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Stagnant pools at foreclosed homes could mean messy mosquito season

DOS PALOS — Mosquito season has begun. And with all the stagnant pools sitting around by foreclosed homes, this year could be a bad one, says Allan Inman, manager of the Merced County Mosquito Abatement District.

The season officially starts this month and will go into November. And lot more work goes into fighting these pesky insects — and the West Nile virus certain species carry — than many people think, Inman said.

His district and eight others from all over the Central Valley met in Dos Palos Thursday for a continued education program. There, they learned about the latest equipment, laws, study techniques and control methods available.

This is how abatement district workers stay certified. They must attend education sessions such as this one as the season begins in April and starts to draw to a close in October. “Do mosquitoes change? Not necessarily,” said Dennis Candito of the Sacramento mosquito control supply company Adapco, which helped host the program Thursday. “But do we need to learn new things? Yes.”

The program was held at Merced County’s Westside Depot, where the abatement district’s four planes for aerial spraying are stored.

Attendees got to watch demonstrations and learn about the extent of this county’s aerial program — which has more planes than any other district in the state, Inman said, “But we have over 180,000 acres of wetlands and dairies, the most ideal breading ground for vector West Nile virus in California.”

Two twin-engine planes it owns, the Cessna 02 and Beach Baron 58P, are able to fly right over Merced, Atwater and Livingston to spray city areas. These areas are attracting more mosquitoes because the insects are drawn to murky abandoned swimming pools.

Just spraying 1/3 of Merced by air with mosquito-killing droplets can significantly stifle West Nile, Inman said, adding there hasn’t been a human case recorded in Merced since 2005.This disease, which can cause severe flu-like symptoms, is the No. 1 mosquito-carried illness of concern right now, said Monica Patterson, a vector biologist from the Turlock Mosquito Abatement District.

Biologists are also focused on fighting the mosquito-carried diseases St. Louis Encephalitis and the Western equine encephalitis virus.

But before they can study the diseases and carrying species, they must capture the mosquitoes. Patterson and Jason Bakken, a biologist with the Merced County district, demonstrated several different traps.

One of them uses carbon dioxide as bait. The dry ice carbon dioxide within the trap simulates a person breathing in and out, which attracts mosquitoes, Bakken explained. A fan then blows the insects into netting, where they are trapped.

Then they can be assessed for disease.

Stacy Bearden, an entomologist with the San Joaquin County district, and Rhiannon Pintabona, a vector biologist with the East Side district in Modesto, showed off a Rapid Analyte Measure Platform (RAMP).

This provides an in-house way for mosquito abatement districts to test for West Nile quickly -- in about 90 minutes — instead of sending samples off to the state. “The quicker we know, the faster we can react as a district and (know) where the mosquitoes are coming from,” Bearden said.

Mosquitoes are collected, sorted, ground up and incubated as biologists look for indications of the virus. Districts that don’t have a RAMP must wait for the state to send back results in about four days.

Merced County does not yet have this feature, although it has the personnel and facility for it, Inman said: “We just don’t have the finances.”

Other types of equipment demonstrated Thursday showed methods of controlling levels of biological agents that kill either mosquito larvae or adults. It is critical to control these amounts so droplets aren’t wasted, put in the wrong place or applied against Environmental Protection Agency regulations, said Ben Goudie, control consultant for Clarke Mosquito Control, based in Illinois.

He demonstrated a machine that uses a probe to gather statistical analysis about the droplets within a fog of mosquito control agents.

Dan Ariaz, owner of Reno-based company Arro-Gun Spray Systems, showed off a diesel gator that shoots products known as “larvacide” into the water to kill mosquito larvae.

But this is only a small of a wide range of methods to fight or study mosquitoes. “Some of it has been around a while, but it’s always being improved,” Candito said.

Reporter Dhyana Levey can be reached at (209) 385-2472 or