Effect of biopesticides on diverse breeds of eri silkworm, Samia cynthia ricini

Abstract

A study was undertaken to evaluate the effect of biopesticides viz., neem oil and karanj oil in different concentrations, on the rearing and cocoon parameters of six diverse breeds of eri silkworm viz., Blue green plain (BGP), Yellow plain (YP), Blue green spotted (BGS), Yellow spotted (YS), Blue green zebra (BGZ) and Yellow zebra (YZ) using the most popular Haritha variety leaves during Kharif and Rabi seasons of 2012-13 at Ericulture Laboratory, Regional Agricultural Research Station, Palem as the dietary nutritional management influences the rearing and commercial parameters of silkworm. Of all the treatments, untreated control proved its superiority in rearing and cocoon parameters. The BGP breed nourished with 2 ml/l karanj oil treated leaves was the next best to control (89.9%) with 84.7% effective rate of rearing and recorded the lowest larval duration of 19.59 days. In BGP breed significantly high weight of cocoon was recorded in worms fed on untreated control (2.11 g), 2 ml/l karanj oil (2.12 g) and 5 ml/l karanj oil (2.27 g) with no statistical variation among them and this breed has shown some tolerance to karanj oil treatment. In YP breed, 3 ml/l and 5 ml/l neem oil treatments recorded highest effective rate of rearing (84.29 and 83.21%, respectively), while the least larval duration of 20.21 days was recorded with 3 ml/l neem oil. BGP breed worms fed with leaves from untreated control recorded significantly higher shell ratio (25.6%) followed by 10 ml/l neem oil (16.6%), while in YP breed 3 ml/l neem oil treatment recorded the highest shell ratio of 14.4%.