There is a possibility that agroforestry will also have the ability to reduce the available insects in the area, mainly because of the various crops that will be placed together.
The increase in biodiversity can also reduce the insects that may cause some issues with the crops. Agroforestry also comes with a lot of other benefits aside from the reduction of the insects that are available.
It can also make the soil become more fertile so that the crops will have better yield and will have more high-quality fruits. This can also reduce the chances of erosion to make the trees and shrubs grow stronger while they are planted there.
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.