The pine borer beetle is a parasite to the pine tree. What would most likely happen to the pine tree population if the beetle population decreased?

If the beetle population decreases, the thing that is most likely going to happen is the increase in the number of pine trees. This is the obvious thing that will happen as the pine trees would then be very little affected by the borer beetle and the population of pine tree will flourish very easily. It can be said that the pine trees will get devoid of a harmful parasite.