ARTHROPODSARTHROPODS

Classification Classification

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General CharacteristicsGeneral Characteristics

Doç.Dr.Hrisi BAHARDoç.Dr.Hrisi BAHAR

Phylum Phylum ArthropodaArthropoda(jointed  feet ) 

The arthropods are:The arthropods are:● The most successful phylum of

animals, both in diversity of distribution and in numbers of species and individuals.

● They have adapted successfully to life in water, on land and in the air.

● About 80% of all known animal species belong to the Arthropoda - about 800,000 species have been described.

● They can survive great extremes of temperature, toxicity, acidity and salinity.

Characteristics of Arthropoda ● Metamerism- body is segmented.

● Exoskeleton- body covered with a hard

external skeleton.

● Bilateral Symmetry- body can be divided

into two identical halves.

Characteristics of Arthropoda

Jointed Appendages- each segment may have one pair of appendages, such as:

● legs

● wings

● mouthparts

●Open Circulatory System- blood washes over organs and is not entirely closed by blood vessels. Our system is a closed one

●Ventral Nerve Cord- one nerve cord, similar to our spinal column

Some of the arthropods are ectoparasite.

● Ectoparasite: arthropod living outside the human body

Some Common Ectoparasites

● Common bedbugs (Cimex lectularius)

● Human fleas (Pulex irritans)

Some of the arthropods are ectoparasite.

● Ectoparasite: arthropod living outside the human body

Some Common Ectoparasites

● Common bedbugs (Cimex lectularius)

● Human fleas (Pulex irritans)

Classes of Medical Importance

Subphylum CRUSTACEAE   Two Class are medically

important

● Class Arachnida 

● Class Insecta

Class insecta

● The insects are the most numerous and diverse of all the groups of arthropods. There are more species of insects than species in all the other classes of animals combined.

 

Class insecta

● Insects differ from

other arthropods in

having three pairs of

legs. In size, insects

range from less than 1

mm to 20 cm in length,

the majority being less

than 2.5 cm long.   

Characteristics of Insecta

1- 3 body segments-  head, thorax chest),  abdomen (stomach area). 2- One pair of antennae 3- Tracheal Respiratory System- composed of

tubes, with holes (spiracles) through the body that admit air. So, they do not have lungs at all.

Characteristics of Insecta

4- Wings- usually two pairs of wings, although some have one pair of wings, or none.

No other class of arthropods has wings

5- 3 pair of legs, 1pair to each of the 3 thoracic segments. Compound eyes, with facets

● Kingdom Animalia (Animals)

● Phylum Arthropoda (Arthropods)

● Class Insecta (Insects)

● Order Diptera (Flies)

Flies

The larvae of flies.

Flies are common in the warmer months, and love dead, stinky, and rotting material. They lay eggs, and the eggs develop into larvae (maggot) that need to eat. They appear quite fast (8-12 hours), and will eat away tissue if the conditions are present

Flies

● vomit, diarrhea, skin infection (blood, pus), poor skin/matted hair attract these pests. This condition can occur in all animals, including humans.

Maggots are also used medicinally to clean up (debride) wounds, but only under very controlled conditions.

Myasis

Disease that results from the infestation of tissues or cavities of the body by larvae(maggots) of flies

Myasis

There are three main fly families causingEconomically important myiasis in livestock and also, occasionally, in humans:

1- Oestroidea

(Cuterebra sp)2- Calliphorideae

(ex:Caliphora sp, ex:Lucilia sericata)3- Sarcophagidae

(ex:Sarcophaga sp)

Lucilia sericata

Sarcophaga sp

Caliphora sp

Anopheles

Scientific classification● Kingdom:Animalia

● Phylum:Arthropod

● Class:Insecta

● Order:Diptera

● Family:Culicidae

● Genus:Anopheles

Life Stage

● Eggs

● Larvae

● Pupae

● Adults

Anopheles

● Anopheles is a genus of mosquito (Culicidae).

● There are approximately 460 recognised species: while over 100 can transmit human malaria, only 30-40 commonly transmit parasites of the genus Plasmodium that cause malaria which affects humans in endemic areas.

● Anopheles gambiae is one of the best known, because of its predominant role in the transmission of the deadly species –Plasmodium falciparum.

● Some species of Anopheles also can serve as the vectors for Filariidae Wuchereria bancrofti

● Mosquitoes in other genera (Aedes,Culex) can also serve as vectors of disease agents.

Anopheles gambiaeAnopheles gambiae

Eggs

● Adult females lay 50-200 eggs per oviposition. Eggs are laid singly directly on water and are unique in having floats on either side.

● Eggs are not resistant to drying and hatch within two-three days, although hatching may take up to two-three weeks in colder climates.

Larvae

● Mosquito larvae have a well-developed head

with mouth brushes used for feeding.

● A large thorax and a segmented abdomen. They don't have legs.

.

Larvae

● In contrast to other mosquitoes, Anopheles larvae lack a respiratory siphon and for this reason position themselves so that their body is parallel to the surface of the water.

● Larvae breathe through spiracles located on the 8th abdominal segment.

Pupae

● The pupa is comma-shaped when viewed from the side.

● The head and thorax are merged into a cephalothorax with the abdomen curving around underneath.

● As with the larvae, pupae must come to the surface frequently to breathe, which they do through a pair of respiratory trumpets on the cephalothorax.

● After a few days as a pupa, the dorsal surface of the cephalothorax splits and the adult mosquito emerges.

