I have had no potato bugs in my potatoes because those plants are in another garden. After growing potatoes there for the last 6 or 7 years, I have yet to see a potato bug. (I'm knocking on every piece of wood within reach!)
Nightshade in the other garden is nearly an unknown, as well. There's a little. Maybe 1 plant shows up in about 100 square feet.
In the big veggie garden, where these pictures were taken, there are a couple nightshade plants every 20 square feet. Purslane and pigweed are more common but the nightshade sprouts here and there until I can get it out. I blame the birds but don't really know. The bugs really beat it up and I don't have any trouble getting it out before it goes to seed - something that isn't true with the pigweed for one. At least, the pigweed flowers -- it might be only 1/2" tall when it does that! Remarkable weed . . .
Meanwhile, the nightshade just serves as a food crop for the potato beetles. Then, they move on to the eggplant (big time), tomatoes and the neighbor's potatoes.
Steve