Impact of naled (Dibrom 14) on the mosquito vectors of eastern equine encephalitis virus.
In central New York State, USA, aerial mosquito adulticide applications have been used in response to eastern equine encephalitis (EEE) outbreaks and have targeted the swamp habitats of the primary enzootic vector of EEE virus, Culiseta melanura. The organophosphate insecticide naled has been the insecticide of choice in this region. This study reports on analyses of 11 years (1984-94) of mosquito collection data from Cicero Swamp (Onondaga County) and Toad Harbor Swamp (Oswego County) in relation to applications of naled. Naled applications were successful in achieving short-term reductions in mosquito abundance. However, despite repetitive applications, populations of C. melanura have increased 15-fold at Cicero Swamp. Preventive applications had no noticeable impact on the enzootic amplification of EEE virus, and isolations of virus following preventive applications have resulted in additional spraying. The possibility that applications of naled contributed to increased populations of C. melanura discredits the rationale that preventive applications of naled reduce the risk of EEE.