The pyrethroid knock‐down resistance gene in the Anopheles gambiae complex in Mali and further indication of incipient speciation within An. gambiae s.s.

Abstract

In Mali the Anopheles gambiae complex consists of An. arabiensis and Mopti, Savanna and Bamako chromosomal forms of An. gambiae s.s. Previous chromosomal data suggests a complete reproductive isolation among these forms. Sequence analysis of rDNA regions led to the characterization of two molecular forms of An. gambiae, named M-form and S-form, which in Mali correspond to Mopti and to Savanna/Bamako, respectively, while it has failed so far to show any molecular difference between Savanna and Bamako. The population structure of An. gambiae s.l. was analysed in three villages in the Bamako and Sikasso areas of Mali and the frequency of pyrethroid resistance of the knock-down resistance (kdr) type was calculated. The results show that the kdr allele is associated only with the Savanna form populations and absent in sympatric and synchronous populations of Bamako, Mopti and An. arabiensis. This is the first molecular indication of barriers to gene flow between the Bamako and Savanna chromosomal forms. Moreover, analyses of specimens collected in the Bamako area in 1987 show that the kdr allele was already present in the Savanna population at that time, and that the frequency of this allele has gradually increased since then.

The spatial distribution of Anopheles gambiae sensu stricto and An. arabiensis (Diptera: Culicidae) in Mali

“…In Mali resistant alleles of kdr have been reported only in the chromosomal form Savannah of An. gambiae s.s. (Fanello et al, 2003). Based on these results, insecticide resistance monitoring and management must be primarily focused on the humid savannah, along the rivers and in the inner delta of Niger where a higher frequency of An.…”

Adaptive introgression in an African malaria mosquito coincident with the increased usage of insecticide-treated bed nets

“…This study provides a rare example of adaptive introgression in an animal species and elucidates the dynamics of how insecticide resistance evolved in A. coluzzii. (14), but was found to be absent in sympatric A. coluzzii populations (16)(17)(18). The first report of L1014F in A. coluzzii came in 2000 from samples collected in southern Benin.…”

Dramatic Decrease in Malaria Transmission after Large-Scale Indoor Residual Spraying with Bendiocarb in Benin, an Area of High Resistance of Anopheles gambiae to Pyrethroids

“…[6][7][8][9] In the past decade, the emergence of resistance in populations of An. gambiae to common classes of insecticides used in public health has been reported in many countries in Africa, including Côte d'Ivoire, 6 Kenya, 10 Benin, 11,12 Niger, 13 Burkina Faso, 14 Mali, 15 Nigeria, 16 South Africa 17 and Cameroon. 18 In addition, N'Guessan and others 19 have demonstrated a decrease in the efficacy of treated nets and IRS using pyrethroids against An.…”