Adult

● Like all mosquitoes, adult Anopheles have slender bodies with 3 sections:

head, thorax and abdomen.

● The head contains the eyes and a pair of long, many-segmented antenna.

● The head also has an elongated, forward-projecting proboscis used for feeding, and two sensory palps.

● The currently known vectors for human malaria (>100 species) all belong to the genus Anopheles

● When a person becomes infected with one of the

Plasmodium parasites that cause malaria, he or she will not feel sick immediately. The infected person may feel normal from seven days to several years after infection; however, inside his or her body, the malaria parasites are multiplying.

● The period between infection with the parasites that cause the disease and the beginning of malaria symptoms is called the malaria incubation period.

● The incubation period for the disease typically lasts between 10 days to four weeks. In some cases, the malaria incubation period may be as short as seven days or as long as several years.

● Factors that affect the incubation period for malaria include the type of Plasmodium parasite responsible for the infection.

● Plasmodium falciparum tends to have a shorter incubation period, while Plasmodium malariae

tends to have a longer incubation period.

. ● Plasmodium vivax and Plasmodium ovale, can have a much longer malaria incubation period. For these parasites, a proportion of them may begin to grow immediately in the liver and cause symptoms after the normal incubation period. The remaining portion may remain inactive ("dormant") in the liver for several months (and up to about four years) after a person is bitten by an infected mosquito.

When these parasites come out of hibernation, begin multiplying and then invade red blood cells, the person will become sick again. These "sleeping" forms are the causes of the relapses seen with these two species.

When antimalarial drugs are used to prevent the spread of the disease, they may also increase the length of the malaria incubation period by weeks or months.

There are essentially 3 targets for malaria control: ● The human host

● The parasite ● The vector.

Vector control is the main focus of public health efforts,

and can be broken down into 4 major types of control,

summarized below.

4 major types of malariae control

● Control by personal protection

● Control by environmental management

● Control by chemical (Insecticides)

● Other measures like biological control, genetic control, zooprophylaxis

Culex

●Is a genus of mosquito, and is important in that several species serve as vector of important diseases such as West Nile Virus, filariasis Japanese encephalitis, St.Louis encephalitis and avian malariae.

● The most important of the Culex vectors are members of the Culex pipiens complex.

● Culex pipiens is the house mosquito Disease is spread by females. Males do not bite .

Scientific classification

Kingdom:AnimaliaPhylum:ArthropodaClass:InsectaOrder:DipteraFamily:CulicidaeGenus:Culex

Life Stage

● Eggs

● Larvae

● Pupae

● Adults

● The developmental cycle of culex takes two weeks and is by complete metamorphosis

● Eggs are laid singly or in batches, depending on the species. Eggs will only hatch in the presence of water.

Larvae

During the larval stage the mosquito lives in water and feeds on organic matter and plants. All larval stages are aquatic; collectively they take from 7 to 14.The presence of a moderately long siphon is a characteristic of larvae

Pupa

The pupa is commshaped and alsolives in water. Itdoes not feed andbecomes an adultafter one or twodays.

Adult culex

Adults of the Cx. pipiens complex are light brown mosquitoes that lack distinctive markings on the proboscis and legs, and are not readily separated from other Culex (Culex) mosquitoes. Adult females of the complex are usually identified by the presence of distinctive, basal, pale abdominal bands.

Disease is spread by females. Males do not bite. The females take blood meals that are used to support the development of eggs. Culex is described as zoophagic because it takes its meals from animals as well as humans and can also be described as ornithophagic because it frequently feeds on birds

*culex

Any disease that is carried by Culex can

therefore become difficult to eradicate because any animal community that it feeds on can become a reservoir and mobile species, such as birds, can spread the disease through a large area. This was seen in 1999 in the Eastern United States when West Nile virus was introduced into the area. Culex pipiens feeds at night.

*culex

Phlebotomus(Sandfly)

Scientific classification

Kingdom:AnimaliaPhylum:ArthropodaClass:InsectaSubclass:PterygotaSuperorder:EndopterygotaOrder:DipteraFamily:PsychodidaeSubfamily:PhlebotominaeGenus:Phlebotomus

Life StageLife Stage

●●EggsEggs ● ●LLarvaearvae ● ● AdultsAdults

Phlebotomus(Sandfly)

In the old world Phlebotomus sand flies are

primarily responsible for the transmission

of leishmaniasis an important parasitic

disease, while transmission in the new

world, is generally via sand flies of the

genus Lutzomyia.

Phlebotomus(Sandfly)

The female sand fly carries the Leishmania protozoa from infected animals after feeding, thus transmitting the disease, while the male feeds on plant nectar.

Phlebotomus species are also vector for

phlebotomus fever, an arbovirus caused by Toscana virus.

Phlebotomus(Sandfly) Females lay eggs which are dark

and rich in organic matter.

They are small, elliptical and brownish in colour.

Hatching occurs into the larval stage. Larvae are small whitish in colour with a black head capsule. From the posterior end arise a pair of long, dark caudal bristles which are characteristic for this species.

Adults are small sized

about 1.5-3 mm, yellowish

in colour with

conspicuous black eyes,

hairy body, wings and

legs.

Phlebotomus(Sandfly)

The oval lanceolate wings are carried erect

on the humped thorax.

Males possess long prominent genital

terminalia known as claspers.

Females have a pair of anal recti

Phlebotomus(Sandfly)