if you know there are a few pests (of vine weevils [adults]) or the grubs, destroy immediately like squashing it or something. only for small infestations. using insecticides can effect the content of the fruit and make them inedible. It is not related to bonsai as auk is saying, in truth he is right, so denying the truth is closing the gap between plant and death. Another forum such that auk has directed will give better answers, so, for the life of your plant, go there.