Experimental test of the influence of aquatic macrophyte cover on the survival of Anopheles larvae.

Emergent or submergent macrophytes can enhance the survival of Anopheles larvae by providing favorable microhabitat and refuge from predation. The relationships among the amount of aquatic macrophyte cover, the density of Gambusia affinis, and survivorship of Anopheles freeborni larvae were tested experimentally. Larval survivorship was positively related to amount of plant cover and negatively related to Gambusia density. Larval survivorship was lowest in treatments with low plant cover and high fish density (0-15% survivorship) and highest in treatments with high plant cover and no fish (41-76% survivorship). Similar patterns of larval survivorship were found in enclosure experiments conducted at 3 sites, using 3 species of aquatic macrophytes (Potamogeton pectinatus, Myriophyllum aquaticum and M. spicatum).