Residents were looking for a respite from the ankle-biting mosquitoes that have caused a recent surge of dengue fever in Los Angeles County.
Generally, invasive mosquitoes are called aedes aegypti – essentially disappear from winter to early May in this region.
Instead, complaints to local agencies tasked with controlling pests have increased recently.
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“We haven’t seen them go away as completely as in previous years,” said Suzanne Kluh, general manager of the Greater Los Angeles County Vector Control District.
Their unusual presence adds urgency to the work underway in the 40-foot shipping container housed in Pacoima. It is going to turn into a bustling nursery for thousands of mosquitoes.
This May, the district is set to release large numbers of sterilized male mosquitoes – which do not bite – into parts of Sunland-Tujunga for the third year in a row.
The last two years were promising, with the female population in the two treated neighborhoods declining by an average of more than 80%.
Yet business owners have indicated they are unwilling to pay to expand.
That has created uncertainty about officials’ goal of eventually rolling out the approach across their entire service area, spanning 36 cities and unincorporated communities.
Steve Vetrone, assistant general manager in the Greater LA district.
(Ronaldo Bolaños/Los Angeles Times)
“Unfortunately, this will be a very expensive endeavor,” said Steve Vetrone, the district’s assistant general manager. “I can tell you right now it’s not something we can do with our current operating budget.”
A need, a question and a disappointing answer
aedes aegypti There are new local fixtures. Native to Africa, black-and-white-striped mosquitoes were first found in California in 2013 Landed in LA County Next year.
“Despite our best efforts, they have managed to overtake us, and they are now in every city and community in our district,” and throughout Southern California, Vetrone said. In fact, low-flying, day-biting mosquitoes exist about half In California counties, including Shasta in the far north.
Desperate to find a solution, many are trying so-called sterile insect techniques — including vector control districts in Orange and San Bernardino counties as well as the San Gabriel Valley — and “we’re all hoping this will be a ray of hope for us,” Kluh said.
The idea is quite simple: Release sterile males so that they outnumber wild males – say, 10 to 1 or even 100 to 1. The goal is for the transformed males to mate with the females, producing eggs that will not hatch.
Kluh’s district uses X-rays to sterilize men but there are other methods, such as using genetically modified insects or insects infected with bacteria.
Female mosquitoes are fed different types of blood – pig and cow – to see which produces the most eggs.
(Ronaldo Bolanos/Los Angeles Times)
This technology, although promising, demands time and money.
In California, property owners foot the bill for local mosquito (and other pest) control, with some paying an annual fee called a benefit assessment.
According to Proposition 218, imposing the new fee requires approval from home, apartment and business owners.
To introduce sterile male mosquitoes to a wide swath of the Greater L.A. district, officials are seeking up to $20 per single-family home per year. That would be on top of the $18.97 that homeowners now pay for the agency’s services.
Last April, the district sent 50,000 sample ballots to property owners asking if they would support the increase.
Only 47% of those who returned were in favor of it.
“The data showed that single-family home owners were quite supportive, but fewer business owners with larger parcels and potentially higher balances did not benefit from the additional spending,” Kluh said in an email.
Business owners may not live in the area, but their vote – if their property spans several acres – is given more weight.
Times readers responded favorably, commenting on a story last year about the proposal.
One reader said, “I hate mosquitoes because they love me so much.” “I would happily spend $20 to reduce their population! I probably spend more than that (even more) on repellents.”
Officials have not given up and plan to send out another round of sample ballots next year.
Kluh already has talking points for businesses: Restaurant owners should be interested in making outdoor dining more enjoyable, while apartment owners could lose revenue if their tenants get sick from outbreaks of Zika, chikungunya or yellow fever — all diseases that spread. aedes aegyptiHe said.
creating mosquitoes that cannot breed
On a recent visit to the Pacoima farm, Nicolas Tremblay, a senior vector ecologist for the district, pulled out a small container filled with a handful of what looked like vitamins.
But the clear pill boxes were filled with approximately 6,500 mosquito eggs and bovine liver powder.
Nicholas Tremblay, senior vector ecologist, uses a tape tray to indicate when pill capsules filled with mosquito eggs have been placed in water.
(Ronaldo Bolaños/Los Angeles Times)
The pellets are dropped into trays of water, where the eggs hatch and the larvae eat the powder. It takes about nine days to go from egg to adult.
The males are then driven to Garden Grove, where they are X-rayed. They are then driven back and set free the next day.
“The situation becomes even more dire around August, September, when we will probably reach our peak of production of 72,000 mosquitoes per week,” he said. “All these (trays) will be filled with water and mosquitoes.”
In 2024, the district launched its pilot, releasing approximately 600,000 sterilized men in two Sunland-Tujunga neighborhoods over about five months.
population of aedes aegypti The number of women declined by an average of 82% compared to the control area.
The threat became clear that year, when 18 cases of locally acquired dengue were recorded in California – a sharp increase from the first cases confirmed the previous year.
Last year, the pilot had similar success, although there was also a natural decline in activity across the district.
On a recent visit to the zoo, several hundred mosquitoes flew around in white mesh cages, posing as participants in a study to see which blood they preferred – pig or cow.
“We haven’t completed the testing yet, but it seems they don’t care,” he said.
One thing scientists already know: aedes aegypti People like to bite.
a highly adaptive enemy
Invasive mosquitoes can lay their eggs even in small amounts of water. A bottle cap or crease in a potato chip bag is fair game.
Additionally, mosquitoes in the Greater LA district are resistant to many insecticides.
Now there may be a new concern. Typically, invasive mosquitoes go into a type of hibernation every year.
Kluh said they appear to have mutated in a way that allows them to remain active during the winter.
The warming climate has already extended their growing season and allowed them to move into previously inaccessible areas.
There are no pesticides involved in releasing sterilized males, and there is also an advantage to the insect’s biology: sexually aroused males are adept at finding females.
Many residents are thrilled with this promising device, but others are thrilled by the idea of tampering with nature.
“There are people who are in favor of it and then there are people who are absolutely against because it’s like, ‘You’re playing God,'” Vettron said.
