Preliminary evaluation of mass-trapping of Aedes aegypti by the Gravid Aedes Trap (GAT) in Brazil

• This study reports the first implementation of the mass-trapping technique using GAT traps to assess mosquito population suppression in an urban setting in Brazil. • Three treatments were used: Reference, with no traps during the intervention; one trap per property; and two traps per property during the intervention. • Spatial analyses indicate that the use of mass-trapping traps reduced mosquito density in central blocks, whereas in the control treatment hotspots were observed both in central and peripheral blocks. • Monitoring traps detected ZIKV in field-collected mosquitões. • In the 2-GAT treatment, entomological indicators reached zero at the end of the intervention and remained so during the 3-week post-intervention phase, indicating a strong potential of this method for Aedes aegypti population suppression. This study presents a preliminary evaluation of the mass trapping of Aedes aegypti using traps for gravid Aedes mosquitoes (GATs), which have proven to be a promising alternative for urban vector control. This study evaluated, for the first time in Brazil, the suppressive effect of GATs under field conditions concomitant with the actions of the vector control program in the municipality of Piumhi, Minas Gerais. Three treatments were compared: a reference area without intervention, and two intervention areas with one or two traps per property. Over 13 weeks (pre-intervention, intervention, and post-intervention phases), 747 mosquitoes were captured, of which Ae. aegypti represented over 90%, with a strong predominance of females. Entomological indices demonstrated significant reductions in the mean number of adult females (MAF) in intervention blocks, particularly in the two-traps-per-property treatment, where no females were detected during the final intervention and post-intervention weeks. The GAT Positivity Index declined substantially in both intervention treatments, reaching 0% in the two-traps-per-property area. Kernel density analyses confirmed suppression, showing the absence of persistent hotspots in intervention zones, in contrast with the reference area. RT-PCR screening revealed Ae. aegypti females infected with Zika virus in intervention treatments, but none in the reference area, marking the first evidence of viral circulation in Piumhi through entomological surveillance. Meteorological variables, especially temperature and humidity, were positively correlated with mosquito abundance in intervention blocks. These findings indicate that GAT-based mass-trapping can suppress Ae. aegypti populations in urban environments, even with moderate community coverage, and may complement existing vector control strategies to reduce arbovirus transmission risk.