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

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.