termites in a raised bed
We do not have research on beneficial nematodes and termites.
It is normal for termites to occur naturally in the soil. You did not mention the type of wood in your beds. Most likely the wood is starting to break down. The wood is in contact with the soil which speeds up decay. All you can do is replace the wood or look at options for preserving the wood.
See our website http://extension.umd.edu/hgic/learn/materials-building-raised-beds
I was unsure whether the bed of untreated wood could be used this season for continued gardening.
Do you mean because of the termites?
No worries, you can use the garden as usual.