Molecular Identification of Blood-Meal Sources in Culiseta Melanura and Culiseta Morsitans From an Endemic Focus of Eastern Equine Encephalitis Virus in New York

Abstract

Eastern equine encephalitis (EEE) virus perpetuates in an enzootic cycle involving ornithophilic mosquito vectors, principally Culiseta melanura (Coquillett) and avian amplification hosts. To better understand the role of Cs. melanura and Culiseta morsitans (Theobald) in the epizootiology of EEE virus, we collected blood-fed mosquitoes between 31 May and 15 October 2004 at two sites associated with an EEE virus focus in central New York and identified the source of vertebrate blood by nucleotide sequencing of polymerase chain reaction (PCR) products of the cytochrome b gene. Analysis of 484 Cs. melanura and 122 Cs. morsitans revealed that 94.2% and 86.9%, respectively, acquired blood solely from avian hosts. Blood meals derived exclusively from mammals were detected in 0.8% of Cs. melanura and 1.6% of Cs. morsitans. Individual mosquitoes containing mixed-blood meals from both avian and mammalian hosts were also detected in 5.0% of Cs. melanura and 11.5% of Cs. morsitans. Wood thrush constituted the most common vertebrate host for Cs. melanura (23.6%) and Cs. morsitans (30.9%), followed by American robin, song sparrow, ovenbird, red-eyed vireo, and common yellowthroat. Mammalian-derived blood meals were identified as white-tailed deer, horse, domestic cat, and eastern pipistrelle bat. There were three isolations of EEE virus from Cs. melanura and one from Cs. morsitans. These results suggest that wood thrush and a few other passerine birds may play key roles in supporting EEE virus transmission in the northeast and possibly throughout the geographic range of EEE in North America. The frequency of mammalian feedings also suggests that Cs. melanura and Cs. morsitans may play a role in the transmission of EEE virus to equines, in addition to maintaining enzootic transmission among avian hosts. We report the first isolation of arboviruses from mosquito vectors concomitant with the identifications of their blood meal sources.

Flavivirus Infections of Bats: Potential Role in Zika Virus Ecology

“…Evidence exists for mosquitoes feeding on bats, although the frequency with which this happens in the field is not well understood and difficult to study. In a study focused on the blood hosts of two species of Culiseta mosquitoes in New York with respect to transmission of eastern equine encephalitis virus, Molaei and others 40 catalogued one Culiseta morsitans Theobald blood meal from an eastern pipistrelle (Pipistrellus subflavus) bat. This observation comprised less than 1% of the total number of blood meals analyzed from this mosquito species.…”

Host compatibility rather than vector–host-encounter rate determines the host range of avian Plasmodium parasites

“…Mosquito-feeding networks may also be compartmentalized [17], with certain vector species using a distinct subset of available host species [14,[18][19][20][21]. For instance, in the northeastern United States, Culex restuans, Culex pipiens, and Culiseta melanura obtain blood meals from birds, while the sympatric Aedes vexans, Ochlerotatus and Anopheles species rely primarily on mammals for blood meals [18,22,23].…”

Competency of Reptiles and Amphibians for Eastern Equine Encephalitis Virus

“…melanura may also occasionally act as a bridge vector and as the primary enzootic vector. 6 Mammals are generally considered dead-end hosts for the virus, though small mammals have recently been implicated as potential amplification hosts for North and South American strains of EEEV. 7 The EEEV circulates year round in Florida, but its transmission is seasonal outside of this state.…”