The widespread use of household insecticides represents a potential but often overlooked source of selection pressure contributing to insecticide resistance in malaria vectors. In Côte d'Ivoire, resistance to pyrethroids is widespread; however, the role of domestic insecticide practices in shaping metabolic resistance mechanisms remains poorly documented. A cross-sectional household survey was conducted in 3 urban localities of Côte d'Ivoire (Abengourou, Daloa, and Gagnoa) to characterize insecticide use patterns, frequencies, and application practices. In parallel, larvae of Anopheles gambiae s.l. were collected from the same localities, reared to adulthood, and analyzed for the expression of 8 detoxification genes (CYP6P3, CYP6M2, CYP9K1, CYP6P4, CYP6Z1, GSTE2, CYP6P1, and CYP4G16) using quantitative real-time PCR. Gene expression levels were compared with those of the insecticide-susceptible reference strain Anopheles gambiae Kisumu using REST software. Overall, 63.0% of households reported regular use of insecticides, with marked heterogeneity between sites Pyrethroid-based formulations, predominantly permethrin-transfluthrin combinations, were the most commonly used products. Household insecticide consumption was highest in Abengourou, exceeding 2 aerosol cans (300 ml) per week. Molecular analyses revealed significant overexpression of CYP6P1 in An. gambiae s.l. from Abengourou and CYP6Z1 in populations from Daloa and Gagnoa compared with the Kisumu reference strain. The intensive and recurrent use of household insecticides is associated with the presence of metabolic resistance markers; however, causality cannot be established. These findings highlight the need to integrate domestic insecticide practices into national insecticides resistance management strategies.
Ekra et al. (Fri,) studied this question.