I have come across many articles stating that female mosquitoes suck blood from vertebrate hosts to develop their eggs. Some also state that they need proteins, carbohydrates, iron etc., from human blood. But none of them (as far as I know) have stated what components exactly are needed from blood for their egg development. If proteins, what kind of proteins?
According to the Introduction to this paper:
Attractiveness to biting insects is important in medical contexts, mostly in the dynamics of transmission of pathogens by mosquitoes that cause diseases such as dengue and malaria. Blood feeding is an essential part of the lifecycle for most mosquito species as it provides females with the proteins necessary for egg production.
I imagine that the blood protein is simply a rich source of amino acids. This is supported by the finding that an artificial meal consisting of bovine serum albumin can support egg production in Aedes albopictus.
Update following answer from Greg Thatcher
Clearly there is evidence that iron from a blood meal reaches ovaries and eggs, although the paper doesn't provide direct evidence that this iron is essential. However this made me think more deeply about the paper that I cite above about feeding bovine serum albumin as an blood substitute. Could this have also supplied a significant amount of iron? The artificial meal was BSA dissolved in a phosphate-buffered saline. The authors don't specifically address the problem of iron contamination. The main component of PBS is NaCl. If they used AR-grade NaCl then the iron content will have been very low (0.0002% in one example that I found online). However BSA itself can bind metal cations (see here for example) so the protein may have contributed some iron. The authors do quote the source of the BSA that they used but I haven't been able to access a data sheet that might shed light on the level of iron contamination.
Of course it is entirely possible that blood is an essential source of both protein and iron.
What does a female mosquito need from blood?
This paper seems to indicate that iron is the most important ingredient.
To quote from the paper,
Among many nutrients in the blood meal, iron is required for optimal egg development and viable offspring
I would imagine that mosquitoes could get plenty of of proteins by feeding on other parts of the body or plants, but the blood of their chosen victims contains much iron, as hemoglobin requires iron to carry oxygen safely throughout the body.
Mosquitoes generally feed on plant nectar and fruit juice. Male mosquitoes do not take blood, so when you feel a mosquito plunge into your skin and start siphoning your blood, you can bet it is a female, every time. female mosquitoes need nectar for nourishment, they also need protein to develop their eggs. That protein comes from your blood. Once they've gotten blood, the mosquitoes fly away to a warm, damp place to rest and wait for their eggs to develop. That takes up to five days. The females lay their eggs, and then move on to the next blood meal to feed the next batch of eggs.
Female mosquitoes can lay a set of up to 100 eggs about every third night after mating only once. They typically lay as many as three sets before dying.
Those eggs eventually hatch, and the whole mosquito life cycle starts over again.
This is what I got from : tap here