Study aims to control mosquitoes by deactivating their sperm

A new study from UC Riverside could help control the infective mosquito by shutting down proteins in its sperm. This would prevent the sperm from swimming or fertilizing eggs.

The research may ultimately help control the Culex mosquito that transmits brain-swelling encephalitis and West Nile virus. As climate change intensifies, a lot of other mosquitoes, such as those that carry malaria, are moving into the Northern Hemisphere.

“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 study first author Cathy Thaler.

Specialized proteins activate the sperm flagella, or ‘tails,’ that power their movement. “Without these proteins, the sperm cannot penetrate the eggs. They’ll remain immotile, and will eventually just degrade,” explained study co-author Richard Cardullo.

The researchers isolated 200 male mosquitoes from a larger population and extracted sperm to detect, identify and profile all proteins. Previously, the team determined that sperm needed calcium to power forward. 

“Now we can look in the completed protein profile we’ve created, find the calcium channel proteins, and design experiments to target these channels,” said Cardullo.

Protein profiling offers a path toward controlling mosquitoes that is more environmentally friendly than spraying pesticides, which also kills good insects and harms other animals. While this could be an effective population control method,  it is not possible or desirable to kill all mosquitoes.

“Mosquitoes are the deadliest animals on Earth. But as much as people hate them, most ecologists would oppose a plan to completely eradicate them. They play an important role in the food chain for fish and other animals,”said Cardullo.

Surprisingly, learning more about Culex sperm motility may help to improve fertility in humans. Human fertility rates have been falling for years, in part due to environmental factors. A better understanding of sperm could help overcome some of these factors.

“Many cells have flagella, or tails, including human respiratory cells as well as cells in our guts,” said Cardullo. “What we learn in one system, such as mosquitoes, can translate to others.”

The study is published in the journal PLoS ONE.

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By Katherine Bucko, Earth.com Staff Writer

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