Cuticular hydrocarbons are associated with mating success and insecticide resistance in malaria vectors

Abstract

Anopheles coluzzii females, important malaria vectors in Africa, mate only once in their lifetime. Mating occurs in aerial swarms with a high male-to-female ratio, where traits underlying male mating success are largely unknown. Here, we investigated whether cuticular hydrocarbons (CHCs) influence mating success in natural mating swarms in Burkina Faso. As insecticides are widely used in this area for malaria control, we also determined whether CHCs affect insecticide resistance levels. We find that mated males have higher CHC abundance than unmated controls, suggesting CHCs could be determinants of mating success. Additionally, mated males have higher insecticide resistance under pyrethroid challenge, and we show a link between resistance intensity and CHC abundance. Taken together, our results suggest that CHC abundance may be subject to sexual selection in addition to selection by insecticide pressure. This has implications for insecticide resistance management, as these traits may be sustained in the population due to their benefits in mating even in the absence of insecticides.

Sympatric Populations of the Anopheles gambiae Complex in Southwest Burkina Faso Evolve Multiple Diverse Resistance Mechanisms in Response to Intense Selection Pressure with Pyrethroids

“…Elevated levels of cuticular hydrocarbons have been associated with pyrethroid resistance in An. coluzzii mosquitoes from Valle du Kou [ 10 , 54 ] in Burkina Faso and evidence of an association between epicuticle thickness and insecticide resistance has been reported in several additional Anopheles populations [ 11 , 55 ]. As this resistance mechanism may confer cross resistance to a wide range of contact insecticides, it is important that insecticide screening pipelines incorporate strains with thickened cuticles.…”

“…As this resistance mechanism may confer cross resistance to a wide range of contact insecticides, it is important that insecticide screening pipelines incorporate strains with thickened cuticles. However, our own observations indicate that this mechanism may be less stable in laboratory colonies than other resistance mechanisms, perhaps indicative of a high fitness cost which is balanced by other phenotypic advantages, such as ability to withstand desiccation [ 56 ], or mating advantage [ 10 ].…”

“…However, recent studies on Anopheles gambiae s.l. mosquito populations from West Africa have identified additional, potent pyrethroid resistance mechanisms such as reduced penetration caused by cuticular thickening [ 10 , 11 ], insecticide sequestration by pyrethroid binding proteins in the mosquito appendages and novel resistance associated haplotypes of the pyrethroid target site, the voltage gated sodium channel (VGSC) [ 12 , 13 , 14 ]. Several of these resistance mechanisms could potentially cause cross resistance to existing or new classes of insecticides; thus, we sought to establish new colonies of pyrethroid resistant An.…”

Antimalarials in mosquitoes overcomeAnophelesandPlasmodiumresistance to malaria control strategies

“…The An. coluzzii mosquitoes endemic to this part of Burkina Faso – hereafter named AcVK5 – are highly resistant to pyrethroids (9, 11, 26). AcVK5 mosquitoes were exposed to ATQ for 6 minutes (min) at two concentrations (100 µmol- or 1 mmol/m 2 ) or a mock-treated blank control surface prior to feeding on infectious blood samples.…”

Screening for odorant receptor genes expressed in Aedes aegypti involved in host-seeking, blood-feeding and oviposition behaviors

“…Cuticular hydrocarbons of the mosquito egg have been listed as oviposition pheromones for Ae. aegypti [ 32 ]. We found that OR38, OR93, OR110, OR112, OR115-V2 and OR115-V3 genes were highly expressed before oviposition and that their expression decreases after oviposition, suggesting that they may play a role in mosquito oviposition in combination with oviposition stimulants.…”