A friend recently excavated next to a foundation that had been insulated with Expanded polystyrene(white bead board). He was horrified to see that the  2" foam was riddled below grade with rodent tunnels and in some places he found swarms of  large black ants. It's hard to say who invaded the foam first.
How does one protect the foam on below grade ICF foundations?
Do rodents or termites move up through the foam?

There are products available, both manufactured blocks and after-market applications for these issues. It also depends on where you are building, as there are different code requirements for use of foam below grade.

The foam has no nutritional value, it is only a covering which can be protected with various methods.