Four years after first detecting Asian tiger mosquitos in the San Gabriel Valley, vector control agencies have launched a new effort this summer to fight back against the pesky bug.
The strategy? Mess with their sex life.
“It’s like birth control for mosquitoes,” said Levy Sun, spokesman for the Greater Los Angeles County Vector Control District.
How the Sterile Male Mosquito Pilot Program works
Since late June, the Los Angeles County vector control agency has been working with the San Gabriel Valley Mosquito and Vector Control District and the University of Kentucky to release thousands of sterile, male mosquitoes twice a week in a 5.7 acre area in South El Monte to reduce the invasive species’ population.
At a lab in Kentucky, the male mosquitos, which do not bite and do not transmit disease, are introduced to a strain of bacteria that effectively inhibits the insect’s ability to reproduce.
The bacteria, called Wolbachia, is commonly found in many species of mosquitoes and does not harm them, but if male and female mosquitoes are infected with different strains and they mate, the eggs they reproduce will not hatch.
It’s a phenomenon that scientists call “cytoplasmic incompatibility.”
“The goal of the program is to reduce and hopefully eliminate the invasive tiger mosquitoes in Southern California using this environmentally safe and pesticide free approach,” Sun said.
The spread of Asian tiger mosquitoes
Vector control officials have now detected the Asian tiger mosquito in more than 15 different communities, including Monrovia, West Covina and Covina for the first time this year.
Most recently, the Los Angeles County vector control district announced on Wednesday the tiger mosquito had been positively identified in Silver Lake.
“It’s pretty far reaching,” Sun said, adding that it was not yet clear whether the population found in the Los Angeles neighborhood was part of the batch spreading in the San Gabriel Valley.
What is the Asian tiger mosquito
Distinguished by its black and white stripes and aggressive character, the Asian tiger mosquito bites during the day and is known for spreading dengue fever and the Chikungunya virus. The bug is not native to the United States and likely hitched a ride on imported goods.
Like native mosquitos, the Asian tiger breeds in stagnant water, but, unlike other mosquitos, it can breed in incredibly small quantities of water — a soda can or a water bottle cap, said Wakoli Wekesa, scientific program manager at the San Gabriel Valley vector control district.
This makes it much more difficult to control the mosquito population.
“It’s going to be a problem for the long-term,” Wekesa said.
Why officials are concerned about the invasive mosquito
In January, the Los Angeles Department of Public Health issued an alert asking physicians to keep an eye out for Chikungunya after 50 people who live in the county tested positive for the disease last year. All of them contracted the virus while traveling mostly in Latin American countries.
Although there have been no local transmissions of Chikungunya, the fear is that if an Asian tiger mosquito bites a person positive for the disease it could be transmitted.
At this point, the mosquitos are mostly a nuisance.
Sun said that while vector control officials are still learning about the biological characteristics of the tiger mosquito, he has personally found that their bites are more painful and larger than that of native mosquitoes.
“Their saliva is definitely different than the native mosquito,” he said. “The welts I would get are a lot larger.”
The vector control agencies are continuing to release the sterile mosquitoes through October. Samples of mosquitoes and unhatched eggs will be tested by researchers at the University of Kentucky to determine the success of the program.
If all goes well, the agencies will work to expand the program to more communities next summer.
Residents can report Asian tiger mosquitoes to the control districts in their area by visiting www.reportmosquitoes.org.