ULV SPRAYING WITH PERMETHRIN PRODUCT REDUCED ABUNDANCE, NOT ACTIVITY PATTERNS OF THE MOSQUITO, PSOROPHORA COLUMBIAE IN OPEN FIELD, NORTHEASTERN FLORIDA

Abstract

The floodwater mosquito Psorophora columbiae is an aggressive nuisance species and a potential vector of pathogens in Florida. Adulticiding using ultra-low volume (ULV) pyrethroid sprays is a primary operational control tool; however, little is known about the influence of ULV spraying on diel activity patterns of this species. This study examined whether a permethrin-based ULV spray affected the abundance and diel activity pattern of Ps. columbiae in open field, northeastern Florida. The study was conducted during the summer of 2009 at 526 hectares of sod farm in Elkton, Florida. Two mechanical rotating traps baited with dry ice were used to collect mosquitoes in hourly intervals over 16 hours to determine the activity patterns pre- and post-ULV sprays. Results showed that Ps. columbiae exhibited a pronounced activity peak between 20:00–21:00 hrs, extending from 05:00 hrs until 09:00 hrs the following morning. A permethrin product (Aqualure® 20-20) was then applied by a ULV spray truck from 19:00–20:00 hrs. The ULV spraying significantly reduced adult mosquito abundance, but diel activity patterns remained unchanged. These findings suggest that while permethrin ULV sprays suppress Ps. columbiae populations, however, they do not disrupt natural diel activity rhythms. This reinforced the importance of timing sprays to coincide with peak activity of target mosquitoes for operational effectiveness.