add_action( 'pre_get_posts', 'AS_order_posts_in_menu_admin' );
function AS_order_posts_in_menu_admin( $q ) {
global $pagenow;
if('nav-menus.php' !=$pagenow)
return $q;
if(isset($q->query_vars['post_type']) && $q->query_vars['post_type']== 'post'){
$q->query_vars['orderby'] = 'date';
$q->query_vars['order'] = "DESC";
}
return $q;
}