questions: asking about the infestation of insects as well as yellowing of leaves and asking about bitter gourd distance. 
 answers: told him to go for ooze test ( method explained) , spray rogor or dursban @ 2ml / l of water, 3 spray at 5 days interval. apply nutrivate arka  veg special  @ 5- 10 gm / l of water , 2 spray at 15 days interval ( for over all production of plant).
distance for bitter gourd=1.5-2.5m* 60cm-1.2m ( row to row*plant to plant ).