Blood-Feeding Patterns of Culiseta Melanura (Diptera: Culicidae) and Associated Sylvan Mosquitoes in Southeastern Massachusetts Eastern Equine Encephalitis Enzootic Foci1

Abstract

The capillary precipitin technique was used to examine the host utilization pattern of Culiseta melanura in southeastern Massachusetts EEE enzootic foci. Resting boxes were used to collect 1792 blood-engorged females in sites at the perimeters of historically enzootic swamps, and 1563 in upland areas near horse corrals and human dwellings. Avian (primarily passerine) blood was identified in 98.7% of the meals at the perimeter during 1977, and in 98.8% outside the swamps in 1978. Nonavian single blood meals included: dog (0.22%); rabbit (0.3%); cat (0.6%); snake (0.06%); other reptiles (0.06%); and amphibians (0.03%). During 1978, 11.5% of the meals from a single perimeter site were mixed, frequently including rabbits and passerine birds. The general trend in both areas was toward almost exclusive feeding on passerines early in the season, with a gradual increase in feeding on other birds and, to a much lesser extent, mammals, reptiles, and amphibians later in the summer. Preliminary experiments showing greater fecundity with blood meals from chickens rather than rabbits indicate physiological as well as behavioral adaptations directed toward a successful relationship with avian hosts. Lack of feeding on EEE-susceptible mammals suggests that the role of Cs. melanura in the disease is limited to the avian cycle. Identifications of blood meals from other mosquito species point to Coquillettidia perturbans, Aedes canadensis, and Ae. vexans as possible vectors of EEE to horses and humans.