  In this paper we study an integral invariant which obstructs the existence on
a compact complex manifold of a volume form with the determinant of its Ricci
form proportional to itself, in particular obstructs the existence of a
K\"ahler-Einstein metric, and has been studied since 1980's. We study this
invariant from the view point of locally conformally K\"ahler geometry. We
first see that we can define an integral invariant for coverings of compact
complex manifolds with automorphic volume forms. This situation typically
occurs for locally conformally K\"ahler manifolds. Secondly, we see that this
invariant coincides with the former one. We also show that the invariant
vanishes for any compact Vaisman manifolds.
