Abstract
BackgroundMalaria control is heavily reliant on the use of insecticides that target and kill the adult female Anopheline vector. The intensive use of insecticides of the pyrethroid class has led to widespread resistance in mosquito populations. The intensity of pyrethroid resistance in some settings in Africa means mosquitoes can contact bednets treated with this insecticide class multiple times with minimal mortality effects. Furthermore, both ageing and diel cycle have been shown to have large impacts on the resistance phenotype. Together, these traits may affect other aspects of vector biology controlling the vectorial capacity or fitness of the mosquito.ResultsHere we show that sublethal exposure of a highly resistant Anopheles coluzzii population originally from Burkina Faso to the pyrethroid deltamethrin results in large and sustained changes to transcript expression. We identify five clear patterns in the data showing changes to transcripts relating to: DNA repair, respiration, translation, behaviour and oxioreductase processes. Further, we highlight differential regulation of transcripts from detoxification families previously linked with insecticide resistance, in addition to clear down-regulation of the oxidative phosphorylation pathway both indicative of changes in metabolism post-exposure. Finally, we show that both ageing and diel cycle have major effects on known insecticide resistance related transcripts.ConclusionSub-lethal pyrethroid exposure, ageing and the diel cycle results in large-scale changes in the transcriptome of the major malaria vector Anopheles coluzzii. Our data strongly supports further phenotypic studies on how transcriptional changes such as reduced expression of the oxidative phosphorylation pathway or pyrethroid induced changes to redox state might impact key mosquito traits, such as vectorial capacity and life history traits.
Highlights
Malaria control is heavily reliant on the use of insecticides that target and kill the adult female Anopheline vector
Over 2 billion insecticide treated bed nets (ITNs) have been distributed in Africa, the World Health Organisation (WHO) region accounting for the majority of the malaria burden worldwide; these nets are all treated with the pyrethroid class of insecticide
The experiments were designed to test three separate hypotheses: (i) Pyrethroid exposure induces changes to transcript expression over time; (ii) Ageing increases susceptibility to insecticides due to changes in expression of insecticide related transcripts and (iii) Diel cycle controls the expression of insecticide resistance transcripts
Summary
Malaria control is heavily reliant on the use of insecticides that target and kill the adult female Anopheline vector. The intensity of pyrethroid resistance in some settings in Africa means mosquitoes can contact bednets treated with this insecticide class multiple times with minimal mortality effects Both ageing and diel cycle have been shown to have large impacts on the resistance phenotype. Pyrethroid resistance reduces the personal protection provided by bed nets and importantly erodes the community protection afforded to non-net users by insecticide induced mortality, which has been critical for their success [7,8,9] To address this problem, net manufacturers have developed new classes of nets, several of which have already been pre-qualified by WHO and are in use in Africa. Pyrethroids will remain an essential critical chemistry for malaria prevention for the foreseeable future and understanding the effects of pyrethroid exposure and pyrethroid resistance on Anopheles mosquitoes is of fundamental importance
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
