County buzzes with mosquitoes amid stagnant water influx

Dr. Mustapha Debboun from the Delta Mosquito & Vector Control District encourages residents to clear litter and leaves from their surroundings in order to prevent mosquito repopulation

VISALIA – After storms swept through the Central Valley this year, stagnant water became a concern for Visalia’s vector control district as mosquitoes staked their claim on flooded areas.

Unraked leaves, planters, toys, littering of water bottles and cans all carry stagnant water, according to Dr. Mustapha Debboun from the Delta Mosquito & Vector Control District. In order to keep residents safe from mosquitoes during such a wet year, Debboun said that people are going to have to work alongside the vector control district to make that a reality.

“We’re here for [residents] to protect them from mosquito bites and also for mosquito borne diseases and to work with them. Together we can definitely reduce the problem,” Debboun said. “It’s a team effort.”

Mosquitoes lay eggs in stagnant water frequently, and not just one egg at a time, Debboun said that a female mosquito can lay roughly 500 eggs at once. Residents may see mosquitoes gravitate to their homes if there is a lot of standing water or litter. The influx of water scattered throughout the area could possibly result in an increase in a mosquito population, however the vector control district will be measuring that throughout the mosquito season.

“We’re definitely looking forward to working with everyone and helping everybody,” Debboun said. “This is what we do, and we will do our best to keep people safe, but people will probably see some mosquitoes, and that’s okay. They’re gonna be out there. There is nothing we can do except to do the best we can to minimize the problem.”

In order for residents to protect themselves, Debboun encourages them to pick up any items that could carry water, or to at least cover them up. For fountains and pools, Debboun says to either keep them chlorinated, running or entirely empty. Not only that, but he said people should wear an EPA-approved mosquito repellent if they plan to go outside this summer. They can also put screens for nets over doorways, windows and any opening to their homes to ensure mosquitoes stay outside. The vector control district can also set up mosquito traps around people’s homes.

“My biggest thing is to ensure that we are part of the public health to prevent people from getting mosquito borne diseases, and also to prevent their dogs from getting diseases because some mosquitoes do transmit heartworm disease [to dogs],” Debboun said.

Residents are not the only ones who can help mitigate the effects of stagnant water, but the vector control district also plays a crucial role in keeping the mosquito population down. Not only do they spray pesticides in areas that are necessary, but they also are distributing mosquito-eating fish to the public, for those that have bodies of water that may be stagnant, such as small ponds. All people have to do is head to their main compound on Houston Avenue in Visalia, and they will distribute fish in plastic bags if residents do not bring their own container. The vector control district also assesses mosquitoes throughout the county for any viruses they may carry.

“Our mission is to go out there and survey and find the areas where the problems are with mosquitoes. We bring mosquitoes back to the laboratory and diagnose them to find if they have any viruses,” Debboun said.

The viruses that some mosquitoes can carry locally are St. Louis Encephalitis Virus, Western Equine Encephalitis, West Nile Virus and other pathogens. Once they diagnose certain mosquitoes with the disease, they go back to the area they found them and spray pesticides. Debboun said that the crews only spray when it is necessary, in order to keep the ecosystem healthy, it is strictly science-based and backed by data.

Another way that the vector control district seeks to help residents is through education. They often send crews around town, to schools and outdoor games to hand out informational pamphlets to parents. Not only that, but the vector control district is also seeking out more options to keep the pesky population down.

“We have pamphlets that we give people we talk to them, we try to educate the community and make them aware so they can be part of the solution with us,” Debboun said.

One way they are doing this is through a biotech company, Oxitec, that created genetically engineered (GE) mosquitoes. The male GE mosquitoes from Oxitec have been engineered with a self-limiting gene, and this gene infects wild female mosquitoes to prevent them from reproducing female offspring. This leaves only male mosquitoes in the gene pool, according to Gorman. Female mosquitoes are targeted since they are the only ones that bite, and therefore capable of transmitting diseases. The engineered males will only mate with Aedes aegypti females, and do not leave an environmental footprint, according to Gorman. The release of these mosquitoes is supposed to reduce the natural population of the invasive mosquito, which are known to carry diseases such as dengue, chikungunya, Zika, yellow fever and others.

The GE mosquitoes also have a fluorescent marker gene which enables them to be distinguished from invasive mosquitoes for effective monitoring. The self-limiting gene cannot establish itself in the ecosystem long term and does not impact non-target species, according to Gorman.

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