**2. Mosquito feeding behavior**

Feeding is a fundamental need of every animal to achieve their optimal growth, survival, and reproductive requirements. But the strategy of food intake and the feeding preference largely vary depending on the internal metabolic needs, i.e., whether they are starved or satiated; on the internal physiological state, i.e., whether they are virgin or mated and gravid or unfed; and also on the external sensory stimuli. In the case of mosquitoes, plant sugars such as nectar and honeydew are the primary energy source for survival, flight, and foraging activities of both males and females. Only adult female mosquitoes take blood meal as an optional dietary supplement, and this specialization is predicted to evolve for better fitness [7–9]. Genetic architecture and the allelic polymorphism of different mosquito species influence their traits towards selection and preference for feeding hosts. Apart from that other internal factors such as circadian rhythm and physiological status including nutritional and mating status, as well as environmental factors such as temperature and humidity, affect mosquito feeding behavior cumulatively [10, 11] (**Figure 1**).

Each feeding event of mosquitoes is initiated by random navigation from a long distance, which becomes specific when triggered by a certain group of chemicals such as CO2, lactic acid, 1-Octen-3-Ol, acetone, ammonia, etc. The detection of other additional cues such as visual and thermal factors facilitates the downstream events of host localization, landing over the host and searching for a suitable site for probing by the proboscis to initiate blood-feeding. But, successful navigation does not always corroborate with a successful feeding event, because it involves another level of regulation of the central nervous system by discriminating the

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**Figure 2.**

**Figure 1.**

*either starved or satiate.*

*Neuro-Olfactory Regulation and Salivary Actions: A Coordinated Event for Successful…*

*Factors affecting mosquitoes' feeding behavior. The genetic structure, circadian cycle, mating status, internal nutritional status, and external environmental factors such as temperature and humidity cumulatively work to shape the mosquitoes' feeding preference toward either sugar meal or blood meal. The internal nutritional status is dependent on larval nutrition, the amount of nutrient storage, and the feeding condition of the mosquito, i.e.,* 

odor molecules and making a decision for either to feed or not. Post landing and piercing on a particular site of the vertebrate host, successful uptake of blood meal largely depends on the proper functioning of the salivary gland which acts as the final action machinery by facilitating the feeding process through salivation. Thus, here we provide a detailed integrative description of (1) how mosquitoes detect

*picture was taken from the research article by Ghosh et al. [12].*

*The path of signal processing for achieving successful mosquito navigation and feeding. The tripartite interorgan communication among three tissues, viz., olfactory tissue, central nervous system (brain), and the salivary gland, is crucial for the completion of feeding events. The olfactory tissue (highlighted by purple circle) senses and binds to odor molecules emanating from either plant or vertebrate host and sends the respective signal towards the brain system (highlighted as yellow circle). After processing the initial signal of odor in the central nervous system, the decision-making process occurs, and then the brain sends the signal towards the salivary gland (highlighted as red circle), and the process of salivation started to facilitate feeding. Photo credit goes to Zwiebel Lab, Vanderbilt University, for the olfactory system of* Anopheles *mosquito. The salivary gland* 

*DOI: http://dx.doi.org/10.5772/intechopen.90768*

*Neuro-Olfactory Regulation and Salivary Actions: A Coordinated Event for Successful… DOI: http://dx.doi.org/10.5772/intechopen.90768*

#### **Figure 1.**

*Sino-Nasal and Olfactory System Disorders*

**2. Mosquito feeding behavior**

feeding behavior cumulatively [10, 11] (**Figure 1**).

