Drones Dump Mosquitoes on Hawaii

Drones are dropping pods containing thousands of mosquitoes in the forests of Hawaii, USA. And believe it or not, they are actually on a rescue mission. 

For millions of years, there were dozens of species of Hawaiian honeycreepers (members of the finch family Fringillidae). They survived the arrival of Polynesian settlers, but it didn't take long after the European colonizers arrived for things to go south for birds and other wildlife. Whaling ships arrived in the 1800s and brought mosquitoes with them. 

The greatest threat to Hawaiian forest birds is avian malaria, and which is carried by the invasive mosquitoes. At least 33 species of honeycreepers are already extinct, and many of the 17 extant species are critically endangered. 

A partnership between the American Bird Conservancy and a multi-agency organization called Birds Not Mosquitoes is working to save the honeycreeper by targeting and eliminating mosquitoes.  

As crazy as it sounds, this involves releasing male malaria mosquitoes into the wild to mate with wild female mosquitoes. But there is something unique about the former: they have been lab bred and infected with Wolbachia, gram-negative bacteria (a group of bacteria with a thin cellular wall) from class Alphaproteobacteria, that live within insects and block their eggs from incubating. 

Male mosquitoes do not bite and so, cannot transmit malaria. And releasing lab bred mosquitoes infected with Wolbachia into the wild to compete with wild male mosquitoes should be a safe form of biological control. And as female mosquitoes only mate once, introducing infected male mosquitoes to mate with them, would prevent any eggs they lay from hatching and consequently stop new generations of mosquitoes from developing.

The above illustrates the status of mosquito offspring that result from different mating combinations when male and/or female mosquitoes carry Wolbachia. When male and female mosquitoes that are both free of Wolbachia mate, their offspring are also free of Wolbachia. When Wolbachia-infected male mosquitoes mate with Wolbachia-free females, cytoplasmic incompatibility occurs; their eggs don’t hatch; and no viable offspring are produced. Wolbachia-infected female mosquitoes produce viable offspring that carry Wolbachia after they mate with males that either carry Wolbachia or are free of Wolbachia. This reproductive advantage can help Wolbachia spread in mosquito populations. Image credit: EP Caragata, UF/IFAS

It's a long game, but over time, the project hopes to reduce the mosquito population and prevent the loss of more species to extinction. 

Note: Helicopters were initially used to drop half a million mosquitoes in biodegradable pods into the remote locations where the birds and mosquitoes live, but drones are safer and more flexible.