The sawfly larvae (the caterpillar-like insects) are not related to the needle browning. The needle color change in the photo is normal, and many types of evergreens (including pines) shed older foliage in the autumn. It might be exacerbated by the limited root zone given how close the pine is to the building (much too close for its eventual mature stature) and whether it experienced drought stress this summer (it would have, unless watered regularly). After turning yellow or brown, those old needles will fall off and the shedding will stop for the season.

Miri