**3. The adaptability of the** *Anopheles* **mosquitoes**

Malaria is a problem in the tropics and not in temperate regions of the world. In the temperate countries, there are mosquitoes, but the life of the malaria parasite inside the mosquito is a race against time. The time taken for the malaria parasite to go through its growth and development is close to the average life span of the mosquito itself. This period is longer in the temperate areas where the survival of the parasite is on the knife edge, and temperature below certain point reduces the life span of the mosquito before it can transmit malaria [6].

The adaptability of *Anopheles* mosquitoes in the tropics and the ability to thrive in variety of habitats are a big challenge, and this is tantamount to greater spread of malaria.

Mosquitoes naturally infest ponds, marshes, puddles, swamps, and other wetland habitats. However, mosquitoes can also breed in any collection of still or stagnant waters [7].

Adult female mosquitoes may live up to a month in extreme cases in captivity but up to 2 weeks in nature. They are poikilothermic and have amazing adaptability such as suctorial mouthparts, holometabolous life cycle, and great diversity which are some of the secrets behind their success [8].

Both male and female *Anophele*s mosquitoes feed on sugary and plant juices as source of energy, flight, and dispersal. However, only the female mosquitoes feed on blood which is required every 2–3 days for the maturation of its eggs as the plant sources are inefficient. This blood sucking instinct is a mandatory biological process [9]. Female mosquitoes mate once in a lifetime and require still waters to oviposit. Mosquito goes through four stages during its life cycle. The first three stages egg, larva, and pupa are aquatic, but the adult is aerodynamic but may also rest on vegetation. More so, in Africa, malaria-carrying mosquitoes typically bite between dusk and dawn which coincides with the sleeping patterns of the people [3, 6].

#### **3.1 The environment and the human malaria vectors**

Distribution and incidence of vector-borne diseases are determined by the ecological conditions that favours them [10]. There is a relationship between the environment and mosquito abundance [11]. There are evidences that mosquito can adapt to environmental changes and even water pollution [12]. Today's mosquito breeds even where we thought they can never thrive due to environmental changes [9]. It has been established that climatic factors have profound influences on mosquito's life span [13]. As ecosystems are being modified across the planet, the habitat is altered, and malaria territories are being extended because of global warming.

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*Nipping the Malaria Vectors in the Bud: Focus on Nigeria*

Consequently, any small variations in microclimate can affect the mosquito's

These include factors such as temperature, rainfall and humidity which are important factors for mosquito development, and longevity [15]. Changes in the local environment are important as they create or reduce the number of suitable breeding sites for vectors, so affecting their abundance and transmission pattern [16]. Temporal and spatial changes in temperature, precipitation, and humidity under different climatic conditions will affect the biology and ecology of malaria

This factor has been regarded to be the most important factor affecting mosquitoes [17, 18]. A drop in temperature can change a mosquito's life span by more than 1 week. Small changes in temperature result in large differences in availability and development of mosquitoes. This implies that if temperature rises, the larvae takes a shorter time to mature and more offspring are produced. In fact, temperature affects metamorphic changes of mosquitoes in their breeding water sites [18]. This also means that the frequency of sucking and digesting of blood meal by female mosquitoes increases, and this has grave implications for malaria transmission [17].

This factor also plays a role in mosquito ecology as it increases the availability of surface water and so more breeding sites and affects relative humidity and hence longevity of the adult mosquito [6]. There is relatively lower temperature but higher relative humidity. Biting intensity of mosquito reduces as rainfall reduces and can be suspended at low temperature. Rainfall also determines the type of predominant malaria vector species. For example, *An. arabiensis* prevails in the dry season, while

Mosquitoes will rest in houses after feeding if there is no outdoor resting site. Vegetation increases outdoor resting sites and mosquito abundance, and type of species could relate to type of vegetation cover [19]. For example, it has been reported that *Anopheles arabiensis,* a malaria vector in Nigeria, predominates in the arid savanna, while *An. gambiae ss* is a forest-loving vector. *An. arabiensis* has been

Malaria is the most widespread mosquito-borne disease in Nigeria where it has a holoendemic status, the most vulnerable groups being children aged 0–5 years and pregnant women [3]. The disease accounts for 25% of infant mortality and 30% of childhood mortality [2]. Nigeria contributes the highest burden to global malaria morbidity and deaths. This is about 25% of global malaria cases, about 30% of

identified in deforested areas within forested areas in urban areas [6, 9].

**4. The challenges of malaria vector control in Nigeria**

vectors and consequently the risk of malaria transmission [15].

*An. gambiae sensu stricto* (ss) is a rainy season vector [8, 9].

*DOI: http://dx.doi.org/10.5772/intechopen.83554*

chances of survival or longevity [14].

*3.1.1 Environmental factors*

*3.1.2 Temperature*

*3.1.3 Rainfall*

*3.1.4 Vegetation*

**4.1 Human malaria in Nigeria**

Consequently, any small variations in microclimate can affect the mosquito's chances of survival or longevity [14].
