Seasonal Prevalence of Mosquitoes Collected from Light Trapsin Korea (1999-2000)

The Entomology Section, 5th Medical Detachment (MED DET) (Preventive Medicine) (PM), in coordination with the Department of Public Works (DPW), 8th US Army-Engineers, conducted annual mosquito surveillance programs at US military installations in the Republic of Korea (ROK) in accordance with Army Regulation (AR) 40-5 (Department of the Army, 1990). Mosquito populations and species distributions throughout the ROK, especially vector species, is of primary importance to US and ROK militaries since each expends substantial amounts of manpower and pesticides for mosquito control to reduce potential health risks to military personnel. Currently, the primary mosquito-borne disease of greatest concern in the ROK is malaria. Malaria was regarded as officially eradicated in the ROK, until its reintroduction in 1993. Since the first case of vivax malaria was reported in 1993 (Chai et al., 1994), malaria continued to increase in the northwestern area of Gyeonggi Province along the demilitarized zone (DMZ) (Lee et al., 1998, 2002). Most US military installations and training sites are located adjacent to rice paddies that are not under the jurisdiction of the US or ROK Armies. These mosquito habitats include rice paddies, parsley fields, ground pools, sewage and drainage ditches, culverts and irrigation ponds that are located mainly off the military installations. These habitats infrequently occur on military installations except during the rainy season. In addition to larval habitats, many of the rural installations are near swine and dairy farms that attract numerous mosquitoes. Yu and Kim (1989) provided valuable data on some biological agents used to control larvae. However, the use of biological and chemical agents by the Korean public and Public Health officials to control larvae is limited. Therefore, the development of an effective means for controlling adult mosquitoes on military installations is the primary focus of the US military mosquito control program. The 5th MED DET instituted a “Trap Index” that establishes a baseline for initiating/conducting pesticide applications when numbers of female vector mosquitoes captured in a New Jersey (NJ) light traps exceed the threshold (Yi et al., 1988). Although this method is associated with many inaccuracies, it serves as a valuable operational tool to reduce pesticide usage and environmental exposure. Pest control personnel (DPW) at selected US installations operate the NJ light traps, collect captured insects, and forward them by postal service to the 5th MED DET for identification. Based on population densities of vector/nuisance species, the 5th MED DET recommends whether pesticide application is warranted within two days after the samples are received. The purpose of this paper is to present additional scientific data that increases our current knowledge of the seasonal abundance and geographical distribution of selected mosquito species captured at US military installations in the ROK. The recent outbreak of malaria in Korea is a reminder of the importance of maintaining this historical record of vector populations and seasonal trends.