Effects of salinity on the larvae of some Afrotropical anopheline mosquitoes.

Laboratory experiments showed that the larvae of some freshwater-breeding Afrotropical anopheline species exhibit various degrees of tolerance to 25% sea-water. At 24 degrees C, survival rates from egg to fourth instar larva were significantly less in salt-water than in freshwater for four species: 39.5% versus 55.4% for Anopheles tenebrosus Dönitz, 31.9% versus 86.2% for An. mousinhoi De Meillon & Pereira, 3.5% versus 67.9% for An. pharoensis Theobald and 3.9% versus 41.9% for An. quadriannulatus (Theobald). Conversely, An. merus Dönitz showed a significantly better survival rate of 46.4% in 25% sea-water compared with 15.5% in freshwater. Simulated winter conditions did not significantly change these differential survival rates of An. merus. Effects of salinity on the anal papillae of third instar larvae are discussed.