Degradation of cyfluthrin EC and WP residues on painted steel: Effects of commercial sealants on residual persistence

Abstract

Steel panels painted with white polyurethane or green latex were left unsealed or sealed with either Thompson's Water Seal or Olympic WaterGuard before treatment with cyfluthrin emulsifiable concentrate (EC) or cyfluthrin wettable powder (WP). Bioassays were conducted weekly for 10 weeks with Tribolium castaneum (Herbst) or Tribolium confusum (DuVal). Except for a few instances, neither species survived weekly bioassays of 24 h exposure on sealed or unsealed panels painted with white polyurethane and treated with cyfluthrin EC or WP. In contrast, from weeks 5–10 T. castaneum and T. confusum survival after 24 h exposure on sealed and unsealed panels painted with green latex was 40–100% and 10–83%, respectively, on panels treated with cyfluthrin EC. T. castaneum survival on unsealed panels and those sealed with Olympic WaterGuard and treated with cyfluthrin WP increased to 96 and 97% by week 6, while survival on panels sealed with Thompson's Water Seal was only 23%. T. confusum survival on unsealed panels and panels sealed with Olympic WaterGuard and treated with cyfluthrin WP was 87 and 90% by week 6, but survival on panels treated with Thompson's Water Seal was 0 until week 8.