Mosquitoes (Diptera: Culicidae) Breeding in Brackish Water: Female Ovipositional Preferences or Larval Survival?

Four species of mosquitoes were abundant in concrete reservoir tanks containing brackish water that ranged from 16 to 39% sea water. The ability of the larvae to survive in various salinities was compared for each species with the ovipositional preferences of the adult females to determine whether the 2 traits were correlated. Southern house mosquito, Culex quinquefasciatus Say, normally was not present in the tanks but survived well in salinities up to 25% sea water. However, gravid females almost always oviposited in fresh water. Culex sitiens Weidemann larvae survived best in saline water (66% sea water), but opposition was greatest in 28% sea water; both larval survival and the frequency of opposition were low in fresh water. Culex sinaiticus Kirkpatrick survived salinities up to 50% sea water, but the females refused to blood-feed; therefore, their ovipositional preferences were not tested. Larvae of Anopheles stephensi Liston and An. culicifacies Giles survived best in fresh water, but some An. stephensi were able to tolerate up to 50% sea water. The females had a similar ovipositional preference for fresh water. The preferred salinity for oviposition did not correspond with larval survival for Cx. quinquefasciatus and Cx. sitiens, but did compare well in An. stephensi and An. culicifacies.