The development of resistance mechanisms by mosquitoes modifies the effect of conventional insecticides and makes treatments less and less effective, according to our partner The Conversation.
A new strategy therefore combines two different chemical compounds with independent modes of action, namely a synergizing agent and an insecticide.
This analysis was conducted by Bruno Lapied, professor of neurophysiology at the University of Angers.
According to the World Health Organization (WHO), human diseases caused by parasites, viruses or bacteria transmitted by vectors (mosquitoes or ticks for example) also called vector-borne diseases represent, worldwide, approximately 17 % of infectious diseases.
Some of these diseases are transmitted by blood-sucking insects such as mosquitoes.
They can infect humans through viruses (arboviruses), such as dengue fever, chikungunya and Zika, or parasites (plasmodium) for malaria.
In this case, the latest WHO report shows an estimated 627,000 deaths from malaria in 2020. This corresponds to 69,000 more deaths than the previous year.
African regions are the most impacted with 96% of all malaria deaths in 2020, children under 5 are the main victims (80% of deaths).
In addition, the incidence of dengue fever, for example, continues to rise and the disease now affects people in more than 129 countries according to Dr Mwele Malecela, Director of the WHO Department of Control of Tropical Diseases neglected.
At the national level and in several French regions, in particular in the overseas territories (Martinique, Guadeloupe, Guyana, Mayotte, Reunion) and the overseas communities (New Caledonia, French Polynesia, Wallis and Futuna), control vector mosquito populations of the Aedes, Anopheles and Culex genera pose a real public health problem.
In addition, autochthonous cases of dengue in metropolitan France have been reported with 9 foci of dengue transmission representing 65 autochthonous cases identified as of October 16, 2022 in the Occitanie, Paca and Corsica regions.
Finally, the emergence and re-emergence of these vector-borne diseases transmitted by mosquitoes, due to climate change and the globalization of trade at the world level, reinforce the urgency of developing new essential strategies to manage and control these mosquito vector populations. 'Pathogens.
Varied but imperfect means of control
Today, the objectives of vector control (VCR) are to reduce but also to control vector mosquito populations.
Among the means of control used (biological, mechanical and/or genetic), chemical control by the use of biocides such as insecticides remains a widely used strategy.
However, the development of mechanisms of resistance to classic insecticides by mosquitoes and other physiological mechanisms of compensation (overexpression of specific target receptors) which limit the biological cost generated by the development of these resistances by these same mosquitoes modifies the insecticidal effect. and makes treatments less and less effective.
In this context, to limit the emergence of resistance in mosquitoes vectors of pathogens and reduce the concentration of insecticide used in order to avoid side effects on non-target organisms (such as beneficial insects or mammals), we have developed within the SiFCIR laboratory of the University of Angers in collaboration with the IRD of Montpellier (F. Chandre) and the SATT-Ouest valorisation of Rennes, an innovative strategy for the control of mosquitoes sensitive and resistant to insecticides .
The Synergizing Agent
This strategy is based on the use of a combination of two compounds from different chemical families having independent modes of action, namely a synergizing agent and an insecticide.
The synergizing agent, defined today within the framework of the collective expert report of ANSES (National Agency for Food, Environmental and Occupational Health Safety), is a synthetic or natural chemical compound which does not itself have insecticidal properties, but which, when combined and applied with an insecticide, considerably enhances its activity while reducing the concentrations used.
The major advantage of this combination, which acts on different targets, breaks the resistance development cycle observed for an insecticide.
This strategy makes it possible to intensify the effect of a given insecticide, which if it had been used alone would not have had such an important action.
Under these conditions and because the synergizing agent is used at a very low concentration, it does not cause harmful effects on living organisms and the environment.
It has the effect of activating intracellular signaling pathways involved in increasing the sensitivity of membrane targets to insecticides.
These signaling pathways, when solicited, are responsible for a change in the conformation of the target.
This effect increases the action of the insecticide while reducing the concentrations used and makes it possible to circumvent phenomena of resistance to insecticides.
OUR “MOSQUITOES” FILE
This new concept based on the use of a synergizing agent has been the subject of patents.
It has recently attracted the interest of industrialists in the fields of application related to the use of phytosanitary products.
This interest is part of the new approval procedures concerning the use of biocides at lower concentrations in a context of both environmental health and public health.
This analysis was written by Bruno Lapied, professor of neurophysiology at the University of Angers.
The original article was published on The Conversation website.
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