A backbench MP has become the first sitting member of Canadian Prime Minister Justin Trudeau’s Liberal Party caucus to call on him to resign, after a disastrous by-election defeat.Wayne Long said new leadership was needed “for the future of our party and for the good of our country” in an email to fellow party members that was obtained by Canadian media outlets.Mr Long, who represents a riding in the province of New Brunswick, wrote “the voters have spoken loud and clear and they want a change”.It follows a catastrophic result for Liberals in a by-election on Monday, when they…