*vivax* which infects millions of people each year, posing a major threat to society [2]. Arboviruses, viz. dengue, Zika, chikungunya, and yellow fever viruses, are also significant mosquito-borne pathogens that are mainly vectored by *Aedes* mosquitoes. The mosquito-borne diseases not only are restricted to underdeveloped countries but also escalate in the developed world. Urbanization, continuous climate change, global warming, and other environmental factors are facilitating mosquitoes' adaptation and survival during adverse situations [3, 4]. Taken together, it is not hard to predict the situation of mosquito and other insect-borne diseases becoming exacerbate in the coming century [5, 6]. Even the diverse ecological and epidemiological settings within Southeast Asia favor the association of diverse Anopheline fauna which makes malaria prevalence and malaria eradication more challenging. In order to save humans from the mosquito's infectious bites, advanced chemical insecticide(s) still play a central role; however, fast emergence of insecticide resistance and increased toxicants to the environment demands the development of new molecular tools. Thus, it is challenging to understand the complex biology of mosquitoes which popularize themselves as the most dangerous animals on earth (https://www.statista.com/chart/2203/the-worlds-deadliest-animals/). Disease transmission by mosquitoes is restricted to the blood-feeding behavior of adult female mosquitoes which takes blood meal from humans and other vertebrate hosts for the completion of their gonotropic cycle. In order to carry out the successful blood-feeding event, the integration of the "olfactory system," the receiver of the chemical/environmental stimuli; the "central nervous system," the hardware system with high processing efficacy; and the "salivary gland," the output/feedback device are obligatory. Here we provide an overview and update the current knowledge on how the sensory system of mosquito detects essential chemical information which are then processed by the central nervous system for successful navigation and

stimulate the salivary gland for salivation to facilitate the feeding event.

Feeding is a fundamental need of every animal to achieve their optimal growth, survival, and reproductive requirements. But the strategy of food intake and the feeding preference largely vary depending on the internal metabolic needs, i.e., whether they are starved or satiated; on the internal physiological state, i.e., whether they are virgin or mated and gravid or unfed; and also on the external sensory stimuli. In the case of mosquitoes, plant sugars such as nectar and honeydew are the primary energy source for survival, flight, and foraging activities of both males and females. Only adult female mosquitoes take blood meal as an optional dietary supplement, and this specialization is predicted to evolve for better fitness [7–9]. Genetic architecture and the allelic polymorphism of different mosquito species influence their traits towards selection and preference for feeding hosts. Apart from that other internal factors such as circadian rhythm and physiological status including nutritional and mating status, as well as environmental factors such as temperature and humidity, affect mosquito

Each feeding event of mosquitoes is initiated by random navigation from a long distance, which becomes specific when triggered by a certain group of chemicals such as CO2, lactic acid, 1-Octen-3-Ol, acetone, ammonia, etc. The detection of other additional cues such as visual and thermal factors facilitates the downstream events of host localization, landing over the host and searching for a suitable site for probing by the proboscis to initiate blood-feeding. But, successful navigation does not always corroborate with a successful feeding event, because it involves another level of regulation of the central nervous system by discriminating the

**74**

*Factors affecting mosquitoes' feeding behavior. The genetic structure, circadian cycle, mating status, internal nutritional status, and external environmental factors such as temperature and humidity cumulatively work to shape the mosquitoes' feeding preference toward either sugar meal or blood meal. The internal nutritional status is dependent on larval nutrition, the amount of nutrient storage, and the feeding condition of the mosquito, i.e., either starved or satiate.*

#### **Figure 2.**

*The path of signal processing for achieving successful mosquito navigation and feeding. The tripartite interorgan communication among three tissues, viz., olfactory tissue, central nervous system (brain), and the salivary gland, is crucial for the completion of feeding events. The olfactory tissue (highlighted by purple circle) senses and binds to odor molecules emanating from either plant or vertebrate host and sends the respective signal towards the brain system (highlighted as yellow circle). After processing the initial signal of odor in the central nervous system, the decision-making process occurs, and then the brain sends the signal towards the salivary gland (highlighted as red circle), and the process of salivation started to facilitate feeding. Photo credit goes to Zwiebel Lab, Vanderbilt University, for the olfactory system of* Anopheles *mosquito. The salivary gland picture was taken from the research article by Ghosh et al. [12].*

odor molecules and making a decision for either to feed or not. Post landing and piercing on a particular site of the vertebrate host, successful uptake of blood meal largely depends on the proper functioning of the salivary gland which acts as the final action machinery by facilitating the feeding process through salivation. Thus, here we provide a detailed integrative description of (1) how mosquitoes detect

and discriminate among odorant molecules through olfactory system, (2) how the initial signal of odor is processed in the central nervous system/brain and the molecular factors responsible for feeding decision-making process, and (3) how the brain influences and regulates distant tissue such as salivary gland for salivation and consequently helps in food acquisition (**Figure 2**).
