Malaria mosquitoes can’t spot a spermless mate

A female mosquito cannot tell if the male that she has mated with is fertile or ‘sperm less’ and unable to fertilize her eggs, according to a recent study from scientists at Imperial College London.

Public health experts are working towards the eradication of malaria, but there is a recognized need for better and lower cost tools to achieve the eradication goal.

This new study focuses on Anopheles gambiae, the species of mosquito primarily responsible for the transmission of malaria in Africa.

Today’s results lend support to the idea that in the future it will be possible to control the size of the malaria-carrying mosquito population by introducing a genetic change that makes the males sterile. Such a method would rely on females mating unknowingly with such modified males and failing to produce any offspring. A number of these techniques involve disrupting natural mating patterns and to get these to work a really good understanding of mosquito mating and reproduction is essential.

After mating for the first and only time in her life, the female mosquito undergoes certain physiological changes, then eats a blood meal and lays a batch of eggs. For example, female fruit flies can mate with more than one male, helping to ensure their eggs are fertilized.

The scientists produced 100 spermless males for the study by injecting ordinary mosquito eggs with a protein that disrupted the development of their testes and prevented them from producing sperm in adulthood. Importantly, this did not interfere with any other sexual function or behaviors in either the female or the male.

They reached their conclusions after isolating mating mosquito couples in the laboratory and closely observing their behavior and physiology during key stages of reproduction. They tested for the following characteristics in non-fertile mating couples: the males produced functioning seminal fluid, that brought about the same physiological changes in the females; the female laid the same number eggs in the absence of sperm; and the females abstained from sex following their first intercourse, as they do after mating with a fertile male.

Source: Imperial College London, UK



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