ABSTRACT Silkworm, Bombyx mori L. is one of the most important physiological laboratorial tools in scientific and research centers. Many plants contain a variety of chemicals with molting hormone activity in insects. The exogenous administration of these substances is known to affect growth and development of silkworms. Thus in this study methanol extracts of leaf and rhizome of Ajuga reptans, a plant containing phytoecdysteroid were used in 4 concentrations (Viz. 0.312, 0.625, 1.25 and 2.5%) and distilled water as control. Some larvae were treated on the first day of fifth instar and others on fourth and fifth day of fifth instar. All data were analyzed using SAS software and Tukey,s studentized range (HSD) test in a complete randomized design. The results showed that those larvae treated on fourth day, 24 hours after treatment had the largest number of ripe worms at 2.5% concentration of leaf extract (32.666±0.33). Twenty five h after treatment, all treated larvae were significantly different with the control. Number of low cocoons on first day of fifth instar was largest in controls. Shell weights on first day experiment were significantly increased at 0.312% concentration of rhizome extract. The amount of fibroin was highest at 0.625% concentration of leaf extract and the activity of phenoloxidase a key immunity substance was highest at 0.3125% concentration of leaf extract on fourth day of the experiment. It is concluded that the separation of the determined phytoecdysteroid from Ajuga reptans may lead to its commercialization in silk industry.
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