Mosquito Biology and Emerging Health Issues


Seminar Paper, 2018

11 Pages, Grade: 1.1


Excerpt

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Introduction
Mosquitoes remain to be among the most amazing organisms in the universe. Evolutionary data reveals
that mosquitoes have survived for more than 30 million years in which 3,500 species have evolved. Despite
the large genetic diversity observed in mosquitoes, only a few species have been found to bother humans.
Over the years, research on mosquitoes has enabled entomologists in identifying different mosquito
taxonomic classes. However, the classification of mosquitoes has been surrounded by unprecedented
controversy because new species are being discovered year-by-year. The latest mosquito species to be
identified include the two mosquito species belonging to the Topomyia genus recently discovered in Sri
Lanka and the invasive Aedes japonicas species discovered in Asia (Kampen & Werner 2014).
According to the taxonomic classification, mosquitoes belong to the largest animal phylum; Arthropoda, and
they are grouped in the Class: Insecta that comprises of other insects such as the flies. Down in the
taxonomic classification, mosquitoes belong to the Order: Diptera and Family: Culicidae that comprise of
various sub-families. At present, there are 43 known mosquito genera, which comprise of over 3,500
species (Rueda 2008).
In addition, an extensive study has been conducted to generate a comprehensive understanding on the
anatomy, physiology and ecological characteristics of mosquitoes. It is believed that the ecological
characteristics of mosquitoes and physiology are responsible for the emerging health issues. Therefore,
this research paper will give a comprehensive overview of the mosquito biology. It will discuss the anatomy,
physiology and ecological characteristics of mosquitoes. It will also provide a concise overview on the
mosquito-borne diseases.
Mosquito Anatomy
Mosquitoes are two-winged insects with a small body which is divided into three principal body parts: the
head, thorax and the abdomen (Byrd & Castner 2000). These body parts exhibit diverse anatomical
features which define their biological functions. In general, an adult mosquito has a slender abdomen, and

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adults vary in length. Different mosquito species have different body lengths although their average length
is estimated to be 6 mm, and 2.5 milligrams in weight.
Figure: Mosquito body regions (University of Florida 2008 p.1-2)
Mosquitoes have a crammed head that contains sensory apparatus. These structures are believed to be
the most significant anatomical features that define the feeding mode of mosquitoes. Some of the most
significant anatomical apparatus found on the head region of mosquitoes are the eyes, antenna and the
mouth parts. The two large compound eyes comprise of tiny lenses referred to as ommatidia which are
concerned with the detection of movements. In addition to these sensory lenses in the compound eyes,
mosquitoes possess simple photosensitive eyes known as the ocelli which are located on the top of their
heads (Arikawa, Kawada, Takagi & Tatsuta 2006). These simple eyes are capable of detecting variations in
light; thus, enabling mosquitoes in identifying their habitats.
The other sensory structures that are found on the head region are the antenna. The antennae are long
feathery sensory organs that elongate forward from the head, and they contain sensitive receptors which
enable mosquitoes to locate food sources. These receptors can detect chemicals such as carbon dioxide in
human breath from as far as 100 feet. In addition, mosquitoes have other sensory structures such as the

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maxillary palp that is located between the antennae. This sensory apparatus is capable of detecting
chemicals in the human sweat including urea and ocentol (Carde, Dekker & Geier 2005).
They also have a long serrated proboscis which holds the stylets used in piercing the skin and sucking
blood. One of the tubes injects saliva into the animal's body from which the insect gets its blood meal,
whereas the other stylet draws blood from the animal's blood vessels that lie underneath the skin (Kim, Kim
& Lee 2010).
On the other hand, the thorax comprises of the appendages involved in the movement and locomotion of
mosquitoes. The thorax in a torso connected to the head and it bears the three pairs of legs with tiny claws
for grasping on surfaces and a pair of wings for flying. In addition to the wings, there are other small wing-
like structures known as halteres which are used for steering during flight (Aldworth, Daniel, Fox &
Hinterwirth 2012).
The slender abdomen hangs from the thorax, and it contains the digestive tract and respiratory structures.
As such, it serves as the stomach; thus, it holds the blood meal. It also stores eggs in female mosquitoes.
On the other hand, the abdomen contains small openings referred to as spiracles which are used for
gaseous exchange.
In general, anatomical characteristics of mosquitoes are considered crucial in the taxonomic classification
of mosquito species. For instance, the length of wings and the maxillary palp, as well as, the coloring and
shape of the abdomen are used in identifying different species of mosquitoes.
Physiology in Mosquitoes
Physiological processes in mosquitoes exhibit differences among the species, although some of these
differences are attributable to the adaptation of mosquitoes to various habitats and feeding modes.
Ordinarily, growth and development in mosquitoes involve three distinct stages which characterize their
lifecycle. Mosquitoes' development is more or less the same as that observed in other holometabolous
insects in which development involves the egg, larva, pupa and adult stages. Female mosquitoes lay eggs

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in aquatic environments through a process known as oviposition where they hatch into larval forms (Briegel
2003). The larva develops into a pupae form which in turn grows into adults in which males live for than a
week whereas female mosquitoes have a lifespan of several weeks, especially in an environment with
adequate supply of food sources.
Digestion in mosquitoes exhibits several characteristics that enable them to survive on their mode of
feeding. Mosquitoes rely on plant juices and nectar as their principal sources of food, although female
mosquitoes require a blood meal from birds and mammals for the development of eggs. It is worth noting
that, male mosquitoes do not feed on blood as their female counterparts; instead, they feed on sugary plant
juices for their nutrition. In female mosquitoes, blood is sucked from the animal skin through the use of a
proboscis. During feeding, a mosquito injects anti-coagulant containing saliva into the host's tissue fluid and
draws it into the gut where digestive enzymes including proteases breakdown the blood meal for
absorption. Thereafter, waste products that include uric acid are excreted through the anus.
Gaseous exchange in mosquitoes occurs through the tracheal system which comprises of the spiracles
located on both sides of the abdomen. The tracheal system contains end bulbs or air sacs which are in
contact with the coelomic fluids in the surrounding body tissues. Therefore, respiratory gases, oxygen and
carbon dioxide enter and leave the tracheal system through diffusion in which oxygen is taken up for
respiration and carbon dioxide exhaled as a by-product.
Moreover, mosquitoes have an elaborate endocrine system that controls the release of hormones. These
hormones are believed to play a significant role in defining the behavior of mosquitoes.
Ecological Role of Mosquitoes
Distribution of Mosquitoes
From an ecological perspective, mosquitoes exhibit a widespread distribution in which they colonize all
ecological zones except the Antarctica region. Ordinarily, mosquitoes are abundant in the tropical regions
which are characterized by warm and humid climatic conditions. These climatic conditions are favorable for
Excerpt out of 11 pages

Details

Title
Mosquito Biology and Emerging Health Issues
College
Egerton University
Grade
1.1
Author
Year
2018
Pages
11
Catalog Number
V388323
ISBN (eBook)
9783668627079
ISBN (Book)
9783668627086
File size
433 KB
Language
English
Tags
mosquito, biology, emerging, health, issues
Quote paper
Patrick Kimuyu (Author), 2018, Mosquito Biology and Emerging Health Issues, Munich, GRIN Verlag, https://www.grin.com/document/388323

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