Studies were made in the laboratory of the Department of Entomology, Bangladesh Agricultural University (BAU), Mymensingh form November, 1996 to July, 1997. Before commencement of the experiment, larvae of S. obliqua collected from infested bean field were cultured on bean, cabbage, jute and soybean leaves separately in the laboratory. Ten eggs randomly obtained from egg masses laid on the same day in each culture were placed in Petri dish (10 cm diam x 2.5 cm height). These eggs belonged to the second generation of the field collected S. obliqua. Five replicates per food were used. Observation was made daily to examine egg in each replicate. Just after egg hatching, very small larvae were carefully transferred to separate Petri dishes with the help of a soft camel hair brush (0-0). Fresh green leaves of the respective host plant were supplied as food which was renewed at 24 hours interval with removal of uneaten leaves and faeces. Due to difficulty of measuring small quantity of food eaten and faeces expelled by the larvae at early instars, the measurements of food and faeces were recorded daily from the third instar with the help of an electronic balance. After fourth instar, the larvae were transferred to larger glass jar (9 cm height x 8 cm diam) to avoid crowding. Data were carefully taken on larval moulting. When feeding stopped" the larvae were kept undisturbed until pupation. The pupae obtained from various food plants were transferred to separate glass jars of the same size with their mouth covered with fine mesh cotton cloth and observed for adult emergence. The larval and pupal periods were recorded. Food consumption and utilization were determined as: food consumption= food supplied - food after consumption, and food utilization= food consumption- faeces weight (Rockstein 1978). Biochemical analyses of food and faeces particularly for crude protein, fibre and fat were done following the method of AOAC (1980) in the Department of Animal Nutrition, BAU.Morphometric measurements of body length, head width and wing expanse of male and female moths were recorded for each host plant treatment. Body length from the tip of the head to the end of abdomen, head width from widest area of the head, and wing expanse from tip - tip of the forewings were measured with the help of a divider. The measurements of the larvae were taken under normal motionless condition. Weights of final instar larvae and pupae were taken with the help of an electronic balance. From these measurements and observations, the growth indices were calculated as done by Deshmukh et at. (1976).
Growth index = Percentage pupation/Larval period
Larval-pupal index = (Av. larval period (days) on C. capsularsis + Av. pupal period(days) on C. capsulris)/ { Av. larval period (days) on test plant+ Av. pupal period (days) on test plant}
Pupal weight index = [Average pupal weight (g) on test plant]/[ Average pupal weight (g) on C. capsulans]