Search

Additional file 1 : Figure S1. % Mortality of VK7 (lowly resistant, LR) and VK7 (highly resistant, HR) after 24 hours of 1 hour deltamethrin exposure. Two doses were used , the diagnostic (0.05% deltamethrin), where all VK7 LR were dead and all VK7 HR tested were alive and one lower dose (0.0016%), where almost half VK7 LR survived (LC50) and no mortality was recorded for VK7 HR. Figure S2. Graphical depiction of leg dissections, just on their adhesion to the thorax, in order to isolate whole legs including all their segments (coxa, trochanter, femur, tibia, tarsus). Figure S3. Principal components analysis of the gene expression levels for the An. coluzzii leg and whole body samples. Figure S4. Principal components analysis of the gene expression levels for the four An. coluzzii samples. Replicates N���Gousso_3, VK7-HR_4 and VK7-IN_2 that do not follow the expected pattern were excluded from all downstream analyses. Figure S5. Over-represented GO terms (A) in the 359 up-regulated, and (B) in the 477 down-regulated genes in the An. coluzzii leg compared to whole body. Figure S6. Over-represented GO terms (A) in the 73 commonly up-regulated, and (B) in the 159 commonly down-regulated genes in the two comparisons related to constitutive resistance (VK7-HR vs VK7-LR and VK7-HR vs N���Gousso). Figure S7. Enriched functions in the 348 up-regulated genes, after induction with deltamethrin (VK7-IN versus VK7-HR). Figure S8. Phylogenetic comparison between the An. coluzzii and the C. pipiens pallens opsin genes. This analysis shows that three of the up-regulated An. coluzzii opsin genes after deltamethrin exposure (GPROP1, GPROP3, GPROP4) form a sister clade to that containing NYD-OP7 in C. pipiens pallens. The up-regulated An. gambiae opsin genes after deltamethrin exposure are marked with a red star, while the scale bar refers to substitutions per site. The tree was midpoint-rooted to resolve an existing trifurcation.

International audience

Malaria control is dependent on the use of longlasting insecticidal nets (LLINs) containing pyrethroids. A new generation of LLINs containing both pyrethroids and the synergist piperonyl butoxide (PBO) has been developed in response to increasing pyrethroid resistance in African malaria vectors, but questions remain about the performance of these nets in areas where levels of pyrethroid resistance are very high. This study was conducted in two settings in southwest Burkina Faso, Vallée du Kou 5 and Tengrela, where Anopheles gambiae s.l. (Diptera: Culicidae) mortality rates in World Health Organization (WHO) discriminating dose assays were

Resistance to first-line treatments for Plasmodium falciparum malaria and the insecticides used for Anopheles vector control are threatening malaria elimination efforts. Suboptimal responses to drugs and insecticides are both spreading geographically and emerging independently and are being seen at increasing intensities. Whilst resistance is unavoidable, its effects can be mitigated through resistance management practices, such as exposing the parasite or vector to more than one selective agent. Resistance contributed to the failure of the 20th century Global Malaria Eradication Programme, and yet the global response to this issue continues to be slow and poorly coordinated—too often, too little, too late. The Malaria Eradication Research Agenda (malERA) Refresh process convened a panel on resistance of both insecticides and antimalarial drugs. This paper outlines developments in the field over the past 5 years, highlights gaps in knowledge, and proposes a research agenda focused on managing resistance. A deeper understanding of the complex biological processes involved and how resistance is selected is needed, together with evidence of its public health impact. Resistance management will require improved use of entomological and parasitological data in decision making, and optimisation of the useful life of new and existing products through careful implementation, combination, and evaluation. A proactive, collaborative approach is needed from basic science and the development of new tools to programme and policy interventions that will ensure that the armamentarium of drugs and insecticides is sufficient to deal with the challenges of malaria control and its elimination., Janet Hemingway and colleagues examine progress in research on insecticide and drug resistance in malaria elimination and eradication and propose a research agenda.

