I say, you need a bug tracking system, to record bugs, caused by what, reported by, and then assign the bugs, to different people based on their work load. Also indicated whose code caused the bug, and then have a report showing how many coders, and what apps, have caused x number of bugs during the week.
Then you can show that to coders, to show how they are causing bugs.
And the best way to prevent bugs, is to get everyone involved with fixing them. I mean assign a bug fix to different people, to give round-out experience of what causes bugs and what fixes them.
Then maybe after a month or two of everyone fixing bugs, revise or create your coding style guideline to help prevent future bugs, system wide, by having written/documented standards for how you program.