Above and beyond anything else in the thread, this is a lesson I wholeheartedly embrace and wish more GMs would heed.
Doesn't matter what the behavior is. Doesn't matter what system you're using. Reward the behavior you want to see happen, and cause genuine player-affecting complications for the behavior you don't want to see happen.
Murderhoboism arises from both a push and a pull in this sense. The "pull" comes from GMs attempting to punish folks who are naturally inclined to murderhoboism....by putting attention on them, challenging them, forcing them to fight. That's what most such folks want. Giving them what they want--attention, action, immediate consequences--fuels their behavior. It's trying to fight fire with gasoline, teaching them that they can always get a rise out of you and a good fight if they just act out. Boring them is what punishes them: make them sit through dull situations, make them wait unconscious while the other players act, whatever responses achieve the desired end, and then show them how doing things the right way gets them cool action scenes, immediate consequences, attention, praise, rewards, etc.
The "push", conversely, comes from GMs not just failing to give rewards for non-murderhobo behavior, but outright punishing such behavior. I call it the "mercy is a sucker's game" problem. The GM who always or nearly always thinks, "Ah, the party just showed mercy to a captured enemy. That enemy will reconnect with his buddies, alert them to the party's presence, and thus the enemy will be on high alert now!" The GM who makes law enforcement always obstructive and meddlesome and unforgiving and (etc., etc.), who consistently has party allies suddenly reveal treachery and stab the party in the back, etc., etc. This teaches lessons: never trust, kill first, don't take prisoners because doing so is always worse, take whatever you can while you can get it because you'll lose it if you don't, never trust authority figures, always betray your so-called "allies" before they can betray you, and so on.
Be wise. Show restraint. Ask: "If I want to see X, am I giving worthwhile rewards for X?" Because your players will notice, and they'll respond. Show them why doing something is worthwhile, and they'll do it. Consistently give outcomes they don't like for something, and they'll avoid it. Sometimes, what you think is a realistic outcome is not always the most effective thing for getting a game that you actually find fun to run. (The reverse is also true, but I find these problems crop up much more with GMs who have a very fixed idea of what is "realistic" behavior.)