Full sun, strong populations, oil traps, Guardstar soil drench (but only helps "after the fact"). I'm also under the impression that dry, arid conditions help. Going beyond these often noted methods would probably mean going to some type of off-label use of something. The problem is that beetles will keep coming, thus you have to keep doing "something"...my "something" is oil traps along with full sun and doing my best to keep strong hives.
I think Mite-Away-Quick-Strips have been mentioned as killing beetles, but again, more beetles will come so a waiting trap is good.
Ed