A Question of Preference: Investigating Host-Seeking Behaviour in Argentinian Aedes aegypti Mosquitoes

Abstract

The yellow fever mosquito Aedes aegypti is one of the primary vectors of human disease. Its global success as a vector hinges on the invasive nominate subspecies (Aedes aegypti aegypti) that specializes on human hosts and has spread around the world. The invasive Ae. aegypti aegypti lineage evolved in West Africa ~5,000 years ago from the ancestral African subspecies (Aedes aegypti formosus), which remains largely an animal-generalist and is confined to sub-Saharan Africa. Recent whole‑genome sequences of Ae. aegypti in varying regions around the globe uncovered a genetically unique population in Argentina that retains genetic signatures characteristic of the ancestral African Ae. aegypti formosus populations. So far, it is the only such Ae. aegypti population outside of Africa that has this genetic make up. Whether these Argentinian populations also retain animal-generalist host‑seeking behaviour is unknown. We quantified host-preference in three Argentinian Ae. aegypti populations using a two‑port olfactometer with a human hand and guinea pig as competing stimuli. We benchmarked these strains against a strongly human-preferring Ae. aegypti aegypti laboratory strain from Orlando, Florida (ORL), and an African generalist Ae. aegypti formosus strain from Uganda (ZIK). Our results showed ORL having the strongest human preference and ZIK showing only weak human preference to no preference. All three Argentinian strains slightly preferred human odor, with mean preference indices ranging between that of ORL and ZIK. In contrast, response rates of all three Argentinian strains were consistently lower than ORL and more similar to ZIK. Our results suggest that Argentinian Ae. aegypti populations combine weak human odor attraction with relatively low assay engagement for a behavioural phenotype consistent with heterogenous specialization on human hosts.