**5. Effect of the physiological status of mosquitoes on the efficacy of insecticides**

Different studies have compared the behavioral response of mosquitoes under different physiological conditions, including age. Experiments were carried out on *Ae. aegyti* females with four different physiological conditions: parous, without copulating, copulating (nulliparous), and fed to repletion. The results show that females without copulating and nulliparous females had higher responses of irritation and repellency than parid or newly fed females [3]. Polsomboon et al. [72] evaluated the relationship of the same physiological conditions in two pyrethroids; all the assessed females, regardless of their physiological state, were susceptible to deltamethrin and resistant to DDT; and two of the test groups from the same populations (without mating and nulliparous) showed higher mortality to DDT compared with parid females and recently fed females. Because blood can serve as an additional glycogen and protein storage, mosquitoes that were not mating or feeding showed reduced vigor in both insecticide tests.

Oliver & Brooke [73] were the first to demonstrate the expression of resistance to insecticides because of multiple blood feedings; they also point out the variability of the expression levels of detoxification enzymes as a function of age that presented a decrease in these due to aging. This could be because blood feeding can modify the expression of genes that affect the action of detoxifying enzymes. This expression is more evident during the first, second, and third days following a single blood feeding showing a dependence on sex [74].

This association seems to influence mosquito susceptibility or resistance to insecticides in terms of mosquito parasitism. According to Agnew et al. [75], parasitism can act as a source modifying the costs of resistance to organophosphate insecticides and as qualitatively different interactions (increasing or decreasing relative fitness in resistant individuals) that occur depending on the type of resistance involved.

In several insect groups and disease vectors across the world, "physiological" resistance, metabolic, and target site modifications to insecticides have been well documented [76], including highly physiologically insecticide-resistant mosquitoes. It also implies the application of chemical products at higher concentrations, which is neither practically feasible nor cost-effective [12].

#### **6. Conclusions**

Although the behavioral responses of mosquito vectors to insecticides differ based on the type of product and concentration, it is also true that the product's properties (irritant-repellent) can help to reduce human-vector interaction. The behavioral response of avoiding the treated surface seeks to integrate products with such properties to reduce the transmission of pathogens because they reduce the opportunity for blood feeding. Understanding mosquito behavior, including oviposition site selection, dispersal behavior, and competitive mating, can allow the development of innovative

*Mosquito Excito-Repellency: Effects on Behavior and the Development of Insecticide Resistance DOI: http://dx.doi.org/10.5772/intechopen.105755*

mosquito surveillance and control strategies to control these important and deadly insects better. On the other hand, molecular and structural studies and the signaling pathways of these receptors must be studied better to understand their function and role in resistance development.
