Development of Aedes aegypti (Diptera: Culicidae) mosquito larvae in high ammonia sewage in septic tanks causes alterations in ammonia excretion, ammonia transporter expression, and osmoregulation

Abstract

Larvae of the disease vector mosquito, Aedes aegypti (L.) readily develop in ammonia rich sewage in the British Virgin Islands. To understand how the larvae survive in ammonia levels that are lethal to most animals, an examination of ammonia excretory physiology in larvae collected from septic-water and freshwater was carried out. A. aegypti larvae were found to be remarkably plastic in dealing with high external ammonia through the modulation of NH4+ excretion at the anal papillae, measured using the scanning ion-selective electrode technique (SIET), and NH4+ secretion in the primary urine by the Malpighian tubules when developing in septicwater. Ammonia transporters, Amt and Rh proteins, are expressed in ionoregulatory and excretory organs, with increases in Rh protein, Na+-K+-ATPase, and V-type-H+-ATPase expression observed in the Malpighian tubules, hindgut, and anal papillae in septic-water larvae. A comparative approach using laboratory A. aegypti larvae reared in high ammonia septic-water revealed similar responses to collected A. aegypti with regard to altered ammonia secretion and hemolymph ion composition. Results suggest that the observed alterations in excretory physiology of larvae developing in septic-water is a consequence of the high ammonia levels and that A. aegypti larvae may rely on ammonia transporting proteins coupled to active transport to survive in septic-water.

Biology and Behaviour of Aedes aegypti in the Human Environment: Opportunities for Vector Control of Arbovirus Transmission

“…The first evidences of septic tanks used as larval development sites come from Malaysia [ 176 ], Nigeria [ 177 ] and Colombia [ 178 ] where, in the city of Cali they represented the most productive Aaa larval habitat. These findings have been subsequently confirmed in other geographical areas [ 179 , 180 , 181 ]. Interestingly, larval habitat differences (rock pools vs. domestic containers), consistent with genetic differentiation indicated Aaa in Anguilla island “do not constitute a single panmictic population, but there are no large consistent differences to parallel the East African sylvan-domestic dichotomy” [ 182 ].…”

“…The importance of a sugar feeding habit, which is variously reported in its use by Aaa [ 63 , 64 , 66 , 70 , 71 ], should be determined in multiple geographic areas. Oviposition site selection behaviour may be far broader than thought: several reports exist of Aaa colonising septic tanks [ 176 , 177 , 178 , 179 , 180 , 181 ], but it is not clear if they only describe local and marginal situations or additional studies could confirm whether these organically rich water sources represent an important production site worldwide or only in certain environments/geographic areas.…”

Ammonium transporter expression in sperm of the disease vector Aedes aegypti mosquito influences male fertility

“…In the mosquito Aedes albopictus , Rh protein ( AalRh50 ) transcript is expressed at modest levels in ovary tissue of adult females and is unaltered following blood feeding ( 15 ). Given our previous characterizations of AMT proteins (AeAmt1 and AeAmt2) in A. aegypti larvae which are expressed in organs important for ion and water balance and digestion ( 32 , 33 , 49 ), we speculated that AeAmt1 and AeAmt2 would play functionally similar roles in digestive and excretory organs in adults, particularly following ingestion of a protein-rich blood meal by females. To examine this hypothesis, we utilized immunohistological techniques with previously validated AeAmt antibodies ( 32 , 33 ).…”

Humidity – The overlooked variable in the thermal biology of mosquito‐borne disease

“…The relationship between organismal fitness and optimal hydroregulation is complex, with significant costs to fitness (e.g., decreased survival and reproduction) occurring when organisms become dehydrated (Anderson & Andrade, 2017; Mitchell & Bergmann, 2016) or overhydrated (Chown & Nicolson, 2004). Insects have a suite of adaptations to conserve water, like physiological changes in skin or cuticular permeability (Rajpurohit et al, 2008; Wu & Wright, 2015), differential regulation of urine and faeces production (Durant et al, 2021; Durant & Donini, 2019; Lajevardi et al, 2021; Weihrauch et al, 2012), and behavioural changes in activity (Kühnholz & Seeley, 1997; Ostwald et al, 2016). Insects also can mitigate water loss by regulating water intake via changes in water utilization, food sources and selection of specific habitats (Benoit, 2010; Bezerra Da Silva et al, 2019; Hagan et al, 2018)).…”