Mosquitoes serve as vectors for deadly diseases like malaria, transmitting pathogens from infected hosts to new hosts. The paper discusses mosquito vector behaviour and implications for disease transmission, covering the lifecycle from egg to adult, habitats and breeding sites, feeding and host preferences, and implications for control. It explores how factors like temperature and precipitation impact mosquito and disease seasonality and distribution globally.

1. MOSQUITO VECTOR BEHAVIOUR;IMPLICATIONS FOR TRANAMISSION
BEING A SEMINAR PAPER SUBMITTED TO THE DEPARTMENTOF ZOOLOGY
PRESENTED BY:
TACHIN FAITH MATRIC NO: 17/44174/UE
DEPARTMENT OF ZOOLGY
JOSEPH SARWUAN TARKAUNIVERSITYMAKURDI,
IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARDOF BACHELOR OF SCIENCE (B.SC) DEGREE IN ZOOLOGY

2. Overview of study
SUMMARY
A vector is an organism that does not cause disease itself but spreads infection by conveying pathogens from one host to another. Some Species of mosquito, for example,
serve as vectors for the deadly disease such as Malaria (Wilson et al, 2017).
Disease is any harmful deviation from the normal structural orfunctional state of an organism, generally associated with certain signs and symptoms and differing in nature
from physical injury.
A diseased organism commonly exhibits signs or symptoms indicative of its abnormal state. Mosquitoes are common, flying insects that live in most parts of the world.
Over 3,500 types of mosquitoes can be found worldwide (Hardstone et al, 2012).Not all mosquitoes bite people or animals.
When mosquitoes bite people, the most common reactions to the bite are itching and swelling. Some mosquitoes can be vectors. The germs (viruses and parasites) that
mosquitoes spread can make people sick. Some mosquitoes bite, but do not spread germs. These types of mosquitoes are called nuisance mosquitoes (Becker et al, 2010).

3. Facts about Mosquitoes
Adult mosquitoes live indoors and outdoors.
Mosquitoes can bite day and night.
Mosquitoes live for about 2 to 4 weeks depending on the species, humidity, temperature, and other factors. Female mosquitoes often live longer than
male mosquitoes.
Only female mosquitoes bite people and animals to get a blood meal. Female mosquitoes need a blood
meal to produceeggs.
Mosquitoes get infected with germs, such as viruses and parasites, when they bite infected people and
animals.
It takes just a few infected mosquitoes to start an outbreak in a community and put you and your family at risk of becoming sick.

4. Morphology
As true flies, mosquitoes have one pair of wings, with distinct scales on the surface. Their wings are long and narrow, as are their long, thin legs. They have slender and
dainty bodies of length typically 3–6 mm, with dark grey to black coloring. Some species harbor specific morphological patterns. When at rest they tend to hold their first
pair of legs outward. They are similar in appearance to midges (Chironomidae)
Habitats
Some mosquitoes like living near people, while others prefer forests, marshes, or tall grasses. All mosquitoes like water becausemosquito larvae and pupaelive in the water
with little or no flow. Different types of water attract different types of mosquitoes.
Permanent water mosquitoes: These mosquitoes tend to lay their eggs in permanent-to- semi-permanent bodies of water (Knight et al, 2003).
Some mosquitoes prefer clean water, while others like nutrient-rich waters. Some mosquitoes lay eggs near the edges of lakes and ponds, or among plants in swamps and
marshes, or in containers that hold water (Knight et al, 2003).

