Searching for potential bridge vectors in the mosquito community of equestrian facilities

VEZZANI D; CARDO MV

La Plata

Congreso; II Congreso de la Sociedad Latinoamericana de Ecología de Vectores; 2022

SOVE

Arboviral encephalitides are a growing global concern. In temperate Argentina, St. Louis Encephalitis and West Nile viruses have been isolated from birds and mosquitoes, along with sporadic human cases. Both diseases present similar transmission dynamics, with an enzootic cycle maintained among wild birds and epizootic / epidemic cycles which may affect horses and humans among a wide range of mammals. While the mosquitoes grouped in the Culex pipiens L. complex have been incriminated as cosmopolitan vectors of these diseases, the role of other coexisting species is unclear and local cycles are poorly understood. In this context, mosquito blood feeding patterns are a key component in the dynamics of disease transmission, as they represent the nexus between birds and mammals. For most of the mosquito species in Buenos Aires Province, there is no information on their feeding habits. Our objective was to characterize blood feeding sources of usually ignored mosquito species inhabiting equestrian facilities in temperate Argentina, to identify potential bridge vectors. Adult resting mosquitoes were collected monthly in urban and rural fields from December 2018 to April 2019 with a battery-powered aspirator. Engorged females were identified to species with taxonomic keys and the blood source for each specimen was identified using molecular techniques. Laboratory work included mithocondrial DNA extraction, PCR amplification of a conserved fragment of the COI gene, sequencing of the amplified fragment and comparison with available sequences in GenBank. A total of 73 blood meal sources of female mosquitoes from 8 species were identified: Aedes albifasciatus (4 specimens), Ae. crinifer (23), Cx. apicinus (14), Cx. chidesteri (2), Cx. dolosus (7), Cx. eduardoi (9), Cx. lahillei (1) and Cx. maxi (13). From them, 13 vertebrate species were recognized as hosts, five of them were mammals (cow Bos taurus, dog Canis lupus, horse Equus caballus, brown hare Lepus europaeus, sheep Ovis aries) and the remaining were birds (chalk-browed mockingbird Mimus saturninus, monk parakeet Myiopsitta monachus, house sparrow Passer domesticus, spot-winged pigeon Patagioenas maculosa, picazuro pigeon Patagioenas picazuro, whistling heron Syrigma sibilatrix, house wren Troglodytes aedon, rufous-bellied thrush Turdus rufiventris). Four mosquito species (Cx. apicinus, Cx. chidesteri, Cx. dolosus and Cx. eduardoi) used both avian and mammalian hosts, and presented at least one feed on horse. Therefore, these species represent a potential risk of pathogen transmission from avian enzootic cycles to horse epizootics.