Agro forestry may have been practised for centuries, but as a science it is really new. The practices involved may or may not affect insect populations: it is too early in the science to know. A specific and large scale experiment would need to be carried out.
The mechanisms governing the insect-pest are yet to be investigated fully, and there have been no studies that compare monoculture or block plantation for pest situations in agroforestry.
I imagine it would differ greatly whether you are studying populations of insects in Africa or in Scotland. Climate, ad climate changes will doubtless have some effect, and maybe a large one.