Difference between revisions of "Insecta"

Revision as of 15:34, 26 October 2008

Classification

Arthropod Classification - copyright nabrown RVC

The phylum arthropoda is divided into several subphylums including Chelicerata (which includes the arachnids), Myriapoda, Hexapoda (which includes the insecta), Crustacea and Trilobitomorpha. These are then divided into many classes. The two of major veterinary importance are the insecta and arachnida classes.

Structure and Function

Insect Body

Covered by an exoskeleton secreted by underlying epidermis

Divided into head, body and abdomen

Insect Head

Capsule of fused plates at the anterior end of the body

One large pair of compound eyes
- Honeycomb like corneal facets

Three simple ocelli
- Dorsal to compound eyes

One pair of antennae

Antennae

Form varies amongst insecta
- E.g. long and segmented, short and squat etc.

Hairs sometimes present

Aristae (bristles) sometimes present

Mouthparts

Modification depending on feeding method

Insects which suck up liquified food have an expanded sponge like labellae
- Cannot penetrate skin
- Palps are also present which are sensory structures

Insects which suck blood have long slender mouthparts for piercing skin
- Hypopharynx
- Mandibles
- Labrum
- Maxillae

Larval mouthparts are prominent
- One pair of hooks
- Cephalo-pharyngeal skeleton
- Mouthparts help identify larvae

Insect Thorax

Divided into three segments
- Prothorax, mesothorax and metathorax

Each segment has one pair of legs attached

One or two pairs of wings may be present on the mesothorax and metathorax

Leg

Leg is attached to the body by coxa

Trochanter

Femur

Tibia

Tarsus, which is composed of several segments

Claw

Wing

Insects usually posess two pairs of wings

Diptera have a reduced second pair of wings called halteres for balance

Membranous outgrowth of the integument

Strengthened by a network of veins comprising breathing tubes (trachea) and blood vessels

The wing venation can be used for identification

Insect Abdomen

Segmented

Soft

Appendages present
- Copulatory claspers
- Ovipositor
- External genitalia

Respiratory System

Branching trachea strengthened by spial thickenings in the walls

Trachea communicate with outside via spiracles
- Spiracles on side of body
- Chitinous openings
- Muscular control so can open and close at will
- Mounted on stigmatic plates

Muscular contactions of the body wall produce repiratory movements

Shape of spiracles and stigmatic plates used for species identification

Alimentary and Excretary System

Alimentary canal divided into fore, mid and hind gut

Foregut:
- Oesophagus
- Crop for temporary food storage
- Proventriculus
- Gizzard present in insects which eat solid food
- Muscular wall and teeth on inner surface

Midgut:
- Stores food
- Secretes enzymes for digestion
- Outlet for malpighian tubules (equivalent of the mammalian kidney)

Hindgut:
- Water resorption

Nervous System

Fat Body

Reproductive System

Life cycles

Fleas

Lice

Nuisance flies

Biting Flies

Myiasis Flies

Oestrus ovis causes infection in nasal cavity
Hypoderma bovis in myositis
Cause skin infections, Simuliidae and Ceratopogonidae transmit onchocerciasis, flies involved in cutaneous habronemiasis and stephanofilariasis, protozoal skin infections
Flea bite hypersensitivity
Culicoides hypersensitivity