5. Habitats
Floodwater mosquitoes: These mosquitoes lay their eggs in moist soil or in containers above the water line. The eggs dry out, then hatch when rain floods the soil or
container. Floodwater habitats include:
Temporarypools and ponds created by melting snow orrain
Floodplains along stream and river banks
irrigated fields and meadows
Containers that hold water and fill up after a rain shower and tree holes that collect rainwater
Breeding
In most species, adult females lay their eggs in stagnant water: some lay near the water's edge while others attachtheir eggs to aquatic plants. Each species selects the
situation of the water into which it lays its eggs and does so according to its own ecological adaptations. Some breed in lakes, some in temporary puddles. Some breed in
marshes, some in salt-marshes. Among those that breed in salt water, some are equally at home in fresh and salt water up to about one- third the concentration of seawater,
whereas others must acclimatize themselves to the salinity (Day 2015). Such differences are important because certain ecological preferences keep mosquitoes away from
most humans, whereas other preferences bring them right into houses at night. Some species of mosquitoes prefer to breed in phytotelmata (natural reservoirs on plants),
such as rainwater accumulated in holes in tree trunks, or in the leaf-axils of bromeliads (Ahmed, 2013).

6. Anatomy of an adult mosquito
The period of development from egg to adult varies among species and is strongly influenced
by ambient temperature. Some species of mosquitoes can develop from egg to adult in as few
as five days, but a more typical period of development in tropical conditions would be some
40 days or more for most species. The variation of the body size in adult mosquitoes depends
on the density of the larval population and food supply within the breeding water (Brittain,
1990).
Adult mosquitoes usually mate within a few days after emerging from the pupal stage. In most
species, the males form large swarms, usually around dusk, and the females fly into the swarms
to mate. Males typically live for about 5–7 days, feeding on nectar and other sources of sugar.
After obtaining a full blood meal, the female will restfor a few days while the blood is digested
and eggs are developed. This process depends on the temperature, but usually takes two to
three days in tropical conditions. Once the eggs are fully developed, the female lays them and
resumes host-seeking (Brittain, 1990).

7. INTRODUCTION CONT’D
Feeding by adults
Typically, bothmale and female mosquitoes feed on nectar, aphid honeydew, and plant juices, but in many species the mouthparts of the females are adapted for piercing the
skin of animal hosts and sucking their blood as ectoparasites. In many species, the female needs to obtain nutrients from a blood meal before it can produceeggs, whereas
in many other species, obtaining nutrients from a blood meal enables the mosquito to lay more eggs. A mosquito has a variety of ways of finding nectar or its prey, including
chemical, visual, and heat sensors (Krenn, 2019). Both plant materials and blood areuseful sources ofenergy in the form ofsugars, and blood also supplies more concentrated
nutrients, such as lipids, but the most important function of blood meals is to obtain proteins as materials for egg production.

8. Mouthparts
Mosquito mouthparts are very specialized, particularly those of the females, which in most species are adapted to piercing skin and then sucking blood. Apart from
bloodsucking, the females generally also drink assorted fluids rich in dissolved sugar, such as nectar and honeydew, to obtain the energy they need. For this, their blood-
sucking mouthparts are perfectly adequate. In contrast, male mosquitoes are not bloodsuckers;they only drink sugary fluids. Accordingly, their mouthparts do not require
the same degree of specialization as those of females. (Davies et al; 2008)

9. Egg development and blood digestion
Most species of mosquito require a blood meal to begin the process of egg development. Females with poor larval nutrition may need to ingest sugar or a preliminary blood
meal bring ovarian follicles to their resting stage. Once the follicles have reached the resting stage, digestion of a sufficiently large blood meal triggers a hormonal cascade
that leads to egg development (Telanget al., 2006). Upon completion of feeding, the mosquito withdraws her proboscis, and as the gut fills up, the stomach lining secretes
a peritrophic membrane that surrounds the blood.

10. Distribution
 Mosquitoes are cosmopolitan (world-wide): they are in every land region except Antarctica and a few islands with polar or subpolar climates. Iceland is such an
island, being essentially free of mosquitoes. The absence of mosquitoes from Iceland and similar regions is probably because of quirks of their climate, which differs in
some respects from mainland regions. At the start of the uninterrupted continental winter of Greenland and the northern regions of Eurasia and America, the pupa enters
diapause under the ice that covers sufficiently deep water. Ujváry, (2010).
 The imago emerges only after the ice breaks in late spring. In Iceland however, the weather is less predictable. In mid-winter it frequently warms up suddenly, causing
the ice to break, but then to freeze again after a few days.

