Blood feeding patterns of the Culex pipiens complex in equestrian land uses and their implications for arboviral encephalitis risk in temperate Argentina

MARÍA VICTORIA CARDO; ANÍBAL EDUARDO CARBAJO; CONSTANZA MOZZONI; MARLENE KLIGER; DARÍO VEZZANI

ZOONOSES AND PUBLIC HEALTH

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2022

1863-1959

Blood feeding patterns of mosquitoes are a key component in the dynamics of arboviralencephalitides transmission. In temperate Argentina, the members of the Culex pipienscomplex include Cx. pipiens molestus, Cx. quinquefasciatus and their hybrids. To characterizetheir blood feeding patterns, adult resting mosquitoes were collected monthly during thewarm season in urban and rural equestrian fields. The availability of birds and domesticmammals per site was characterized. The blood source and the complex member weresuccessfully identified for 89 specimens using PCR. Blood of 19 vertebrate species was isolatedincluding four mammals (most common feeds from dog, Canus lupus 19% of the blood meals;and horse, Equus caballus 18%) and 15 birds (picazuro pigeon, Patagioenas picazuro 11%;eared dove, Zenaida auriculata 10%; chicken, Gallus gallus 9%). The Forage Ratio (FR),calculated as the proportion of feeds taken from a given host species with respect to that hostavailability in the environment, suggested preference for dog by all members of the complex(FR  4.5). On the contrary, FR values suggested avoidance for horse by Cx. quinquefasciatusand the hybrid (FR  0.8), and a use proportional to its abundance by Cx. pipiens molestus (FR =1.1-1.2 in urban and rural sites, respectively). FR values suggesting preference were obtainedfor avian species of the orders Passeriformes (7 species in total) and Columbiformes (5) by allmembers of the complex (FR  3.3), whereas values for monk parakeet (Myiopsitta monachus,Psiitaciformes) suggested avoidance by Cx. quinquefasciatus in urban sites (FR= 0.4) and by Cx.pipiens molestus in rural sites (FR= 0.3) but not in urban sites (FR= 1.4). A mammal-bird index(MBI, from -1 all avian to +1 all mammalian blood meals) was calculated for each member ofthe complex and urbanization category. Values were negative for Cx. quinquefasciatus (MBIurban= -0.60, MBIrural = -0.33) and positive for Cx. pipiens molestus (MBIurban = 0.20, MBIrural = 0.60),indicating a higher proportion of feeds taken on birds and mammals, respectively, regardlessof the urbanization category. In temperate Argentina, the members of the Cx. pipiens complexfed both on horses and on birds, thus representing a real risk of transmission of arboviralencephalitides from avian enzootic cycles to horse epizootics.