Mosquitoes' last supper

we were surprised to find that about 90 percent of those mosquitoes died within two days after feeding on blood.”

The COPI RNAi does not have an adverse effect on the female mosquitoes for ten days — unless they decide to take a blood meal. “When she does, all hell starts breaking loose, biochemically and anatomically speaking,” Miesfeld said.

“What we think is happening is that if there is protein in her gut, it induces the secretory machinery. It initiates this huge secretion process but it’s defective and causes cells to disintegrate,” he added. “The whole lining of the gut starts to fall apart, allowing the blood to seep into her body.”

In looking at the potential causes, Miesfeld said his team found that removing any one of the COPI subunits causes the whole complex to fall apart. “Based on what we know about the COPI system, it shouldn’t have that strong of an effect,” he said.

“As scientists have been knocking out COPI to learn more about its function over the past couple of years, they have achieved some interesting results,”

Miesfeld added. “Together with our findings they suggest that COPI does a lot more than what people thought.”

Miesfeld envisions that the ultimate goal of this research is to develop a small molecule that works in place of injected RNAi and acts as a specific inhibitor of the secretion process.

For this to be an effective mosquito-selective insecticide, it must not have any effect on humans.

The simplest use would be to soak it into mosquito nets like currently available insecticides that target the mosquito’s nervous system. A slightly more complex strategy would be to include it in a pill that humans take, so the mosquitoes pick up the inhibitor drug when they bite. As part of this strategy, the researchers are looking for genes that are unique to the mosquito and could serve as targets without affecting human health.

To explain, Miesfeld said to imagine a village in the tropics during a rainy season.

“As the mosquitoes hatch in large numbers, the whole population of villagers is ready,” he explained. “As soon as the insects start biting, they take up the inhibitor and before they can bite again, they die in large numbers. Over a few seasons, that can make a difference.”

Miesfeld added it is unlikely there would ever be a silver bullet eliminating mosquito-transmitted diseases like malaria and dengue fever altogether.

“One potential issue with our strategy is genetic changes rendering the mosquitoes immune over time,” Miesfeld said. “Many approaches from different angles will be necessary, and ours could be another tool in the toolbox.”