Strategies for the emergency control of arboviral epidemics in New Orleans.

A study was initiated to evaluate the effectiveness of aerial ULV spraying for the control of Aedes aegypti and Culex quinquefasciatus as an emergency antiepidemic measure against dengue fever and St. Louis encephalitis, respectively. Malathion was aerially applied at 219 ml/ha over 344 ha area of the Ninth Ward in New Orleans. Laboratory susceptibility tests and field-cage exposures indicated that the target populations were susceptible to malathion and that acceptable coverage of the study area occurred. Two consecutive aerial applications decreased the relative abundance and ovipositional activity of adult mosquitoes. However, suppression was transient and, in the event of an epidemic, multiple treatments may be required to decrease vector abundance below the threshold levels required for the spread of virus to the human populations.