1 Mosquito 4 Viruses: Characterization of Aedes aegypti populations within Ghana: correlations between habitat, morphology, and behavior

Abstract

The primary vector for transmission of Yellow Fever, Chikungunya, Dengue Fever, and Zika viruses is the Aedes aegypti mosquito. This species exists in two forms—Aedes aegypti formosus (Aaf), an ecologically variable form found primarily in sub-Saharan Africa, and Aedes aegypti aegypti (Aaa), a human specialist found globally in tropical and subtropical regions. The two subspecies show mean differences in morphology, but there is substantial overlap, and they can only reliably be distinguished using genetics. To date, research conducted in Kenya, Senegal, Tanzania, and Cameroon has shed light on Aedes aegypti populations based on geography, body coloration, and genetic makeup. However, little is known about the morphology and host preference of Aedes aegypti mosquitoes across most of West Africa. The goal of this project was to characterize morphological and behavioral variation among Aedes aegypti populations in Ghana that may affect their ability to transmit human disease. Live Ae. aegypti eggs were collected in the field and carried back to the McBride lab at Princeton University in the U.S. Morphology and behavior were then examined using a standard dissecting microscope and an olfactometer, respectively. The olfactometer allowed for measurements of preference for human vs. non-human odor. Results of this study suggest that there is significant morphological variation within the subspecies Aaf found in Ghana (p<0.008). On the topic of host preference, each colony preferred the non-human host as oppose to the human host in each trial, suggesting that with increased urbanization and vector density in West Africa, non-human reservoirs can pose a severe threat to humans if effective vector control measures are not prioritized.