Lecture 2 - The Insect Head and Mouthparts

Question 1

Basic Components of an Insect (3)

Answer 1

Head

Thorax

Abdomen

Question 2

Head

Answer 2

Consisting of the brain, mouthparts that is used for ingesting food, major sensory organs (antenna / compound eyes)

Question 3

Thorax

Answer 3

Consisting of legs and wings

Question 4

Abdomen

Answer 4

Consisting of the major organs

Question 5

Compound eyes

(2)

Answer 5

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

Question 6

Antenna

Answer 6

These are located on the head of the insect used to detect food and pheromones released by the females

Question 7

If the maxillary palps and labium palps are absent therefore

Answer 7

this would destroy the insect ability to taste food

Question 8

Segmentation of the thorax (leg)

(3) + Description

Answer 8

The thorax is divided into 3 components

a. Anterior thorax (Prothorax)

b. Middle Thorax (Mesothorax)

c. Posterior Thorax (Metathorax)

Question 9

Where are the legs attached to on the insect?

Answer 9

The 3 pairs of legs are attached to the prothorax, mesothorax, and metathorax

Question 10

Segmentation of the thorax (Wings)

(2) + Description

Answer 10

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

Question 11

Insect Exoskeleton

(2)

Answer 11

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

Question 12

The function of the exoskeleton (sclerites)

(2)

Answer 12

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

Question 13

Structure of the Exoskeleton (Sclerites)

(3)

Answer 13

a. Suture

b. Sulcus

c. Apodeme

Question 14

Suture

Answer 14

These are lines or grooves that forms the union of the two scleritis

Question 15

Sulcus

Answer 15

The line that arises from the invagination of the cuticle

Question 16

Apodeme

Answer 16

Provides muscle attachment site for the internal organs

Question 17

Segmentation

(2)

Answer 17

• 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

Question 18

6 segments on the head including their appendages

Answer 18

Labral - Labrum

Antennal - Antenna

Postantennal (intercalary)

Mandibular - Mandibles

Maxillary - Maxilla

Labial (bears a labium)

Question 19

Jaws of the insect

(2)

Answer 19

The mandible acts as the first pair of jaw

Maxillary acts as the second pair of jaw that helps hold the food

Question 20

Major region of the insect

(5) + Description

Answer 20

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”)

Question 21

Types of Mouthparts (5)

Answer 21

a. Labrum

b. Mandibles

c. Hypopharynx

d. Maxilla

e. Labium

Question 22

Labrum

Answer 22

(Upper lip), this is a flap that is hanging over the mouth part to cover it

Question 23

Mandibles

Answer 23

(Teeth), that moves from side to side, used for chewing and cutting the food

Question 24

Hypopharynx

Answer 24

Tongue

Question 25

Maxilla

Answer 25

Guide food, acts as sensory palp

Question 26

Labium

Answer 26

Lower lip that acts a sensory palp

Question 27

Mouthparts: Chewing

Answer 27

(Eg. Orthoptera/ Dictyoptera / Coleoptera )

Question 28

Piercing and Sucking

Answer 28

(Eg. Hemiptera and Diptera)

Question 29

Sponging

Answer 29

Diptera

Question 30

Rasping and Sucking

Answer 30

(Thysanoptera - Thrips

Question 31

Mouthparts of House Fly (3)

Answer 31

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

Question 32

Mouthpart of the Mosquito (2)

Answer 32

Piercing and Sucking They consists of 6 mouthparts that make up 6 stylets

Question 33

6 mouthparts that make up 6 stylets

Answer 33

1 Labrum 2 mandibles 2 maxillae (Note: The mandibles and maxillae are long, needle shaped that pierces the skin) 1 hypopharynx

Question 34

What happens to the 6 stylets that are not used in the mosquitoes?

Answer 34

When the 6 stylets are not used the labium forms a sheath that encloses them

Question 35

The salvia of the mosquito consists of (3)

Answer 35

Anesthetic Anticoagulant Vasodilato

Question 36

Mouthpart of the Horsefly

Answer 36

Piercing and Sucking

Question 37

Components of Piercing and Sucking in Horsefly (3) + Description

Answer 37

2 mandibles (curved, sword like, that slashes the skin) 2 maxillae (sharp, pointed that drills the skin) Labium (sponges the blood)

Question 38

Mouthpart of Hemiptera

Answer 38

Piercing and Sucking

Question 39

Component of Piercing and Sucking in Hemiptera (3) + Description

Answer 39

2 mandibles 2 maxillae (Note: the mandibles and maxillae are sharp and pointed that forms the proboscis) Labium forms a sheath

Question 40

Mouthpart of Butterflies and Moth

Answer 40

Siphoning

Question 41

Component of Siphoning in Butterflies and Moth (4) + Description

Answer 41

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

Question 42

Mouthparts of Bees and Wasp

Answer 42

Chewing and Lapping

Question 43

Component of Chewing and Lapping in Bees and Wasp (3)

Answer 43

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

Question 44

In some immature (larval) insects, the only part of the body that is sclerotized is the head capsule. Why?

Answer 44

B/c insects need to chew the food, if the food is not hardens that mean that head will collapse

Question 45

Orientation of the Mouthparts (3)

Answer 45

a. Hypognathous (downward) b. Prognathous (forward) c. Opisthognathous (rearward / backward)

Question 46

Hypognathous (downward)

Answer 46

Eg: Orthoptera

Question 47

Prognathous (forward)

Answer 47

Eg. Coleoptera

Question 48

Opisthognathous (rearward)

Answer 48

Eg. Hemiptera