Extracts of plant leaves have inhibitory effect on the cellulase activity of whole body extracts of insects - a possible recipe for bioinsecticides.
Sami A. J., Shakoori A. R.
Author Affiliation: Institute of Biochemistry and Biotechnology, University of the Punjab, Quid-e-Azam Campus, Lahore, Pakistan.
Proceedings of Pakistan Congress of Zoology 27 : 105-118
Abstract : The total body extracts of a number of insects such as Aulacophora atripennis, Aulacophora abdominalis, Chrotogonus trachypterus, Dysdercus koenigii, Aulacophora foveicollis, Oxya chinensis, Hieroglyphus banian, Coccinella scutellaris, Mylabris pustulata, Apis dorsata and Apis mellifera showed cellulase activity. Since plants are known to produce certain metabolites, which are insect repellent, we tested the extracts of different tissues of a number of local plants like Aloe barbadensis, Polyalthia longifolia, Plumeria acutifolia, Melia azadarach, Vilis lubursca, Psidium guavaja, Syzygium cumini, Mangifera indica, Azadirachta indica, Eucalyptus camaldulensis, Citrus latifolia and Citrus aurantium for their cellulase inhibition activity. All the plant extracts inhibited cellulase activity of insects except for Citrus latifolia, Citrus aurantium and Aloe barbadensis. The extracts of Psidium guavaja, Azadirachta indica, Eucalyptus camaldulensis and Vilis lubursca were potent inhibitors of cellulase enzymes. The extent of cellulase inhibition for other plant extracts was variable. On fractionation by thin layer chromatography, the plant leaf extracts showed more than ten compounds of which flavonoids were identified by treating the chromatogram with HCl fumes and incubating at 100°C. The leaf extract of guava was proven to be an excellent repellent for blister beetles in the field. The spray of extracts of these plants containing flavonoid can ward off the insects pests which will die of starvation thus minimizing the crop losses.