Redirecionar de categoria a pagina

function alter_the_query( $query_vars ) {
     // Ignore if in the admin
    if(is_admin()) {
        return $query_vars;
    }

    // If asking for a category
    if(isset($query_vars['category_name'])) {
        // save the slug
        $pagename = $query_vars['category_name'];
        switch($pagename) {
            case "manzanas":
            case "limones":
                $query_vars = array('pagename' => "category/$pagename");
        }
    }
    return $query_vars;
}