Host preference of mosquitoes (Diptera: Culicidae) collected in Germany

Next to vector competence, blood host preference is a major factor determining the risk pathogen transmission by mosquitoes between different groups of vertebrates.
We analysed blood-fed mosquito females, collected throughout Germany from 2016 to 2022, for their bloodmeal origin. Two PCR protocols were used: if DNA amplification and sequencing of a conserved 16S rDNA region did not yield results, the samples were subjected to COI barcoding. The obtained sequences were aligned with GenBank, and only results with a minimum identity of 97% were accepted.
Of 485 mosquito specimens processed, 355 belonging to 27 species/species groups produced interpretable results. Forty-two vertebrate species were identified as hosts, including 22 mammalian, 17 avian, 2 reptilian and 1 amphibian species. Except for Culex territans, which exclusively fed on reptiles and amphibians, all mosquito species had fed on mammals. Five mosquito taxa could be linked to both avian and human blood hosts and 16 taxa to both non-human mammalian and human hosts.
The study demonstrates a surprisingly broad host acceptance. Both Cx. pipiens biotype pipiens and Culiseta morsitans/fumipennis, which are commonly considered ornithophilic, were shown to have fed on mammals, including humans. The findings suggest that host preference is generally less pronounced and bridge vectors between animals, in particular birds, and humans, may occur more frequently and widely distributed than previously discussed.