Tolerance of disease‐vector mosquitoes to brackish water and their osmoregulatory ability

Abstract

Salinity tolerance is an important trait that governs the ecology of disease‐vector mosquitoes by determining their choice of larval habitat, and consequently their ecological and geographical distribution. Here, we used laboratory strains to determine the osmotic responses of larvae of obligate freshwater disease‐vector mosquitoes (Aedes aegypti, Aedes albopictus, Anopheles coluzzii, An. gambiae, Culex pipiens, and Cx. quinquefasciatus) and assessed their relationship with salinity tolerance. First, we analyzed the acute dose–mortality response of fourth‐instar larvae to salinity; then, we measured their hemolymph osmolality after 24‐h exposure to varying salinities. We found that Ae. albopictus was the most tolerant species, followed by An. coluzzii, Ae. aegypti, Cx. quinquefasciatus, and An. gambiae, in decreasing order. Cx. pipiens was the least tolerant species. All mosquitoes were hyper‐iso‐osmoregulators, but with species‐specific differences. Specifically, hemolymph osmolality in deionized water varied among species, and Cx. pipiens and the two Aedes species showed the lowest and highest osmolality. Although all species were osmoconformers at higher salinity values, hemolymph osmolality approached environmental osmolality more rapidly in species of the Culex genus, compared with Aedes species where it increased slowly. Moreover, hemolymph osmolality in deionized water was significantly correlated with tolerance to salinity across species. This could allow predicting the salinity tolerance of untested species on the basis of their osmoregulatory ability. However, this correlation disappeared when considering the hemolymph osmolality of larvae exposed to salinities higher than deionized water.

Ecological plasticity to ions concentration determines genetic response and dominance of Anopheles coluzzii larvae in urban coastal habitats of Central Africa

“…coluzzii is also more abundant than An. gambiae in coastal habitats due to its higher tolerance to salinity concentrations 34 , 52 . However, it is not known whether ammonia and salinity tolerance share a common physiological mechanism origin in this malaria mosquito.…”

Transcriptomic, proteomic and ultrastructural studies on salinity-tolerant Aedes aegypti in the context of rising sea levels and arboviral disease epidemiology

“…Fourth instar larvae (L4) of FW Ae. aegypti are able to maintain haemolymph osmolarity (~ 300 mOsm equivalent to ~ 10 ppt salt or ~ 30% sea water) [ 29 ] for a short period by increasing amino acid and ion concentrations up to an external salinity of ~ 30% sea water [ 35 – 37 ]. Genomic changes and physiological mechanisms that permit FW Ae.…”

Insecticide Resistance Profile of Anopheles gambiae Mosquitoes: A Study of a Residential and Industrial Breeding Sites in Kano Metropolis, Nigeria

“…9 Ecologically, A melas, A merus, and A bwambae are salt-tolerant and are described as saltwater or mineral water species, while the others are obligate freshwater species. 10 Their public health importance stems from their high anthrophilicity and potential to exploit and adapt to diverse environmental conditions occasioned by human activities -directly or indirectly. 7 This is an indication that they are able to evolve different mechanisms for survival under different environmental conditions defined by various physicochemical parameters.…”