Sioux Falls health officials who monitor insect traps found a species of mosquito new to South Dakota near Sioux Falls.

Denise VanRoekel, the Health Program Coordinator with the Sioux Falls Health Department, reported that a “different looking” mosquito was found in one of the traps and asked for additional confirmation from South Dakota Cooperative Extension Entomologist Mike Catangui on September 21.

“She alerted me, and I looked at the specimen, then recommended daytime trapping, which produced three more specimens on September 23,” Catangui said. “I recommended daytime trapping because I suspected this mosquito might be a daytime biter.”

The mosquito species that was found is Aedes japonicus, a known potential vector of West Nile virus and several forms of encephalitis. Catangui said this species is more commonly known as the Japanese rock pool mosquito or the Asian bush mosquito. The species is common in several Asian countries including Japan, Korea, and Taiwan.

“This species is a daytime biting mosquito, and if we find it has established itself here, it may lead to changes in control measures used in the state,” said Catangui.

It was first found in the U.S. in 1998 in two sites in New York and in one site in New Jersey. In 2007, it was first found in Minnesota, Catangui said, and established populations were reported in several Minnesota counties from the Iowa border to the Twin Cities.

The mosquito most commonly reproduces in small pools of stagnant water. It can pose a longer term threat than some species because its eggs will overwinter. Its eggs can remain in artificial containers such as tires, buckets, or birdbaths, and the fact these possible reproduction areas are more often found closer to population centers is another reason the capture of this insect could be significant, said Catangui.

“Finding it now will give us a chance to refine our control approaches and prepare our methods, including daytime spraying, to control this mosquito,” Catangui said. “We are encouraging all agencies that trap mosquitoes to continue monitoring for as long as possible this fall so we can continue to gather information.”

Catangui said that while Aedes japonicus is a known vector for disease, it has not caused significant increases in West Nile virus or other illnesses in states where populations of the insect are now established.

“It does not appear to be very common, and credit goes to City of Sioux Falls Vector Control Division’s work on this effort to maintain surveillance on mosquitoes,” Catangui said. “We are in luck, so to speak, because we found it now and can use the time winter allows to continue study and to prepare for possible changes in both surveillance and control measures in 2010.”

Catangui also recommended that landowners check their property for any container that might hold water and to discard the water, since the mosquitoes’ eggs can survive over the winter.

Lon Kightlinger, state epidemiologist with the South Dakota Department of Health, said the finding has significance.

“The find shows that our surveillance system works, but it reminds us that we must keep alert and be ready to respond,” Kightlinger said. “It shows we have a robust system in Sioux Falls and in South Dakota, and the ongoing need for vigilance. We have good, competent control measures in place and we need to maintain them.”

For more information on recent South Dakota insect news, visit Catangui’s entomology Web site at this link: http://plantsci.sdstate.edu/ent/. For more information on South Dakota’s insect control measures, visit the Department of Health’s West Nile virus page at this link: http://doh.sd.gov/WestNile/Default.aspx.