Here are some insecticides that can be used against fruitfly - dimethoate, fenthion and diazinon (these are active ingredients, any available brands can be used). 


These insecticides can be used in combination with the following control measures - monitor the area regularly, maintain good field sanitation, wrap the fruits with newspaper or polyethelene sleeve and use of attractants (pheromones)  to suppress male population of the adult fruitfly.