It depends upon what beetle(s) are the problem. For Colorado potato beetles (both larvae and adults cause damage) there is a strain of
Bacillus thuringiensis (or Bt) that will kill the larvae. The insecticidal fungus
Beauveria bassiana can also be effective... but perhaps too expensive for small-scale gardening. Maybe on a local forum, several gardeners could pitch in & share? Since CPB will attack other Solanaceae, and you are growing many of those
@Varmit , I'm guessing they are one of the problems.
For some beetles, scented traps can help. Japanese beetles are a problem here; scented traps (such as Bonide) are very effective at reducing the population. Properly placed, the traps also lure the beetles away from the garden. I have 2 traps out now, they each catch 100+ beetles per day, which I empty into a bucket of soapy water daily.
For most unwanted insects (including beetles) I used a mix of insecticidal soap, 50/50 alcohol & water (ethyl alcohol is best), along with about a tablespoon of maple syrup and/or cooking oil per quart. The spray kills all soft-bodied insects, and will kill many beetles provided that they are completely wetted. I've mixed pyrethrin into the spray in the past, and that worked well. I just spot spray with a spray bottle, and get little to no leaf damage... but if covering a large area, wash off the spray about an hour later.