Background: Urban malaria is becoming a major health priority across Africa. A study was undertaken to assess the importance of urban pollution and agriculture practice on the distribution and susceptibility to insecticide of malaria vectors in the two main cities in Cameroon. Methods: Anopheline larval breeding sites were surveyed and water samples analysed monthly from October 2009 to December 2010. Parameters analysed included turbidity, pH, temperature, conductivity, sulfates, phosphates, nitrates, nitrites, ammonia, aluminium, alkalinity, iron, potassium, manganese, magnesium, magnesium hardness and total hardness. Characteristics of water bodies in urban areas were compared to rural areas and between urban sites. The level of susceptibility of Anopheles gambiae to 4% DDT, 0.75% permethrin, 0.05% deltamethrin, 0.1% bendiocarb and 5% malathion were compared between mosquitoes collected from polluted, non polluted and cultivated areas. Results: A total of 1,546 breeding sites, 690 in Yaounde and 856 in Douala, were sampled in the course of the study. Almost all measured parameters had a concentration of 2- to 100-fold higher in urban compare to rural breeding sites. No resistance to malathion was detected, but bendiocarb resistance was present in Yaounde. Very low mortality rates were observed following DDT or permethrin exposure, associated with high kdr frequencies. Mosquitoes collected in cultivated areas, exhibited the highest resistant levels. There was little difference in insecticide resistance or kdr allele frequency in mosquitoes collected from polluted versus non-polluted sites. Conclusion: The data confirm high selection pressure on mosquitoes originating from urban areas and suggest urban agriculture rather than pollution as the major factor driving resistance to insecticide.

Parasitoid Wasp Genomes Parasitoid wasps, which prey on and reproduce in host insect species, play important roles in plant herbivore interactions, and may provide valuable tools in the biological control of pest species. The Nasonia Genome Working Group (p. 343 ; see the news story by Pennisi ) presents the genome of three very closely related species: Nasonia vitripennis, N. giraulti , and N. longicornis . The findings document rapid evolution between a host and endosymbiont that can cause nuclear-cytoplasmic incompatibilities that may affect speciation.

Pyrethroid insecticides prolong the opening of voltage-dependent sodium channels in insect nerves to produce instant paralysis and “knock-down.” Many insects have evolved knock-down resistance through nonsynonymous mutations that reduce pyrethroid binding in the channels. In 2006 we discovered one such mutation in the arbovirus mosquito vector Aedes aegypti, called Ile1,016, that confers very high knockdown resistance to the pyrethroid insecticide permethrin in mosquitoes homozygous for this mutation. We examined collections of Ae. aegypti from México during 1996–2009 and found that the overall Ile1,016 frequency increased from

International audience

Background Metabolic resistance to insecticides is the biggest threat to the continued effectiveness of malaria vector control. However, its underlying molecular basis, crucial for successful resistance management, remains poorly characterized. Results Here, we demonstrate that the single amino acid change L119F in an upregulated glutathione S-transferase gene, GSTe2, confers high levels of metabolic resistance to DDT in the malaria vector Anopheles funestus. Genome-wide transcription analysis revealed that GSTe2 was the most over-expressed detoxification gene in DDT and permethrin-resistant mosquitoes from Benin. Transgenic expression of GSTe2 in Drosophila melanogaster demonstrated that over-transcription of this gene alone confers DDT resistance and cross-resistance to pyrethroids. Analysis of GSTe2 polymorphism established that the point mutation is tightly associated with metabolic resistance to DDT and its geographical distribution strongly correlates with DDT resistance patterns across Africa. Functional characterization of recombinant GSTe2 further supports the role of the L119F mutation, with the resistant allele being more efficient at metabolizing DDT than the susceptible one. Importantly, we also show that GSTe2 directly metabolizes the pyrethroid permethrin. Structural analysis reveals that the mutation confers resistance by enlarging the GSTe2 DDT-binding cavity, leading to increased DDT access and metabolism. Furthermore, we show that GSTe2 is under strong directional selection in resistant populations, and a restriction of gene flow is observed between African regions, enabling the prediction of the future spread of this resistance. Conclusions This first DNA-based metabolic resistance marker in mosquitoes provides an essential tool to track the evolution of resistance and to design suitable resistance management strategies.