FRET/MCA of the DIIS6 region of the para -type sodium channel gene of An. gambiae s.s . and An. arabiensis plotted as the first negative derivative of the relative fluorescence unit (-d(RFU)/dT) versus temperature function. In all 3 panels, the thicker blue horizontal line denotes the threshold for background fluorescence, and the curve entirely below denotes the results for the non-template control (gray). A. Cloned sequence variants, from low to high Tm: The L1014S allele (red), the L1014F allele (blue) and the wild type L1014L allele (green). Melting peaks were identified at 49.5°C, 52°C and 57.5°C, respectively. B. An. gambiae s.s. specimens, from low to high Tm: homozygous for the L1014S allele, Tm of 49.5°C (red) ; specimens heterozygous for both kdr alleles (L1014S/L1014F allele), Tm of 51°C (dark red) ; specimens homozygous for L1014F allele, Tm of 52°C (blue) and specimens homozygous wild type, Tm of 57.5°C (green). C. An. gambiae s.s. specimens heterozygous for the L1014S/wild type (dark red) were characterised by two melting peaks of 49.5°C and 57.5°C. Heterozygous (L1014S/wild type) An. arabiensis specimens showed the same pattern.