Overabundant single-host settings as field labs to assess blood meal patterns of mosquitoes.

Abstract

Blood meal patterns of mosquitoes (Diptera: Culicidae) are strongly influenced by host availability. However, the role of community composition and abundance of vertebrate hosts in determining such patterns is still unclear. Here, we analysed the blood meal sources of field-collected mosquitoes in settings with a permanent overabundance of a specific vertebrate species. Mosquitoes were collected using a battery-powered handheld aspirator every 2 months between November 2021 and April 2022 in temperate Argentina. Blood-engorged mosquitoes were collected at 11 sites corresponding to five types of settings: two cattle fields, one rabbit breeding farm, three chicken farms, two dog boarding facilities, and three geriatric hospitals, characterised by the permanent overabundance of cows, rabbits, chickens, dogs, and humans, respectively. Blood meal analysis was performed via polymerase chain reaction (PCR) and sequencing. A principal component analysis (PCA) was performed in which variables were pairs comprising an engorged mosquito species and the host species it fed on. A total of 242 blood meals from Aedes (3 species), Culex (4), Isostomyia (1) and Psorophora (1) were identified. Among these, five mammals and 12 avian species were identified as hosts. Overall, 79% of the blood meals were taken from the overabundant host, ranging from 67% to 99% in all settings except for geriatric hospitals (7%). The proportion of feeds taken on the overabundant host was lowest for Culex quinquefasciatus Say (0.67, N = 119), Cx. pipiens molestus Forskal (0.5, N = 18) and the hybrid between the two (0.5, N = 2), and highest for Aedes aegypti Linnaeus (1, N = 2), Ae. albifasciatus Macquart (1, N = 3), Ae. crinifer Theobald (1, N = 46), Cx. eduardoi Casal & García (0.9, N = 10), Isostomyia paranensis Brèthes (1, N = 20) and Psorophora ferox Humboldt (1, N = 21). By fixing host abundance in preselected settings, we propose a field design that overcomes the difficulties of estimating host community composition. This approach aids in achieving a clearer understanding of mosquito feeding patterns and their implications for arbovirus disease transmission.