Over a tranquil marsh in Southern California, a drone drops pellets of bacteria known to destroy larvae. Its objective is to address the growing number of mosquitoes that can infect humans with diseases. The Orange County Mosquito and Vector Control District is using drones as its most recent technology to combat mosquito breeding grounds in marshes, sizable ponds, and parks. After California’s unusually wet winter, the spread of the biting insects has become a serious worry. Mosquito eggs laid in water develop into larvae.
“There are quite a bit more mosquitoes due to the rain,” said John Savage, who recently operated the drone at San Joaquin Marsh Reserve near the University of California, Irvine. “You can see out here almost every single marsh pond is full of water.” The area south of Los Angeles, which spans more than 800 square miles (2,070 square kilometres), reports that traps are catching three times as many mosquitoes as they have on average over the previous 15 years. “I would call it a huge spike,” said Kiet Nguyen, a vector ecologist for the district.
The most common ways to apply anti-mosquito treatments involve the utilisation of trucks, helicopters, backpack sprayers, and other airborne vehicles. According to the district, the drone enables more precise treatments and eliminates the need to step on vulnerable terrain. “We’re always looking for advancements in technology — what can get the job (done) more efficiently, more beneficial to the team and less invasive,” Nguyen said.
The drone can access locations that are inaccessible to people using vehicles or backpack sprayers because it is flown higher than all nesting birds
According to Nguyen, the drone can access locations that are inaccessible to people using vehicles or backpack sprayers because it is flown higher than all nesting birds. According to Nguyen, a worker carrying a backpack would need to hike for more than an hour to treat 1 acre (0.4 hectares) of land with a drone. A nearby great egret seemed undeterred as it browsed the long grasses for sustenance as Savage ended a recent morning flight. “We’ve done studies where we watched the birds,” said Savage, “And the birds usually come right back after the drone passes over. So if anything, it’s better for the environment.”
The anti-mosquito treatment is not harmful to other wildlife. “The mosquito larvae are filter feeders, so they feed on the bacteria,” Savage said. “It enters their gut and it’s a growth regulator. So essentially — if you guys have seen the movie ‘Alien’ — it blows their stomach out.” The California Department of Pesticide Regulation’s unmanned aircraft vector control technician licence and a remote pilot licence from the Federal Aviation Administration are both requirements set forth by the district for drone operators. The Orange County district does not use its drone in neighbourhoods despite having it for several years. A drone is also used by Santa Clara County Vector Control to eradicate mosquito larvae in non-residential areas around San Francisco Bay.
Public health threats posed by diseases spread by mosquitoes have long been acknowledged, and concern is growing. This month, the disease prevention agency for the European Union issued a warning that the risk of mosquito-borne viral infections is increasing due to warmth brought on by climate change. The American Centres for Disease Control and Prevention also recorded five cases of malaria this week, which was spread by mosquitoes in Florida and Texas, marking the first local spread in 20 years.
According to the State Department of Public Health, the West Nile virus is the most prevalent and dangerous mosquito-borne disease in California, causing more than 7,500 human cases and more than 300 fatalities since 2003. Although West Nile has not been found in the Orange County district thus far this year, Nguyen is not yet ready to declare triumph over the pests. “It’s more of a battle,” he said. “You’re not going to win the war against mosquitoes, but you can gain some ground. And with advancements in technology, we’re gaining ground.”