  In this paper, we study the Ricci flow on closed manifolds equipped with
warped product metric $(N\times F,g_{N}+f^2 g_{F})$ with $(F,g_{F})$ Ricci
flat. Using the framework of monotone formulas, we derive several estimates for
the adapted heat conjugate fundamental solution which include an analog of G.
Perelman's differential Harnack inequality.
