.0 per cent also caused strong larval feeding deterrence i. e. 64.24 and 48.28 per cent, respectively.