Inhibitory effect of leaf and root bark of Calotropis procera and Parquetina nigrescens on larval midgut enzyme activities of Callosobruchus maculatus

Abstract

The study evaluated the protein content and effect of leaf and root bark of Calotropis procera and Parquetina nigrescens on midgut enzyme activities of the larvae of Callosobruchus maculatus with a view to solving the problem of cowpea infestation caused by C. maculatus. Evaluation of inhibitory effect of the leaf and root bark of C. procera and P. nigrescens on total protease, trypsin, chymotrypsin, α-amylase and lipase was carried out with 0.5% extract of each plant material as inhibitor source for the enzyme inhibitory assays. Midgut enzyme activities of protease, lipase and alpha amylase and protein content were also quantified. The results showed that the protein content in the midgut of the larvae of C. maculatus were 1.48±0.01, 1.51±0.01, 1.36±0.01 and 1.71±0.01 mg ml-1 in first, second, third, and fourth instar larvae respectively and were significantly (P < 0.05) different. Protease activity was higher than both alpha amylase and lipase activities in the insect midgut while inhibition of the extracts of leaf and root bark of C. procera and P. nigrescens on enzyme activities varied across plant materials and stages of instar larva of C. maculatus.