18 Feb Oxford Brookes University DNA study offers crucial clues to mosquito disease control

A new study involving the DNA sequencing of mosquitoes in Laos, which spread malaria, dengue, chikungunya and the Zika virus, is uncovering the status of insecticide resistance in these disease carriers.

The research, conducted by 17 undergraduate students and Dr Andrew Jones from Oxford Brookes University’s Department of Biological and Medical Sciences, with Dr Sebastien Marcombe of Institut Pasteur du Laos, has found that ‘Anopheles’ mosquitoes, which spread malaria, and ‘Aedes’ mosquitoes, which spread chikungunya as well as the dengue and Zika viruses, lack a protein mutation in the GABA receptor that causes resistance to a group of insecticides called cyclodienes.

Dr Andrew Jones, senior lecturer in Molecular Biology and Genomics, explains: “The results of this study are a crucial part of analysing efforts to control the spread of disease-bearing mosquitoes. Our work shows this mutation is not found normally and, when it is present, is likely to exist because of the use of insecticides and some banned chemicals.

“Another class of insecticides known as pyrethroids are currently being used to control mosquitoes in Laos. We have found evidence that mosquitoes have strong resistance to these calling for the need of new public health strategies to manage dengue and other mosquito-borne diseases. One such strategy is to switch to different insecticide classes to prevent the selection of pyrethroid-resistant mosquito populations.

“Our research further recommends that insecticides acting on the GABA receptor are an appropriate alternative, as we have shown that resistance to these insecticides is very low in Laos.”

According to the World Health Organisation, malaria is endemic throughout most of Laos, largely in the southern part of the country. In 2012 there were 46,202 confirmed malaria cases and 44 deaths.

More recently in 2019 there were 33,728 reported cases of dengue, including 59 deaths up to October last year, the second highest number in Laos this century.

This study has been published in the Journal of Medical Entomology.