Researchers at LSTM have found that there is genetic diversity in the expression of genes responsible for resistance to public health insecticides in major malaria vectors linked to geographical factors.

LSTM’s Director, Professor Janet Hemingway, is co–principal author on the paper along with LSTM’s Senior Wellcome Trust Research Fellow, Dr Charles Wondji. They worked alongside colleagues from Cambridge and Malawi studying the specific cytochrome genes in mosquitoes responsible for resistance to insecticide.

In the study, the results of which were published in the Proceeding of the National Academy of Sciences journal, the team looked at the major malaria vector Anopheles funestus, carrying out a genome wide genetic structure analysis with populations from Zambia, Malawi and Mozambique. Professor Hemingway said: “Vector control is the cornerstone of malaria prevention and the wide–scale distribution of treated bednets and indoor residual spraying in Africa has led to a massive decrease in mortality. However with many of the main malaria vectors now resistant to a number of different class of insecticides, including the only class used in the treatment of bednets, it has never been more important to understand the mechanisms of resistance in different mosquito populations.”

Analysis identified overexpression of cytochrome P450 genes as the main mechanism for driving resistance, and while there were three genes in particular that were the most up–regulated, the team detected a significant shift in the overexpression profile of those genes across a south/north transect. A genome wide genetic structure analysis of southern African populations of Anopheles funestus from Zambia, Malawi, and Mozambique revealed a restriction of gene flow between populations, in line with the geographical variation.

“This study shows that multiple CYP450s, genes are responsible for insecticide resistance, but that their impact varies significantly depending on geography” continued Professor Hemingway. “The finding of differences in the molecular basis of resistance within a given country means that national resistance management strategies that don’t take this into account may be flawed, and hopefully this knowledge should help improve resistance management and vector control strategies throughout southern Africa.”