@@ Line 1: / Line 1: @@
-#REDIRECT[[:Category:Insecta]]
+{{unfinished}}
+{{toplink
+|backcolour =
+|linkpage =Parasites
+|linktext =PARASITES
+|pagetype=Bugs
+|sublink1=Arthropods
+|subtext1=ARTHROPODS
+}}
+<br>
+==Classification==
+[[Image:Arthropod classifiation.jpg|thumb|right|150px|Arthropod Classification - copyright nabrown RVC]]
+The phylum arthropoda is divided into several subphylums including Chelicerata (which includes the arachnids), Myriapoda, Hexapoda (which includes the insecta), Crustacea and Trilobitomorpha. These are then divided into many classes. The two of major veterinary importance are the '''insecta''' and '''arachnida''' classes.
+==Structure and Function==
+===Insect Body===
+*Covered by an exoskeleton secreted by underlying epidermis
+*Divided into head, body and abdomen
+===Insect Head===
+*Capsule of fused plates at the anterior end of the body
+*One large pair of compound eyes
+**Honeycomb like corneal facets
+*Three simple ocelli
+**Dorsal to compound eyes
+*One pair of antennae
+====Antennae====
+*Form varies amongst insecta
+**E.g. long and segmented, short and squat etc.
+*Hairs sometimes present
+*Aristae (bristles) sometimes present
+====Mouthparts====
+*Modification depending on feeding method
+*Insects which suck up liquified food have an expanded sponge like labellae
+**Cannot penetrate skin
+**Palps are also present which are sensory structures
+*Insects which suck blood have long slender mouthparts for piercing skin
+**Hypopharynx
+**Mandibles
+**Labrum
+**Maxillae
+*Larval mouthparts are prominent
+**One pair of hooks
+**Cephalo-pharyngeal skeleton
+**Mouthparts help identify larvae
+===Insect Thorax===
+*Divided into three segments
+**Prothorax, mesothorax and metathorax
+*Each segment has one pair of legs attached
+*One or two pairs of wings may be present on the mesothorax and metathorax
+====Leg====
+*Leg is attached to the body by '''coxa'''
+*Trochanter
+*Femur
+*Tibia
+*Tarsus, which is composed of several segments
+*Claw
+====Wing====
+*Insects usually posess two pairs of wings
+*Diptera have a reduced second pair of wings called halteres for balance
+*Membranous outgrowth of the integument
+*Strengthened by a network of veins comprising breathing tubes (trachea) and blood vessels
+*The wing venation can be used for identification
+===Insect Abdomen===
+*Segmented
+*Soft
+*Appendages present
+**Copulatory claspers
+**Ovipositor
+**External genitalia
+====Respiratory System====
+*Branching trachea strengthened by spial thickenings in the walls
+*Trachea communicate with outside via spiracles
+**Spiracles on side of body
+**Chitinous openings
+**Muscular control so can open and close at will
+**Mounted on stigmatic plates
+*Muscular contactions of the body wall produce repiratory movements
+*Shape of spiracles and stigmatic plates used for species identification
+====Alimentary and Excretary System====
+*Alimentary canal divided into fore, mid and hind gut
+*Foregut:
+**Oesophagus
+**Crop for temporary food storage
+**Proventriculus
+**Gizzard present in insects which eat solid food
+**Muscular wall and teeth on inner surface
+*Midgut:
+**Stores food
+**Secretes enzymes for digestion
+**Outlet for malpighian tubules (equivalent of the mammalian kidney)
+*Hindgut:
+**Water resorption
+====Nervous System====
+====Fat Body====
+====Reproductive System====
+==Life cycles==
+Fleas
+Lice
+Nuisance flies
+Biting Flies
+Myiasis Flies
+*''Oestrus ovis'' causes infection in [[Respiratory Parasitic Infections - Pathology#Oestrus ovis|nasal cavity]]
+*''Hypoderma bovis'' in [[Muscles Inflammatory - Pathology#Arthropods|myositis]]
+*Cause [[Parasitic skin infections - Pathology#Flies|skin infections]], Simuliidae and Ceratopogonidae transmit [[Parasitic skin infections - Pathology#Onchocerciasis|onchocerciasis]], flies involved in [[Parasitic skin infections - Pathology#Cutaneous habronemiasis|cutaneous habronemiasis]] and [[Parasitic skin infections - Pathology#Stephanofilariasis|stephanofilariasis]], [[Parasitic skin infections - Pathology#Protozoa|protozoal skin infections]]
+*[[Skin Immunologic - Pathology#Flea bite hypersensitivity|Flea bite hypersensitivity]]
+*[[Skin Immunologic - Pathology#Culicoides hypersensitivity|Culicoides hypersensitivity]]