Assessment of Sumishield<sup>®</sup> 50WG against Susceptible and Resistant Strains of <i>Anopheles gambiae</i> s.l.: Experimental Hut and Field Trials in Senegal

Malaria control efforts have led to a decline in incidence across Africa; however, the rise in insecticide resistance threatens these gains. This study evaluated the efficacy and residual activity of SumiShield® 50WG on cement and mud surfaces in Senegal. WHO cone bioassays were conducted using both susceptible and resistant strains of Anopheles gambiae s.l. The susceptible strain was tested monthly from August 2017 to July 2018, while the resistant strains were assessed five months after treatment. Knockdown was recorded at 30 and 60 minutes, and mortality at 24, 48, 72, and 96 hours. Trials were conducted in experimental huts and in two villages: Ndioukhane and Bandafassi. Knockdown rates at 30 and 60 minutes were low across all strains, surface types (cement and mud), and sites. In Bandafassi, 24-hour mortality exceeded the WHO threshold of 80%, except in month 4 on the mud surface, where it dropped to 65%. In Ndioukhane and at the experimental station, 24-hour mortality remained above 80% on both surface types from 7 days to 5 months post-treatment. At the experimental station, 48-hour mortality for all resistant strains also exceeded the 80% threshold on both surfaces. In Ndioukhane, 24-hour mortality consistently remained above the WHO threshold as well. These results demonstrate that SumiShield® 50WG is an effective insecticide for malaria vector control, showing high residual activity against both susceptible and resistant An. gambiae s.l. strains. Its efficacy on both cement and mud surfaces supports its potential as a promising alternative to insecticides compromised by resistance, offering a sustainable option for long-term malaria control.