Impact of Naled aerial ULV application on butterfly larvae and control efficacy against adult mosquitoes

Aerial applications of mosquito adulticide are widely used by mosquito control programs to reduce adult mosquito population in targeted areas. Naled residue impact on Miami blue butterfly larvae (Cyclargus thomasi bethunebakeri) (Comstock & Huntington, 1943) (Lepidoptera: Lycaenidae) resting on one gallon nickerbean host plant (Caesalpinia bonduc) was assessed following aerial ULV applications in both spray and drift zones. We also evaluated the control efficacy against adult female salt-marsh mosquitoes (Aedes taeniorhynchus) (Wiedemann, 1821) (Diptera: Culicidae). The study was conducted in North Key Largo (Monroe County, Florida) and consisted of 15 test stations with 9 in spray target zone, 3 in non-targeted drift zone and 3 stations in control zone. Six field trials were conducted with 3 trials spray at 30.5 m (100 ft) and the other 3 trials at 45.7 m (150 ft) aircraft flight altitudes. The data showed that the naled ULV application at 54.8 ml per hectare (0.75 oz per acre) had excellent mosquito control efficacy in open area against adult female mosquitoes at the spray targeted zone. However, the butterfly larvae mortality in the spray zone was also significantly increased. The larvae mortality in drift zone was not significantly different from the control zone. Naled residue data from GC revealed that the butterfly mortality may due to the exposure of the excess amount of naled residue. Further studies are needed to reduce amount of naled residue but not compromise the satisfied mosquito control efficacy.