First detection and entomological characterisation of invasive malaria vector Anopheles stephensi in sympatry with other vectors in Gayi Southern Niger Republic.

Anopheles stephensi, an invasive vector is aggressively expanding its geographic range across Africa, posing significant threat to malaria control. Surveillance of its spread is crucial for mitigating its impact on malaria transmission. Here, we report for the first time incursion of An. stephensi into Gayi, a rural area in southern Niger Republic. A combination of morphological identification, end point PCR and sequencing of fragments of COXI and ITS2 genes confirmed An. stephensi. This species was found resting indoor together with other mosquitoes, including An. coluzzii, An. gambiae s.s., and An. arabiensis. Entomological parameters, including resting densities, human blood index and biting rate, Plasmodium falciparum parasite rate, and entomological inoculation rate were described for the above Anopheles species. The finding of An. stephensi sympatric with the above major malaria vectors in Niger highlights the urgent need for intensified surveillance to develop evidence-based approaches to prevent further spread of this pervasive vector.