ANT NEST

Recently someone pointed out to me two ant nests on the soursop tree in the Fruit Garden.  Occupying the nests were big red ants.  What to do?

I got my student to cut away the lower branch with a pair of shears and that was settled.

However, he had trouble cutting the nest on the upper branch as there was a wire near to it.  Also the ants were crawling all over the branches. Someone suggested using pesticides but then I didn't want to as it might poison the tree as well.

From the expression of my student's face, you can tell that he is feeling rather dejected for not being able to get rid of the ant nest.  So anyone have any suggestions?