Mosquito collection method assessments for xenomonitoring in two cross-bordering villages with different ecosystems, Yanfolila, Mali, 2022-2023

Entomological surveillance is essential for the control of lymphatic filariasis (LF). This xenomonitoring study, conducted in 2022-2023, evaluated the effectiveness of three mosquito trapping methods to identify the most suitable tool for surveillance following the discontinuation of mass drug administration. The surveys took place in two Malian villages: Konfra (seasonal watercourse) and Siradjouba (permanent watercourse). Three techniques were compared: Pyrethrum spray catch (PSC) conducted at the end of each visit inside 30 randomly selected houses, and different collection points were chosen based on the characteristics of the study area to place the Ifakara Type C tent (Ifakara) and the gravid trap (GT). Collections were conducted simultaneously at both sites. All Anopheles gambiae and Culex spp. collected in 2022-2023 were morphologically identified and then analyzed in the laboratory for their infectious status. Data was processed using SPSS v25; Fishers exact test was used to compare proportions, with a significance threshold of p < 0.05. A total of 4,732 mosquitoes were captured (95.05% in 2022). In 2022, the Anopheles were predominant in Konfra (91.38%), while Culex predominated in Siradjouba (63.41%). In 2023, Anopheles was found only in Konfra (3 specimens), while Culex was predominant in Siradjouba (64.07%). In 2022, PSC collected 90.57% of Anopheles, Ifakara 9.43%, and GT 0%. For Culex, GT collected 53.67%, PSC 36.62%, and Ifakara 9.71%. In 2023, the few Anopheles (3) came from PSC; Culex were mainly collected by the Ifakara tent (43.29%). For FL xenomonitoring, the combination of PSC and the GT appear to be effective collection methods.