Scientists control mosquito menace by deactivating their sperm

Mosquitoes are considered useless and annoying insects by humans. They do, however, play an essential role in maintaining ecological balance. 

UC Riverside scientists have now discovered a "biological control" solution to the mosquito menace. 

They report that inhibiting specific proteins responsible for mosquito sperm activation could be vital in controlling the mosquito population like Culex. It is a common house mosquito that transmits West Nile Virus and brain-swelling encephalitis.

Blocking the proteins

The researchers found that blocking the proteins would prevent sperm from swimming to eggs and fertilizing them.

“During mating, mosquitoes couple tail to tail, and the males transfer sperm into the female reproductive tract. It can be stored there awhile, but it still has to get from point A to point B to complete fertilization,” said Cathy Thaler, the study’s first author, in a press release. 

These specialized proteins are released during ejaculation, activating the sperm flagella, according to the study. As a result, the sperm moves to complete the process of fertilization. Without these proteins, sperm cannot penetrate the eggs and will remain "immotile," eventually degrading. The findings have been reported in the journal PLOS ONE.

Studying 200 male mosquitoes  

To begin this research, the team created a detailed portrait of all the proteins found in mosquito sperm. This was explicitly done to identify the proteins that allow sperm to swim into eggs.

A group of graduate and undergraduate students of the university collated this profile. They isolated over 200 male mosquitoes from a larger population in total. The, their sperms were extracted from their tiny reproductive tracts for mass spectrometry to identify proteins. This laborious process resulted in the development of a comprehensive mosquito protein profile that could be used to control mosquitoes.

This research is critical for controlling mosquito populations in a more environmentally friendly manner than other toxic methods. “We’ve given up on spraying pesticides all over, because that kills everything, good insects and bad, and harms other animals,” Thaler said.

This scientific approach would not diminish the entire mosquito population; rather, some fertile males would become infertile. This is especially important in terms of environmental balance.

The team's next step is to test this method on other mosquito species, particularly those that transmit malaria.

Study abstract:

Mature sperm from Culex pipiens were isolated and analyzed by mass spectrometry to generate a mature sperm proteome dataset. In this study, we highlight subsets of proteins related to flagellar structure and sperm motility and compare the identified protein components to previous studies examining the essential functions of sperm. The proteome includes 1700 unique protein IDs, including a number of uncharacterized proteins. Here we discuss those proteins that may contribute to the unusual structure of the Culex sperm flagellum, as well as potential regulators of calcium mobilization and phosphorylation pathways that regulate motility. This database will prove useful for understanding the mechanisms that activate and maintain sperm motility as well as identify potential molecular targets for mosquito population control.