**5. Conclusion**

**4. Development of resistance to chemical insecticides**

124 Insecticides Resistance

Insecticide resistance is defined as the development of the ability of a insect population to tolerate doses of an insecticide, which would be lethal to the majority of individuals in a normal population of the same species and is also the result of pressure of positive selection exerted by the insecticide on the low frequency genes initially present in the vector insect [95]. Therefore, the development of resistance by mosquito disease vectors is of international concern due to the increase worldwide exchange of plant matter that mosquitoes can spread

Most mosquito vector control programs of diseases in humans are mainly based on the use of chemical insecticides by outdoor spraying, impregnated nets, or indoor residual spraying [96]. Thereon, the use of insecticides has helped to eradicate insect-borne diseases. In this regard, since 1950, different classes of insecticides have been successively used. Organophosphates and pyrethroid insecticides have been used to control mosquito populations in their larval and adult stages. However, more recently, the disease vector control programs are based largely on the use of synthetic pyrethroid insecticides, which are recommended by the WHO only for impregnated nets [97]. However, the massive use of pesticides has caused detrimental effects on the agroecosystem, such as the acquisition of resistance, pest resurgence, and environmental pollution. Resistance has developed in more than 84 species of mosquitoes for each of the groups of toxicological insecticides [98]. Furthermore, it was found that insecticide residues accumulated in plants often end up in water bodies where mosquito larvae feeding on such plant debris or grow in water bodies enriched with plant compounds and interactions between these xenobiotics generate tolerance to insecticides or promote detoxification pathways of these insecticides against mosquitoes [99]. In addition to abiotic factors, biotic interactions that occur among mosquitoes, the pathogens that they transmit and their microbiome (microbes living in the mosquito) may also occur [96]. These vary from symbionts to entomopathogen opportunistic organisms that are able to affect various physiological host processes, such as detoxification systems [100] or the opposite effect leading to the appearance of insecticide resistance [101]. Furthermore, allelochemicals inducing enzyme production in insects can increase their tolerance to pesticides [102]. On the other hand, other studies have shown that

to other parts of the world, spreading resistance genes of the plagues that they have.

the degree of development of a plant can affect insecticide resistance in insects [103].

penetration through the cuticle or cross resistance [104].

**4.1. Resistance mechanisms**

There are two main mechanisms by which mosquito vectors can develop resistance to insecticides: alterations in the target site of action and metabolic resistance, also called increased rate of detoxification of insecticides [19]. Other less common mechanisms that develop resistance in insects are the resistance per behavior and the resistance per decreased

Each insecticide triggers the selection of one or more mechanisms of resistance; in addition, an unknown number of behavioral changes in adults. For instance, changes in the target site of action are produced when no silent mutations occur in structural genes that produce an alteration of amino acids responsible for anchoring the insecticide at a specific site. For Mosquito-borne diseases are influenced by biological, ecological, social, and economic factors. Unfortunately, in most cases, deaths occur in rural areas where medical care is inadequate because resources are limited. Some of the mosquito-borne disease symptoms are mild and easy to treat; however, for other disease, antiviral drugs and antibiotics are not effective for controlling the virus, and there is still no vaccine available for prevention. One of the strategies used as a preventive measure to control the spread of diseases is the elimination of mosquitoes and their breeding sites. The main strategy for the elimination of mosquitoes is the use of chemical insecticides. However, their control is complicated because the frequent use of chemical insecticides generates resistance and the insecticides decrease their effectiveness. The use of plants, fungi, and bacteria with potential activity have some beneficial effects for the environment, but its duration is limited and some mosquitoes develop high resistance. A promising alternative is the use of chemicals and natural insecticides intended to modify the normal functioning of the mosquitoes that transmit diseases and which do not affect the environment.
