To what extent does salt (NaCl) affect Anopheles gambiae sensu lato mosquito larvae survival?

Abstract

The effect of salt (NaCl) on Anopheles gambiae sensu lato (s.l.) mosquito larval breeding was ascertained under laboratory conditions. No larval mortality occurred when the Cl- concentrations were between 0.017 ppt (0.03 ppt salinity) and 7.371 ppt (13.25 ppt salinity). However, 9%, 24%, 73.5%, 91.5% and 99.5% larval mortality occurred at 10.828 ppt (19.49 ppt salinity), 16.069 ppt (28.95 ppt salinity), 18.739 ppt (33.77 ppt salinity), 32.587 ppt (58.82 ppt salinity) and 47.326 ppt (85.37 ppt salinity) NaCl concentrations respectively. The lower NaCl concentrations resulting in LC50, (lethal concentration for 50% larval mortality), LC90 (lethal concentration for 90% larval mortality), LC95 (lethal concentration for 95% larval mortality), and LC99 (lethal concentration for 99% larval mortality) were 23.12 ppt (41.19 ppt salinity), 24.91 ppt (44.42 ppt salinity), 27.76 ppt (49.56 ppt salinity) and 33.87 ppt (60.568 ppt salinity) respectively. The upper NaCl concentration resulting in LC50, LC90, LC95 and LC99 were 32.89 ppt (58.83 ppt salinity), 37.21 ppt (66.63 ppt salinity), 44.79 ppt (80.32 ppt salinity) and 63.76 ppt (114.55 ppt salinity) respectively. In conclusion, the level of water salinity may indicate the presence or absence of An. gambiae s.l. mosquito larvae and this information can be used for disease control purposes.