Question

why do female mosquito need highly nutritions food in the form of human blood

Answer 1

Female Mosquito always need to lay eggs. The human blood it sucks has proteins which allows her to lay eggs. Other animal's blood can't fulfill the need of food to lay eggs. It means that female mosquito can't lay eggs without human blood. That's why she need highly nutritious blood in the form of human blood.

Answer 2

The human blood it sucks provides it protein which helps it to lay eggs.