Mosquito Control in the Aquatic Environment with Monomolecular Organic Surface Films.

The lifestyle of immature forms of the mosquito in water is highly dependent upon the properties of the air-water interface. Nonionic monomolecular organic films, which reduce surface tension and increase the wettability of breathing structures, produced high cumulative mortalities and mortality rates in fourth-instar larvae of Anopheles quadrimaculatus. These results were demonstrated both in the laboratory and in field studies. Effective surface films were maintained for at least 24 h with an initial application of only 0.04 ml of film-forming liquid per square meter of water surface. Two of the compounds, isostearyl alcohol 2 oxyethylene groups and sorbitan monooleate, were 100 effective against these larvae in the field, each experiment involving about 5,000 organisms. Although laboratory research indicated that larvae of Aedes aegypti were not killed by the surface films studied, their development rate was greatly retarded. Three of the surface films caused 100 cumulative mortalities to pupae and emerging adults of this species. The mechanisms by which the film-induced surface affects the life cycle of the mosquito are discussed. Optimum properties of film-forming materials for practical mosquito-control applications are itemized and related to chemical structural considerations. The applicability and limitations of this approach to mosquito control are reviewed. Author