West Nile virus-carrying mosquito species are expanding in South Dakota, but money to battle the carriers has dwindled, local officials say.

Lon Van Deusen, Rapid City Parks Division manager, said a new species of mosquito capable of carrying West Nile virus and LaCrosse encephalitis virus that can infect humans was found within the state.

"The Japanese rock pool mosqito has been identified in South Dakota," he said.

Yet, its discovery and possible health-risk issue hasn't generated any additional funds for mosquito abatement programs in Pennington County or Rapid City.

With Rapid City and Pennington County described last February by state epidemiologist Lon Kightlinger as the epicenter of West Nile virus in the Dakotas, officials here have already started their mosquito control programs.

Scott Guffey, Pennington County Weed & Pest supervisor, said his people began two weeks ago treating standing water in the road ditches for mosquito larvae and surveying known mosquito sites. Using a biologically-based briquette, the environmentally safe insecticide doesn't hurt fish and other water organisms but targets mosquitoes at the larval stage.

"We'll check those areas again in the next three weeks," Guffey said of the maturing insects.

This year, his office received $13,500 from the state, less than last year, he said.

However, the county still has the same mosquito abatement program in place. The 2009 budget will provide for only one seasonal person and the program's operational costs, including gas, maintenance and supplies.

Guffey said the crews will put up their adult mosquito traps in the coming weeks. Once the population of Aedes vexans and Culex tarsalis mosquitoes go up, it will trigger spraying on selected roads and wetlands in Rapid Valley and beyond, Guffey said.

"We don't go out spraying for the sake of spraying," he said.

Van Deusen said the city received $12,500 from the state for mosquito control.

"But we will continue with the same program as in the past," Van Deusen said.

On Monday, park workers fogged the city's ball parks. The five-member team also will start its larvae-sighting program where there are wet fields, meadows and other areas of standing water. Depending on the weather, the staff will do more spraying later in the week.

"The larvae-spraying program has been very effective as well in the treatment of the wetland areas and standing water," Van Deusen said.

Last year, the city added residual spraying - an application of insecticide on adult mosquitoes. It will be part of this year's program as well.

"I'm not anticipating any cutbacks," Van Deusen said. "Our administration has said to carry on as in the past. It's a serious enough health issue that they aren't worried about the finances," Van Deusen said.

South Dakota has four times the national average of West Nile incidences, he said.

In spite of dwindling budgets, what area people do in their own backyards can make a huge difference.

"There's more standing water than we've had in recent years … It's the kind of habitat that tarsalis mosquitoes, a carrier vector, likes to live," Van Deusen said.

He suggested that people carefully examine their backyards for places where water will collect such as old tires, plugged-up roof gutters, cans and even cemetery vases.

"People should regularly change the water in bird baths and kids' pools," he said.

Contact Jomay Steen at 394-8418 or jomay.steen@rapidcityjournal.com.