Scientists are making people 'invisible' to mosquitoes

In stead of making better bug repellent, why not just make people invisible to mosquitoes altogether?

 

Scientists are now experimenting with key smell receptors in these mutant mosquitoes so they would no longer zero in on humans and feed on their blood, Nature.com reports.

 

These findings could help scientists design insect repellents that fight malaria, dengue and agricultural pests brought by mosquitoes, it said.

 

Leslie Vosshall, a neurobiologist at The Rockefeller University in New York who led the latest study, said some species such as Aedes aegypti that carries dengue and yellow fever, and Anopheles gambiae that hosts the malaria parasites prefer humans.

 

While mosquitoes can sense carbon dioxide and body heat, they zero in on humans via body odor.

 

“They love everything about us. They love our beautiful body odor, they love the carbon dioxide we exhale and they love our body heat,” Vosshall said.

 

For now, her team is working out which other sensations repel mosquitoes.

 

“It’s unbelievable to me that people have been spraying DEET on skin for upwards of 60 years. We don’t have any clear idea of how or why it works, and that as a scientist just drives me crazy,” she said.

 

Genetic experiment

 

Vosshall’s team genetically engineered A. aegypti mosquitoes minus the gene orco, which helps build receptor molecules that sense many smells.

 

Minus the Orco protein, mosquitoes had a hard time differentiating honey from glycerol - and humans from other animals.

 

Vosshall likened it to a game show "where the mosquitoes are released into a box and we ask them to choose door number one, where there’s a human arm, or door number two, where there are our beloved guinea pigs.”

 

The mutant mosquitoes that picked the scent of the human arm did not hesitate to approach it, showing orco and the smell receptors it produces can help pick between hosts, but not find and feed.

 

Unable to smell repellent

 

On the other hand, the mutant mosquitoes could not smell the insect repellent DEET from a distance.

 

While the mutants managed to land on a human arm with the repellent they fled instead of fed—possibly suggesting DEET can deter mosquitoes not just via smell but via direct contact.

 

Sensory overload?

 

Laurence Zwiebel, a molecular entomologist at Vanderbilt University in Nashville, said Vosshall's study shows DEET does not work by simply blocking the smells that are conveyed by Orco, as mosquitoes without the gene are still attracted to humans.

 

He said a more likely explanation is that DEET jams a mosquito’s sensory system.

 

“We all know being in a room with too much sensory stimulation is pretty aversive,” he said.

 

For now, Vosshall and Zwiebel are not keen on releasing mosquitoes that cannot discriminate between humans and other animals.

 

Instead, they are working on orco as a possible target for a new generation of insect repellents.

 

Zwiebel’s team is now developing molecules that overactivate the protein to see if it scrambles insects' sense of smell.

 

“We’re not looking to kill these insects, per se, we just want them to feed on something else,” he said.  — TJD, GMA News