Effect of Microgramma vaccinifolia rhizome lectin on survival and digestive enzymes of Nasutitermes corniger (Isoptera, Termitidae)

Nasutitermes corniger is a termite responsible for biodeterioration of buildings, paintings, books, and monuments. Plant lectins can be environmentally friendly agents for termite control. This work describes the termiticidal activity of Microgramma vaccinifolia rhizome lectin (MvRL) against N. corniger workers and soldiers. Also, it evaluates the possibility that MvRL changes trypsin-like activity as well as activity of cc-amylase, phosphatase, and cellulase in termite gut. MvRL was isolated by chromatography on a chitin column. MvRL, a thermo-stable 17-kDa glycosylated lectin, was inhibited by mannose and glycoproteins. MvRL showed high toxicity against N. corniger (LC50 of 0.130 and 0.085 mg ml(-1) for workers and soldiers, respectively, for 3 days), and did not show repellent and feeding-rejection effects. MvRL. inhibited trypsin-like activity from worker gut extract (K-i of 2.0 mu M), although it did not affect alpha-amylase activities and stimulated acid phosphatase activity from extracts of workers and soldiers by factors of 1.6 and 3.1, respectively. The lectin also stimulated worker endoglucanase activity, and neutralized this activity in soldier gut extract. The beta-glucosidase activity from both castes was inhibited by MvRL. In conclusion, MvRL killed N. corniger workers and soldiers through termiticidal mechanisms that may include their chitin-binding and enzyme-modulating properties. (C) 2012 Elsevier Ltd. All rights reserved.