What species besides man engage in warfare and what conditions promote warfare?

Ants certainly engage in warfare and many, if not most, engage in conflicts over mating. Various primates have been recorded engaging in what can only be called war in order to gain territory and power over neighboring bands or groups. http://www.slate.com/articles/health_and_science/human_evolution/2012/10/chimpanzee_wars_can_primate_aggression_teach_us_about_human_aggression.html

Species that are both social and territorial may engage in warlike activities to hold and extend territory. Even corals engage in warfare with neighboring coral colonies, as time-lapse photography has shown. At the other end of the evolutionary spectrum, chimpanzee troops frequently feature groups of males going out on raiding parties, hoping to capture and kill members of neighboring troops. On the other hand, many herd animals will have a lot of combat between harem-keeping males but not warfare in any real sense. And some anthropologists argue that before humans started holding fixed territory, there was little or no warfare: http://www.wired.com/2013/07/to-war-is-human-perhaps-not/ And nowadays, hard as it may be to believe, human violence overall seems to have decreased greatly as part of a consistent trend: http://www.npr.org/2011/10/07/141156404/is-human-violence-on-the-wane

I believe chimps kill for fun - kind of like street gangs going a wilding

What exactly do you mean by warfare? You might as well ask what other species has developed a civilization removed from the natural evolutionary environment. But if you're thinking about hunting, there are predatory social mammals like wolves and lions that hunt in well-coordinated groups. Otherwise if you're following the conventional definition of warfare as a sustained, highly-organized attack spanning months or years then there is no analogue in the natural world. All of human invention has moved so far outside of evolution that we are the sole determining factor in whatever changes come about next. Really not even environment or disease can compare as an influence on our development. Of course this is just my opinion. There are some biologists that believe the opposite of you and believe we are becoming more altruistic as a species because altruism has survival benefits in the long term, by encouraging stronger social bonding and building assurance of mutual survival efforts.