Seasonal activity of La Crosse encephalitis vectors across different habitats

La Crosse encephalitis (LAC) is the predominant mosquito-borne disease amongst children in the United States. In the upper Mississippi River Valley, this disease is transmitted by two container-breeding mosquitoes, the eastern treehole mosquito (Ochlerotatus triseriatus (Say)) and the invasive Asian rockpool mosquito (Ochlerotatus japonicus (Theobald)). Seasonal LAC vector activity was examined along north and south-facing slopes in four different habitats representing different degrees and types of human disturbance. Adult mosquito activity was monitored using ovitraps built from black plastic pop bottles and opaque milk containers. Every week from late May through November 2010, mosquito eggs were collected and counted. The adult mosquitoes’ activity started on June 15th and ended October 17th irrespective of habitat. Population peaks occurred at the same time across locations. In most cases, there was no significant difference in mosquito oviposition activity between north-facing and south-facing slopes within a collecting locality. Transovarian transmission of LAC in O. japonicus is currently being tested.