Evaluation of the Efficacy of Barrier Sprays Conducted by a Private Backyard Mosquito Control Company in a Suburban Neighborhood in Eastern North Carolina

Mosquitoes are nuisance pests and a public health concern, with the potential to transmit viruses to humans through blood feeding. Mosquito control programs (MCPs) provide services to control and reduce mosquito populations by performing mosquito surveillance and using ultra-low volume insecticide sprays to treat neighborhoods. In July 2011, North Carolina (NC) disbanded the Public Health Pest Management (PHPM) section of the Department of Environmental and Natural Resources (DENR). As a result state-wide resources were no longer available to MCPs. Without state-wide coordinated mosquito management, local residents without county or municipal control programs must handle mosquito control on their own. Private mosquito control companies offer abatement services to residents, using barrier sprays to treat their properties, but may have limited time to perform mosquito surveillance. The goal of the present study was to determine the efficacy of the barrier spray to control mosquitoes. Ten residential properties in Greenville, NC were sampled weekly for host-seeking mosquitoes. Five properties received barrier spray treatment and five did not. Leaf samples were collected weekly from treatment properties and pesticide residue was quantified by gas chromatography (GC). Weekly total host-seeking mosquito collections from treatment properties were consistently lower than control properties with mean reduction 53.6% (SE=0.039, range 24.0-75.0%). The difference between mean values for total mosquitoes over all weeks was significant (p<0.000), but varied among genera. Bifenthrin residue was detected on leaves from treatment properties, but quantities were not correlated (p<0.05) with total mosquito collections. Immature mosquitoes (primarily Aedes albopictus) were collected monthly and reared to adulthood for use in pesticide resistance assays. Although field-collected mosquitoes were more resistant than colonized mosquitoes during the CDC bottle bioassay test, results during the initial 30 minute diagnostic time did not suggest resistance. Findings from this study may have implications for mosquito control and could potentially be used to guide future mosquito management strategies