Identification of receptors responsible for binding of the mannose specific lectin to the gut epithelial membrane of the target insects.

The sap-sucking homopteran insects, commonly known as aphids and leafhoppers are responsible for a huge amount of lost productivity of mustard, chickpea, cabbage, rice and many other important crops. Due to their unique feeding habits and ability to build up a huge population in a very short time, they are very difficult to control. The objective of the ongoing program is to develop insect-resistant crop species through genetic engineering techniques to combat the yield losses, which necessitates the identification of appropriate control elements. In this direction, mannose-binding 25 kDa lectins have been purified from leaves of garlic, Diffenbachia sequina and tubers of Colocasia esculanta. The purified lectins have been analyzed in SDS-PAGE. The effectiveness of these lectins against chickpea aphids, mustard aphids and green leaf hoppers of rice have been tested. The LC(50) value of each lectin against different insects had been monitored [1,2]. Through immunolocalization analysis, the binding of the lectin had been demonstrated at the epithelial membrane of the midgut of the lectin-treated insects [1]. Receptor proteins of brush border membrane vesicle (BBMV) of the target insects, responsible for binding of the lectin to the midgut of the epithelial layer have been purified and analyzed through ligand assay. Biochemical studies have been undertaken to investigate the lectin-receptor interaction at molecular level.