  In this paper, we introduce the concept of \emph{Poissonian occupation times}
below level $0$ of spectrally negative L\'evy processes. In this case,
occupation time is accumulated only when the process is observed to be negative
at arrival epochs of an independent Poisson process. Our results extend some
well known continuously observed quantities involving occupation times of
spectrally negative L\'evy processes. As an application, we establish a link
between Poissonian occupation times and insurance risk models with Parisian
implementation delays.
