Aedes albopictus responses to transfluthrin-impregnated polyester fabric in a semi-field system at different time periods

Abstract

Volatile pyrethroid spatial repellents produce airborne chemicals that cause insect repellency and provide personal protection to human users. This study investigated the effect of a passive emanator fabric on the human landing catch (HLC) of Aedes albopictus in a semi-field system (SFS) as well as post-exposure blood-feeding behavior, fecundity, and egg hatchability. A polyester fabric measuring 1029 cm² impregnated with 2.5 g/m² transfluthrin (TFT) (6.8 %, w/v) was attached to a black-screened vest to simulate insecticide-treated clothing. Two collectors wearing treated polyester fabric (TFT-P) or untreated fabric conducted HLC from opposite test arenas during morning (06:00–08:00 h) and evening (18:00–20:00 h) trials for 12 days. Recaptured surviving mosquitoes were provided a blood meal for 120 min. The protective efficacy—the percentage reduction of HLC in treatment compared to control—of TFT-P was 60.73 % during the morning trials compared to 31.97 % during the evening trials. Blood feeding was moderately reduced in exposed (37.5 % fed) and unexposed (67.7 % fed) mosquitoes during the morning trials. Similarly, egg hatchability was significantly low in exposed batches (31.2 % hatched) compared to the unexposed (54.5 % hatched) from the morning trials, but not the evening trials. The results highlighted the effect of trial time on TFT-P efficacy, mosquito feeding behavior, and egg hatchability. TFT-P could provide personal protection against Ae. albopictus by preventing bites and offering community protection by reducing feeding propensity. Further open-field tests and evaluations against other mosquito species are needed before public use.