Performance of different spatial repellents (spatial emanators) against vector mosquito species in Mali, West Africa: a field trial using a non-human test method

Introduction: -dominated) field sites in Mali, West Africa. Methods: ‑baited CDC‑UV traps, positioned 14 ft from the device, to quantify spatial protection. Results: ) at the same site. Dunnett's multiple comparisons confirmed that these were the only treatments to produce significant reductions across multiple genera at both sites. Mosquito coils offered moderate but inconsistent protection, while the citronella candle and ultrasonic device showed minimal or no measurable effect, aligning with previous findings that citronella‑based products provide little field efficacy. This characterization of "inconsistent" reflects the night‑to‑night fluctuations in percent reduction, which are evident in the raw data (not shown) and already conveyed in the reported means and confidence intervals. Discussion: Together, these results demonstrate that heat‑activated volatile pyrethroid devices can deliver strong, broad‑spectrum spatial protection across ecologically varied environments. The study emphasizes the need for standardized, wind‑controlled field testing and highlights significant performance gaps among widely marketed consumer repellents. Given that spatial repellents are now formally recognized as a recommended intervention class in the 2025 WHO Guidelines, these performance gaps carry important public health implications, as inconsistent or underperforming products could undermine the protective value expected from this intervention category.