We had cabinets installed several years ago and one of the toe kick plates has ppb. We are removing the infected pieces. What are the chances of it spreading into our floorboards, plywood, etc.
Anytime you introduce new, unfinished wood to a pre existing structure, it should be treated with BORACARE to insure the wood does not have any type of wood destroying beetle. And once you have in place wood which is infected and displays exit holes from emerging adult beetles, the possibility of some mating and laying eggs is very real.
At this point I would treat as much of the cabinets with Boracare, along with any new wood you install, to insure there is nothing being missed.
Here are direct links to the information and products listed above:
Powderpost Beetle Article: http://www.powderpostbeetles.com/powderpost-beetle-control#furniture