  We wish to assess the relationship between the population of planetary
nebulae (PNe) and a given parent stellar population from a theoretical point of
view. Our results rely on original population synthesis models used to estimate
the expected luminosity-specific PN density accounting for different
evolutionary scenarios and star formation histories, as observed in galaxies in
the near Universe. For a complete PN sample, we find that 1 PN/1.5E06 L(sun) a
safe (IMF-independent) lower limit to the traced global bolometric luminosity
of the parent stellar population. A tentative application to Virgo cluster data
allows us to place a lower limit at ~7% for the global B luminosity of the
cluster provided by "loose" intergalactic stars.
