Mosquitoes have been genetically modified to carry a disease that causes females to die in the larval stages while males survive. Males do not bite humans so this cuts the risk of malaria as the mosquitoes proliferate. This was not done using mRNA. It was CRISPR gene editing which involves gRNA, hence the confusion.

Note I'm not saying no need to worry. All actions have unintended consequences. Aside from potentially selecting for a resistant super female, mosquitoes are an important part of the food chain in their environment both as food and even more importantly as pollinators.