prof. dr. badr el- sabah entomology lecture 2

Lecture 2

Phylum Arthropoda Class: Insecta

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Abdominal Appendages(Head- Thorax- Abdomen)

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•Compound Eyes (C) -made up of many small lenses, called ommatidia.

•Purpose: detect movement, light intensity and color.

•Simple Eyes (S) -“ocelli” Insects have 0-3 simple eyes. Purpose: detect light intensity.

Head appendages – 1-Eyes

C

C

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IIIIInsect Head – 2- Antennae

• Insects have one pair of antennae.• May have the function of touch, smell, and in

some cases, hearing.• Used for navigation, food location, grasping (in

some species)• Used for detection of:

• temperature• chemicals produced by plants or other foods• chemicals produced by other members of their

species (pheromones)

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Insect Head – 2-Antennae• Shape, number, and size of the segments are frequently used for

identification.• The overall appearance of the antennae are also used in identification.

plumoselamellate serrate filiform

geniculate

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antennae

The antennae are a pair of sense organs located nearthe front of an insect's head capsule. Althoughcommonly called "feelers", the antennae are muchmore than just tactile receptors. They are usuallycovered with olfactory receptors that can detectodor molecules in the air (the sense of smell). Manyinsects also use their antennae as humidity sensors,to detect changes in the concentration of watervapor. Mosquitoes detect sounds with theirantennae, and many flies use theirs to gauge airspeed while they are in flight.

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Antennal Segments

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Types of Antennae

a. and f. Filiform –thread-like h. Geniculate –elbowed

b. Moniliform –bead-like i. Lamellate –plate-like

c. Setaceous –hair-like g. Capitate – head-like (less enlarged at the tip would be clavate –clublike

d. Serrate –sawtoothed j. Plumose –plumed or feather-like

e. Pectinate –comb-like 9Prof. Dr. Badr El-Sabah / Lecture2

Setaceous --bristle-like

Dragon fly10

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Filiform -- thread-like

Ground beetle11

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Serrate -- sawtoothed

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Moniliform -- bead-like

Termite13Prof. Dr. Badr El-Sabah / Lecture2

Clavate --gradually clubbed

Carrion beetle 14

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Capitate -- abruptly clubbed

Butterfly 15

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Lamellate -- nested plates

Scarab / Rhinoceros beetle16

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Pectinate -- comb-like

Fire-colored beetle 17

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Plumose -- brush-like

Mosquito18

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Geniculate -- elbowed

Ant 19Prof. Dr. Badr El-Sabah / Lecture2

Aristate -- pouch-like with lateral bristle

House fly20Prof. Dr. Badr El-Sabah / Lecture2

Types of Mouth Parts

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Orientation of Mouthparts

• Prognathous –projecting forward (horizontal)

• Hypognathous – projecting downward

• Opisthognathous –projecting obliquely or posteriorly

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1. CHEWING MOUTH PARTS - Animals w/ these are

likely to feed upon plant material such as leaves Ex.

Grasshopper & Locust

2. PIERCING & SUCKING MOUTH PARTS:

- These animals will feed on different food sources Ex.

Mosquito sucks blood from its host

piercing/suckingchewing

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Generalized insect MOUTHPARTS

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There are five different structures which are used for

the initial collection and processing of food:- Labrum -

a cover which may be loosely referred to as the upper

lip. Mandibles - hard, powerful cutting jaws. Maxillae -

'pincers' which are less powerful than the

mandibles. They are used to steady and manipulate

the food. They have a five segmented palp which is

sensory and often concerned with taste. Labium - the

lower cover, often referred to as the lower lip. It

actually represents the fused pair of ancestral second

maxillae. They have a three segmented palp which is

also sensory. Hypopharynx - a tongue-like structure in

the floor of the mouth. The salivary glands dischargesaliva through it. Biting Mouthparts.

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From Gullen & Cranston 2000

The mouthparts of most

insects are highly

specialized for a single

purpose.

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The paired mandibles and maxillae are formed into

needle-like structures (stylets) which are enclosed by

the labium. When a mosquito 'bites', the

pointed and barbed pair of maxillae penetrate the

dermal tissue of the vertebrate to anchor the

mouthparts in the tissue. This also provides leverage

when the other mouthparts are inserted. The sheath-

like labium slides back and the remaining mouthparts

pass through its tip and into the tissue. The mosquito

injects saliva, which contains anticoagulants, into the

tissue to stop the blood from clotting. The labrum acts

like a tongue and is used to suck up the blood.

Piercing & Sucking Mouthparts.

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3. LAPPING MOUTH PARTS:

- An example of an insect wh/ has these is the housefly as it

feeds on various food sources

4. SIPHONING MOUTH PARTS:

- The insect will have a very long coiled structure called the

PROBOSCIS

- The PROBOSCIS is used for feeding on the nectar found

in flowers

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Adult housefly mouthparts.

from Gullen & Cranston 2000

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Mouthparts are soft and end in spongy pads.

Houseflies depend on their keen sense of smell,

provided by their antennae. For tasting andconsuming meals, the insect uses its proboscis, a

plunger-like appendage that extends from the bottom

of the head. Two small, antenna-like feelerscalled maxillary palps allow the fly to taste its food The

end portion of the proboscis, called the labellum,

terminates in a spongy mouth, where the fly slurps its

food. It feeds only on liquids. It regurgitates part of its

last meal on to its next meal. This liquid and the

enzymes in it soften and liquefy part of the solid which

the fly then mops up. This is another way of spreading

germs. Also it frequently defecates while feeding.Sponging & Sucking Mouthparts.

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from Gullen & Cranston 2000

Specialized mouthparts of butterfly.

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Found in butterflies and some moths (Lepidoptera). The

probiscis (galea) is a modification of the maxillary galea

found in the more primitive madibulate (chewing)

mouthparts, as seen in the cockroach. The probiscis

consists of paired galea which, during feeding, fit

together to form a tube that is used to suck up nectar (it

acts like a straw). When not in use the proboscis is

coiled and held close to the underside of the head.The

Morgan's sphinx moth, Xanthopan morgani , has

the longest proboscis at 30 to 35 cm in length. SiphoningMouthparts

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5- Cewing Lapping . Multi-purpose mouthparts of the honey

bee, a facilitation & consequence of social life.

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This is accomplished by having both mandibles and a

proboscis. The mandibles are the paired "teeth" that

can be open and closed to chew wood, manipulate

wax, cleaning other bees, and biting other workers or

pests (mites). The proboscis is mainly used for

sucking in liquids such as nectar, water and honey

inside the hive, for exchanging food with other bees

(trophallaxis), and also for removing water from

nectar. The workers can put a droplet of nectar

between the proboscis and the rest of the mouth parts

to increase the surface area, and slowly moving the

proboscis back and forth. Chewing & SuckingMouthparts

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THANKS

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