  Suppose $A$ is a not necessarily associative algebra with a derivation $d$.
Then $A$ may be considered as a system with two binary operations $\succ $ and
$\prec $ defined by $x\succ y = d(x)y$, $x\prec y = xd(y)$, $x,y\in A$. Suppose
$A$ satisfies some multi-linear polynomial identities. We show how to find the
identities that hold for operations $\prec $ and $\succ $. It turns out that if
$A$ belongs to a variety governed by an operad Var then $\succ $ and $\prec $
satisfy the defining relations of the operad Var$\circ $Nov, where $\circ $ is
the Manin white product of operads, Nov is the operad of Novikov algebras.
Moreover, there are no other identities that hold for operations $\succ $,
$\prec $ on an arbitrary differential Var-algebra.
