Title: Silencing of Midgut Aminopeptidase N of Spodoptera litura by Double-stranded RNA Establishes Its Role asBacillus thuringiensis Toxin Receptor
Abstract: Insecticidal crystal proteins of <i>Bacillus thuringiensis</i> bind to receptors in the midgut of susceptible insects leading to pore formation and death of the insect. The identity of the receptor is not clearly established. Recently a direct interaction between a cloned and heterologously expressed aminopeptidase (<i>slapn</i>) from <i>Spodoptera litura</i>and the Cry1C protein was demonstrated by immunofluorescence and<i>in vitro</i> ligand blot interaction. Here we show that administration of <i>slapn</i> double-stranded RNA to <i>S. litura</i> larvae reduces its expression. As a consequence of the reduced expression, a corresponding decrease in the sensitivity of these larvae to Cry1C toxin was observed. The gene silencing was retained during the insect's moulting and development and transmitted to the subsequent generation albeit with a reduced effect. These results directly implicate larval midgut aminopeptidase N as receptor for <i>Bacillus thuringiensis</i> insecticidal proteins.