Dual‐host choice experiments reveal inconsistent seasonal blood‐feeding preference in Argentinean <i>Culex quinquefasciatus</i> populations

Mosquitoes of the genus Culex are important vectors of St. Louis encephalitis (SLEV) and West Nile (WNV) viruses, and their host-feeding patterns strongly influence transmission dynamics by shaping contact rates between avian and mammalian hosts. In the United States, several Culex species exhibit seasonal shifts in host use, feeding primarily on birds during summer and increasing mammalian feeding in autumn. This shift coincides with seasonal peaks in SLEV and WNV incidence, suggesting that changes in mosquito feeding behaviour may trigger viral spillover to mammals. However, no experimental study has evaluated whether such seasonal patterns occur in South American populations. In this study, it was tested whether an Argentinean population of Culex quinquefasciatus shows seasonal variation in feeding preference under controlled laboratory conditions. Starved females were simultaneously offered a chick (Gallus gallus) and mouse (Mus musculus) in dual-choice assays conducted under summer and autumn conditions, both representing a combination of simulated temperature and photoperiod regimes. Blood-meal sources were determined using multiplex polymerase chain reaction (PCR), and feeding proportions were analysed using a Bayesian multinomial logistic regression. Mosquitoes fed on both hosts in both seasons with a high proportion of mixed blood meals, with no consistent evidence of a seasonal host shift. Substantial variation among replicates indicated high intra-population heterogeneity. Overall, Cx. quinquefasciatus exhibited a generalist and plastic feeding strategy rather than a defined seasonal pattern. Although no seasonal shift was detected, the generalist behaviour supports its potential role as a bridge vector of arboviruses in South America.