Putative Pleiotropic Effects of the Knock-Down Resistance (L1014F) Allele on the Life-History Traits in Anopheles Gambiae.

Abstract BackgroundExisting mechanisms of insecticide resistance have been known to help the survival of mosquitoes following contact with chemical compounds, even though they could negatively affect the life-history traits of resistant malaria vectors. In West Africa, the knock-down resistance mechanism, kdrR (L1014F) is the most common. However, little knowledge is available on its effects on mosquito life traits. We investigated the fitness effects associated with this knock-down resistance allele in Anopheles gambiae sensu stricto (s.s.).MethodsTwo laboratory reference strains of An. gambiae s.s., Kisumu (susceptible) and KisKdr (kdr resistant) were used. Female mosquitoes were fed and allowed to lay eggs. Fecundity and fertility were assessed by examining the number of eggs per mosquito and larval hatching rates. Larval survivorship and pupation rates were also measured. Female mosquitoes of both strains were fed through membrane feeding assays, then the blood feeding success, blood volume and adult survivorship were monitored. ResultsAn. gambiae carrying kdrR allele (KisKdr) showed a lower ability to lay eggs. The mean number of larvae in the susceptible strain Kisumu was overall threefold higher than that seen in KisKdr strain with significant difference in the hatching rates (81.89% in Kisumu versus 72.89% in KisKdr, p= 0.003). KisKdr larvae had a significant higher larval survivorship than Kisumu. The blood feeding success was significantly higher (p= 2.2.10-16) in the resistant mosquitoes (84%) than that in the susceptible ones (34.75%). However, the mean blood volume was 1.36 µL/mg, 1.45 µL/mg and 1.68 µL/mg in Kisumu, homozygote and heterozygote KisKdr respectively. After blood feeding, the heterozygote KisKdr displayed highest survivorship when compared to that of Kisumu.ConclusionsOur findings provide novel insights on fitness effects of the kdrR (L1014F) allele in An. gambiae. The presence of this resistance allele tends to have an impact on mosquito life-history traits such as fecundity, fertility, larval survivorship and blood feeding behaviour. These data could help to guide the implementation of more reliable strategies for the control of malaria vectors.