Studies on the changes in the activities of digestive enzymes in the midgut of silkworm bombyx mori.(l).(lepidoptera: bombycidae) fed with mulberry leaves supplemented with indian bean (dolichos lablab)

Authors:Saravanan Manjula, Selvi Sabhanayakam, Veeranarayanan Mathivanan, Nadanam Saravanan
Int J Biol Med Res. 2010; 1(4): 168-171  |  PDF File


Abstract Aim: To evaluate the changes in the activities of digestive enzymes activities of silkworm supplemented with Indian bean (Dolichos lablab). Method: Finely powdered Dolichos lablab was dissolved in distilled water and diluted to 2.5 %, 5 %, 7.5 % and 10 % concentrations. Fresh mulberry leaves (Morus alba L.) were sprayed by each concentration and were fed to silkworms, from 3rd to 5th instar, five feedings/day. Group 1 larvae received mulberry leaves sprayed with distilled water and served as control, group 2 larvae received 2.5% Dolichos lablab sprayed mulberry leaves, group 3 larvae received 5 % Dolichos lablab sprayed mulberry leaves, group 4 larvae received 7.5 % Dolichos lablab sprayed mulberry leaves and group 5 larvae received 10 % Dolichos lablab sprayed mulberry leaves. Result: Silkworm larvae fed on Morus alba. L. (mulberry) leaves enriched with 7.5 % concentrations of Dolichos lablab, significantly gained more pupa weight, silk length and silk weight as compared to those fed on normal MR2 mulberry leaves. Hence, 7.5% dose was fixed as an effective dose. Further, same study was conducted to find out the changes in the digestive enzymes activities in the midgut occurred in the fourth day of IVth instar larvae. There was a significant increase in the midgut urease, amylase, sucrase and protease activities. But midgut trehalase activity was significantly decreased. Conclusion: The results suggest that coadministration of Dolichos lablab with mulberry leaves at a concentration of 7.5% has enhanced the digestion of ingested food which in turn reflects in the quantity of silk produced.