The micro enzyme-linked immunosorbent assay (ELISA) was used to specifically identify bloodmeal sources of Aedes triseriatus Say and Aedes vexans Meigen collected at a site endemic for La Crosse (LAC) encephalitis virus. Deer were the source of 65% of Ae. triseriatus and 94% of Aedes vexans bloodmeals, respectively. Chipmunks and tree squirrels, which are considered to be the major vertebrate amplifying hosts of LAC virus, were the sources of 8% and 16%, respectively, of the bloodmeals of Ae. triseriatus, the vector of LAC virus. The relatively small proportion of vector bloodmeals taken from the amplifying hosts raises further doubts as to the significance of vertebrate amplification in perpetutation of La Crosse virus in nature, i.e. whether vertebrate amplification alone is sufficient to make up for the shortfall of virus infection that occurs during vertical transmission.
current address: Walter Reed Army Institute of Research, Department of Entomology, Washington, D.C. 20012.