Residual Effectiveness of Three Pyrethroids on Vegetation Against Adult Aedes albopictus and Culex quinquefasciatus in Screened Field Cages

Abstract

The residual effectiveness of pyrethroid-treated vegetation as a barrier against female host-seeking Aedes albopictus and Culex quinquefasciatus was evaluated in large screened-cage field tests for 12 wk. Individual potted southern wax myrtle (Myrica cerifera L.) plants were treated with either beta-cyfluthrin (Tempo SC Ultra©), lambda-cyhalothrin (Demand CS©), or tau-fluvalinate (Mavrik Perimeter©) at maximum label rates. Suction mosquito traps (MMX) baited with carbon dioxide placed near plants treated with tau-fluvalinate provided significant overall reduction (≈62–80%) of mosquitoes through 2 wk compared with untreated plants. Overall percent knockdown/mortality from excised-leaf bioassays was similar to suction-trap reduction data. However, knockdown/mortality in leaf bioassays was greater for Ae. albopictus than for Cx. quinquefasciatus, whereas no such effect was observed in trap collections. Mosquito abundance in MMX collections near plants treated with beta-cyfluthrin provided similar levels of reduction as tau-fluvalinate–treated plants through 1 wk and 3–4 wk after treatment. Leaf toxicity generally provided ≈>90% knockdown/mortality on beta-cyfluthrin–treated leaves throughout the study. Generally, no consistent difference in trap reduction or weekly knockdown/mortality in leaf bioassays was observed between either mosquito species. Plants treated with lambda-cyhalothrin provided significantly greater overall reduction of mosquitoes (75–83%) from MMX collections for the first 5 wk compared with untreated plants. Knockdown/mortality levels and duration of leaf toxicity from lambda-cyhalothrin–treated leaves was similar to that of beta-cyfluthrin, with no consistent differences between mosquito species.