11. Climate andglobaldistribution
Seasonality
In order fora mosquito to transmit a disease to the hostthere must be favorable conditions, referred to as transmission seasonality. Seasonalfactors that impact the prevalence
of mosquitos and mosquito-borne diseases are primarily humidity, temperature, and precipitation. A positive correlation between malaria outbreaks and these climatic
variables has been demonstrated in China; and El Niño has been shown to impact the location and number of outbreaks ofmosquito-borne diseases observed in East Africa,
Latin America, Southeast Asia and India.
Climate change impacts each of these seasonal factors and in turn impacts the dispersal of mosquitos
Karungu et al., (2019)
Mosquito-borne diseases
Mosquitoes canact as vectors for many disease-causing viruses and parasites. Infected mosquitoes carry these organisms from person to person without exhibiting symptoms
themselves. Mosquito-borne diseases include: Viral diseases, such as yellow fever, dengue fever, and chikungunya, transmitted mostly by Aedes aegypti. Dengue fever is
the most common cause of fever in travelers returning from the Caribbean, Central America, South America, and South CentralAsia.
This disease is spread through the bites of infected mosquitoes and cannot be spread person toperson.

12. MosquitoFeeding
Blood feeding in mosquitoes follows a species-specific circadian rhythm, which is mainly nocturnal.
Generally three main categories can be distinguished:
Nocturnal, if feeding occurs atnight – many, probablymost species belong to this group, e.g. some Aedes species and Mansonia africana;
Diurnal, if feeding occurslargely during daylight hours, e.g. Aedes apicoargenteusand Aedes longipalpis;and
Crepuscular, if feeding occurslargely during twilight hours, at dusk or at dawn,
e.g. Aedes africanusand Anopheles gambiae (Goma, 1966 Lazzari, et al., (2019).

13. The feeding habits include:
Feeding habits
Anthropophagic/anthropophilic: mosquitoes biting (preferably) humans
Zoophagic/zoophilic: mosquitoes biting lifestock and other animals
Endophagic: mosquitoes biting mainly inside houses
Endophilic: mosquitoes resting indoors after blood-feeding while the meal is digested and the eggs mature
Exophagic: mosquitoes biting mainly out of doors
Exophilic: mosquitoes resting outdoors after blood-feeding while the meal is digested and the eggs mature
Female mosquitoes bite because they need protein found in blood to develop their eggs. They choose their targets through a combination of smell, heat and visual cues, and
continue seeking blood meals until their abdomens are full. The females can live up to about a month and feed every two or three nights during that time. The mostcommon
mosquito species feed at dawn and dusk, and for a few hours into dark. However, there are some species that are particularly aggressive and will feed both day and night
(Baptista et al., 2007)

14. Hostspectrum
 Mosquitoes obtain their blood meals froma very wide variety of hosts. Theseinclude warm-blooded animals as birds, cattle, pigs, numerous wild animals, and humans;
and cold-blooded animals such as frogs, lizards, snakes, insect nymphs and pupae. The choice of host varies greatly with species of mosquito and the availability.
 Many species have a marked predilection for one type of host which they select if reasonable available, taking other hosts only in the absence of their preferred food
(Macdonald, 1957). Other mosquitoes have no particular preferences and will feed readily on a wide range of hosts.

15. Mosquitocontrol
Mosquito fish Gambusia affinis, a natural mosquito predator
 Many measures havebeen tried formosquito control, including the elimination of breeding places, exclusionvia window screens and mosquito nets , biological control
with parasites such as fungi and nematodes, or predators such as fish, Copepods, dragonfly nymphs and adults, and some species of lizard and gecko.
Another approach is to introduce large numbers of sterile males.

16. CONCLUSION
In summary, the study shows mosquito lifecycle, its habits, breeding sites, the disease they transmit and its resting behaviour after blood meal.
Attribute such as host spectrum. The study also involves the control of the vector using the natural means (mosquitofish Gambusia affinis), elimination of breeding sites
and chemical control methods such as use of insect repellent (DEET) and the use of treated nets.

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