Christa Ludwig, a renowned interpreter of Wagner, Mozart and Strauss who starred on the world’s great stages for four decades, had died at her home in Klosterneuburg, Austria. She was 93. Her death was announced Sunday by the Vienna State Opera. A mezzo-soprano who also succeeded in soprano roles, Ludwig made her Vienna State Opera debut in 1955 and sang 769 performances of 42 roles in Vienna and debuted at New York’s Metropolitan Opera in 1959. She sang 119 performances of 15 roles at the Met.