I read part of this when I was 12 or 13ish about the 1997 time frame and it was not new. I'm pretty sure it was pollen that caused the feral behavior (behavior returned to normal afterwards). Orgies were involved. If i remember correctly hard cover had a lunar eclipse on it.
From the sparse details it sounds vaguely like Darkover Landfall by Marion Zimmer Bradley.
A colony ship goes off course and crashes on an unknown planet. There is some sort of hallucinogenic pollen that cause the colonists to engage in totally uninhibited behavior, including murder and orgies.