Lecture 2 - The Insect Head and Mouthparts Flashcards
Basic Components of an Insect (3)
Head
Thorax
Abdomen
Head
Consisting of the brain, mouthparts that is used for ingesting food, major sensory organs (antenna / compound eyes)
Thorax
Consisting of legs and wings
Abdomen
Consisting of the major organs
Compound eyes
(2)
These are located on the head of the insect used to detect motion
Adjacent to the compound eyes are 3 ocelli used to detect vision / light perception
Antenna
These are located on the head of the insect used to detect food and pheromones released by the females
If the maxillary palps and labium palps are absent therefore
this would destroy the insect ability to taste food
Segmentation of the thorax (leg)
(3) + Description
The thorax is divided into 3 components
a. Anterior thorax (Prothorax)
b. Middle Thorax (Mesothorax)
c. Posterior Thorax (Metathorax)
Where are the legs attached to on the insect?
The 3 pairs of legs are attached to the prothorax, mesothorax, and metathorax
Segmentation of the thorax (Wings)
(2) + Description
There are two pairs of wings known as the forewings and the hind wings
a. The forewings are attached to the mesothorax
b. Hindwings are attached to the metathorax
Insect Exoskeleton
(2)
The insect exoskeleton is known as the sclerites (these are divided into plates that are chemically harden to form the integument through a process known as sclerotization)
The sclerites would molt to shed its cuticle
The function of the exoskeleton (sclerites)
(2)
Serves as a barrier for water (to prevent the insect from desiccating - drying out)
Serves as a component for muscle attachment as it consists of sensory component for the environment
Structure of the Exoskeleton (Sclerites)
(3)
a. Suture
b. Sulcus
c. Apodeme
Suture
These are lines or grooves that forms the union of the two scleritis
Sulcus
The line that arises from the invagination of the cuticle
Apodeme
Provides muscle attachment site for the internal organs
Segmentation
(2)
- Segmentation in insects are visible everywhere on the insect body EXCEPT the head
- There is no segmentation on the head of the insect b/c the segment of the head has become fused as a continuous component creating a head capsule
6 segments on the head including their appendages
Labral - Labrum
Antennal - Antenna
Postantennal (intercalary)
Mandibular - Mandibles
Maxillary - Maxilla
Labial (bears a labium)
Jaws of the insect
(2)
The mandible acts as the first pair of jaw
Maxillary acts as the second pair of jaw that helps hold the food
Major region of the insect
(5) + Description
Frons - Front (Face)
Clypeus - a plate located beneath of the frons
Vertex - (Top of the head)
Occiput - (back of the head)
Gena - Side of the head below the compound eye (“cheek”)
Types of Mouthparts (5)
a. Labrum
b. Mandibles
c. Hypopharynx
d. Maxilla
e. Labium
Labrum
(Upper lip), this is a flap that is hanging over the mouth part to cover it
Mandibles
(Teeth), that moves from side to side, used for chewing and cutting the food
Hypopharynx
Tongue
Maxilla
Guide food, acts as sensory palp
Labium
Lower lip that acts a sensory palp
Mouthparts: Chewing
(Eg. Orthoptera/ Dictyoptera / Coleoptera )
Piercing and Sucking
(Eg. Hemiptera and Diptera)
Sponging
Diptera
Rasping and Sucking
(Thysanoptera - Thrips
Mouthparts of House Fly (3)
Sponging mouth parts
Consisting of labium which is arranged in a proboscis (tube) used to suck up the liquid food
The mandibles are absent and the maxillae are unjointed
Mouthpart of the Mosquito
(2)
Piercing and Sucking
They consists of 6 mouthparts that make up 6 stylets
6 mouthparts that make up 6 stylets
1 Labrum
2 mandibles
2 maxillae (Note: The mandibles and maxillae are long, needle shaped that pierces the skin)
1 hypopharynx
What happens to the 6 stylets that are not used in the mosquitoes?
When the 6 stylets are not used the labium forms a sheath that encloses them
The salvia of the mosquito consists of
(3)
Anesthetic
Anticoagulant
Vasodilato
Mouthpart of the Horsefly
Piercing and Sucking
Components of Piercing and Sucking in Horsefly
(3) + Description
2 mandibles (curved, sword like, that slashes the skin)
2 maxillae (sharp, pointed that drills the skin)
Labium (sponges the blood)
Mouthpart of Hemiptera
Piercing and Sucking
Component of Piercing and Sucking in Hemiptera
(3) + Description
2 mandibles
2 maxillae (Note: the mandibles and maxillae are sharp and pointed that forms the proboscis)
Labium forms a sheath
Mouthpart of Butterflies and Moth
Siphoning
Component of Siphoning in Butterflies and Moth
(4) + Description
Maxillae (forms the proboscis which is a sucking tube)
The mandibles and hypopharynx is absent
The labium is reduced
The maxillary palps and labial palps are reduced
Mouthparts of Bees and Wasp
Chewing and Lapping
Component of Chewing and Lapping in Bees and Wasp
(3)
Maxillae and labium forms the proboscis where the saliva is discharged and nectar is drawn up
The mandibles is present to clean the cells, move stuff, defense, mold wax, NOT used for feeding
However the mandible is used for chewing in wasps
In some immature (larval) insects, the only part of the body that is sclerotized is the head capsule. Why?
B/c insects need to chew the food, if the food is not hardens that mean that head will collapse
Orientation of the Mouthparts
(3)
a. Hypognathous (downward)
b. Prognathous (forward)
c. Opisthognathous (rearward / backward)
Hypognathous (downward)
Eg: Orthoptera
Prognathous (forward)
Eg. Coleoptera
Opisthognathous (rearward)
Eg. Hemiptera
