Oxygen as a hatching cue for Aedes aegypti: a comparative study investigating differences in hatching behavior among generalist and domestic subspecies

Abstract

Aedes aegypti is the primary vector of dengue fever, yellow fever, chikungunya, and Zika. These diseases are significant global concerns, with nearly 100 million annual cases of dengue fever alone. Aedes aegypti is such a successful vector of these diseases because it targets humans and human-dominated habitats. Dissolved oxygen is an important hatching cue for Aedes aegypti eggs because, if sufficiently low, it signals that there is ample bacteria present for larvae to feed on after hatching. However, human-stored water is relatively clean, and thus contains higher levels of dissolved oxygen than water that collects in a natural environment. We used three different hatching, humidity, and oviposition experiments to investigate how Aedes aegypti aegypti’s egg hatching behavior has evolved relative to the ancestral generalist subspecies, Aedes aegypti formosus. We focused on dissolved oxygen level, genetics, maternal and egg humidity, and oviposition patterning strategies. These experiments aimed to increase our understanding of how Aedes aegypti has evolved to better exploit human-dominated habitats. We found that the domestic aegypti does in fact appear to have altered its egg hatching behavior in order to exploit human-dominated habitats by hatching in water with high dissolved oxygen levels. We also found that maternal humidity plays an influential role in hatching behavior, and that domestic mothers may be more variable in their oviposition pattern strategies compared to generalist mothers. These results provide important information for public health interventions, highlighting the importance of improving water-storage techniques. The humidity data also calls for us to expect an increase in the range of Aedes aegypti and the diseases that it vectors.