Additional Selection for Insecticide Resistance in Urban Malaria Vectors: DDT Resistance in Anopheles arabiensis from Bobo-Dioulasso, Burkina Faso

Abstract

In the city of Bobo-Dioulasso in Burkina Faso, Anopheles arabiensis has superseded Anopheles gambiae s.s. as the major malaria vector and the larvae are found in highly polluted habitats normally considered unsuitable for Anopheles mosquitoes. Here we show that An. gambiae s.l. adults emerging from a highly polluted site in the city centre (Dioulassoba) have a high prevalence of DDT resistance (percentage mortality after exposure to diagnostic dose = 65.8% in the dry season and 70.4% in the rainy season, respectively). An investigation into the mechanisms responsible found an unexpectedly high frequency of the 1014S kdr mutation (allele frequency = 0.4), which is found at very low frequencies in An. arabiensis in the surrounding rural areas, and an increase in transcript levels of several detoxification genes, notably from the glutathione transferase and cytochrome P450 gene families. A number of ABC transporter genes were also expressed at elevated levels in the DDT resistant An. arabiensis. Unplanned urbanisation provides numerous breeding grounds for mosquitoes. The finding that Anopheles mosquitoes adapted to these urban breeding sites have a high prevalence of insecticide resistance has important implications for our understanding of the selective forces responsible for the rapid spread of insecticide resistant populations of malaria vectors in Africa.

Re-Visiting Insecticide Resistance Status in Anopheles gambiae from Côte d'Ivoire: A Nation-Wide Informative Survey

“…gambiae s.s. population from areas with massive cotton production (Korhogo, Kaforo) displayed the highest resistance levels against almost all insecticides classes (organochlorides, pyrethroids and carbamates) as previously reported [34], [40]–[44]. Urban vegetable farming in Yopougon, Port-Bouët and Yamoussoukro areas was also associated with high levels of resistance, as previously detected [45]–[48]. The trend was not so clear within the rice-growing areas, generally associated with low application of insecticide [40], [44] but where moderate to high resistance level was found in An.gambiae [49].…”

Physiological correlates of ecological divergence along an urbanization gradient: differential tolerance to ammonia among molecular forms of the malaria mosquito Anopheles gambiae

“…gambiae sensu lato ( s.l. ) species complex—is extending its distribution southwards into urban environments [68,69], and has developed the ability to breed in larval habitats contaminated by waste waters [70,71]. In East Africa, members of the An.…”

“…Given these emerging trends, therefore, urban transmission is likely to hold an increasingly prominent place in malaria epidemiology, compared to the present situation [90-92]. Moreover, exposure to pollutants and xenobiotics in urban larval habitats may foster the evolution of insecticide resistance [46,47,71,78], thereby compromising our capacity to combat harmful vector-borne diseases like malaria, lymphatic filariasis, or Anopheles -transmitted arboviruses. It remains to be seen how the costs associated with increased tolerance may affect other fitness-related traits, e.g.…”

Insecticide resistance mechanisms associated with different environments in the malaria vector Anopheles gambiae: a case study in Tanzania

“…gambiae from an area of intense agriculture in lower Moshi (Kilimanjaro region) were found highly resistant to pyrethroids [17]. As in other African countries, elevated insecticide resistance levels of malaria vectors have also been identified in Tanzanian urban areas [16,27,32,35]. …”