• Insecticide Resistance

    • Research Sites

    The research sites

    The research was carried out in Mali, Nigeria and Benin. In each country, a number of sites where mosquitoes show resistance to the insecticides were identified. Where possible, localities where mosquitoes are still susceptible to insecticides were also considered.

    Mali

    No site of susceptibility was observed in Mali; therefore, sites where indoor residual spraying (IRS) was utilised (using a class of insecticides to which the Anopheles gambiae s.l. population is susceptible) and sites where IRS was not utilized were considered:

    • Koula and Karadiè in Koulikoro District (IRS and long-lasting insecticidal nets (LLINs) deployed)
    • N’Galamadibi and Kolondialan in Banamba District (no IRS, only LLINs)

    In Koulikoro and Banamba Districts, malaria transmission occurs mostly during the rainy season (June to October). An. gambiae s.l. is the predominant malaria vector in both study areas: > 98%.

    Nigeria

    The study sites in Nigeria were in Ikorodu District in south-western Nigeria, on the outskirts of Lagos:

    • Imota
    • Bayeku
    • Oreta
    • Igbokuta (control village)

    Preliminary data were collected from 12 sites on vector species, insecticide resistance and type of resistance mechanism(s). Based on the initial analysis conducted, the above four sites were selected for the study.

    The climate of this area is characteristic of the forest zone. The rainy season is from April to October and the dry season is from November to March. The area is usually flooded during the rainy season; larval aquatic habitats are abundant throughout the year.

    Benin

    No site of Pyrethroid susceptibility was recorded in Benin; therefore, two sites with consistent differences in resistance levels were considered:

    • Kpome, a site where Anopheles species are resistant to pyrethroids (13% mosquito mortality with Permethrin and 46% mortality with Deltamethrin); and

    • Ketonou, a site where Anopheles species are less resistant to pyrethroids (27% mosquito mortality with Permethrin and 76% mortality with Deltamethrin).

    Both localities are in the same agro-ecosystem.