**1. Introduction**

Mosquitoes that belong to the order Diptera and Culicidae family account for large biomass of insects' community and are one of the most notorious animals on earth which transmit many blood-borne pathogens. It is only the adult female mosquitoes which bite on human and other vertebrate hosts to access the blood and thus have strong impact on epidemiological consequences. So far about 3540 species of mosquitoes have been recognized that are divided into 2 subfamilies and 112 genera [1] which are inhabiting throughout the temperate and tropical regions. *Anopheles* species biodiversity and species richness seem to be one of the dominantly evolved blood-feeding insect species race on earth, impacting millions of lives through transmitting deadliest disease malaria around the globe. In tropical areas, *Anopheles gambiae*, *Aedes aegypti*, and *Culex quinquefasciatus* are the most notorious mosquito vectors of infectious diseases such as malaria, dengue, and filariasis, respectively. The main causative agents of malaria are *Plasmodium falciparum* and *Plasmodium* 

*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.
