Laboratory Oviposition Choice ofAedes aegypti(Diptera: Culicidae) From Kenya and Gabon: Effects of Conspecific Larvae, Salinity, Shading, and Microbiome

Abstract

The mosquito Aedes aegypti (L.) is the primary vector of several arboviruses. Mosquito control and surveillance are essential to restrict disease transmission, the effectiveness of which depends on our understanding of the mosquito’s behaviors, including oviposition. Previous studies have identified a variety of oviposition cues. However, most of these studies involved only Ae. aegypti outside of the species’ native range, Africa. Populations outside Africa differ in their genetics and some behaviors from their African counterparts, suggesting possibly different oviposition preferences. Within Africa, Ae. aegypti can be found in both ancestral forest habitats and domestic habitats. The African domestic populations may represent an intermediate state between the forest and the truly domesticated non-African populations. Comparing mosquitoes from these three habitats (African forest, African domestic, and non-African domestic) might provide insight into the evolution of oviposition behavior. In this study, I examined the oviposition choices of multiple Ae. aegypti colonies from all three habitats in laboratory settings. I applied a two-choice assay to test four oviposition cues: the preexistence of conspecific larvae, salinity, shading, and microbiome. A subset of African colonies showed similar oviposition choices as their non-African counterparts, whereas the rest show little response to the factors tested. Within the African colonies, oviposition choices of the domestic colonies were significantly different from the forest colonies in most experiments. Yet, their preferences were not always intermediate between that of mosquitoes from the other two habitats. Collectively, this study adds to our understanding of Ae. aegypti oviposition, especially in previously understudied African populations.

Larval breeding sites of the mosquito Aedes aegypti in forest and domestic habitats in Africa and the potential association with oviposition evolution

“…A recent study using the same Ae. aegypti colonies did find between-habitat ovipositional difference towards more extreme but unnatural conditions (Xia, 2021). The complexities regarding Ae.…”

Odour-mediated oviposition site selection in Aedes aegypti depends on aquatic stage and density

“…Oviposition site selection by gravid mosquitoes can be modulated by cues associated with the aquatic stages, in a species-, stage- and density-dependent manner [ 11 ]. Gravid mosquitoes generally avoid ovipositing in breeding sites in which the risk of con- and heterospecific competition and cannibalism/predation is high [ 12 – 19 ]. The manner by which individual species assess oviposition sites differs in accordance with species-specific breeding site requirements [ 2 , 6 , 11 , 20 ].…”

“…The manner by which individual species assess oviposition sites differs in accordance with species-specific breeding site requirements [ 2 , 6 , 11 , 20 ]. This is, therefore, dependent on the ability of gravid females to evaluate cues emanating from distinct conspecific aquatic stages, as these provide reliable signals of breeding site conditions [ 11 , 12 , 15 , 18 , 19 ]. Limitation in nutrient resources, regulated by, e.g., competition and the dynamic nature of mosquito-associated microbial communities, differentially affects oviposition site choice in a taxon-dependent manner [ 5 , 6 , 19 , 21 , 22 ].…”

Larval sites of the mosquito Aedes aegypti formosus in forest and domestic habitats in Africa and the potential association with oviposition evolution

“…A recent study using the same Ae. aegypti colonies did find ovipositional differences between forest and village colonies toward more extreme but unnatural conditions (Xia, 2021 ), highlighting the complexities of Ae. aegypti oviposition.…”

“…We used the fourth to the sixth generation in the oviposition assays. The detailed information of the mosquito colonies and protocols for maintaining these colonies are described in the Appendix S1 and Xia ( 2021 ).…”