Also contains materials about fat bodies, exocrine and endocrine glands and pheromones of insects.

1. Presented By: Muzna Kashaf(030)
Tehreem Afzal(044)
Faiza Batool (035)
Sense organs and nutritive requirements of
insects

2. Contents
• Sense organs
– Mechanoreceptors
– Chemoreceptors
– Photoreceptors
• Sound producing organs
• Light producing organs
• Nutritive requirements
• Fat body
• Exocrine and endocrine glands
• Pheromones
– Alarm pheromones
– Trail pheromones
– Aggregation pheromones
– Sex pheromones

3. Sense organs
• Receive stimuli.
• Transfer to neuromuscular system.
• Variety of behaviour is seen.
Mechano-
receptors
Chemo-
receptors
Photo-
receptors

4. Mechanoreceptors
× Respond to the sense of touch due to contact with
external objects.
4
The Trichoid Sensilla
The Companiform Sensilla
• a. Johnstons organ
• b. Auditory or tympanal organ
The Chordotonal Organ

5. Types Of Mechanoreceptors
5
(A) Trichoid sensillum (B) Campaniform organ (C) Chordotonal organ
.

6. Chemoreceptors
× Chemoreceptor is sensitive to chemicals.
× It has following two types:
6
Olfactory
chemorecptors
Gustatory
Chemoreceptors

7. Photoreceptors
× Able to perceive light.
× Photoreceptors in insects are:
7
Compound
eyes
Dorsal
ocelli
Lateral
ocelli

8. PHOTORECEPTORS
Fig. : Compound eye (Ommatidium)

9. Sound Producing Organs
× Sound-producing structures involve any part of the insect's
exoskeleton.
× It is located differently in different groups.
Mechanism:
× Mechanism, for the producton of sound are ;
 Vibration and Tremulation
 Percussion
 Stridulation
 Click Mechanism
 Air Expulsion

10. Vibration: Osscilation
of abdomen.
Tremulation: Sound
production transmitted
through the legs to the
substrate.
Percussion: Striking of
body part with the tip of
the abdomen.
Stridulation: Sounds
produced by frictional
mechanisms in a regular
patterned manner
Click mechanism:
Unusual exhalatory
sounds, often expelled
via the tracheal spiracles.

11. Functions
× Mate finding
× Species-specific recognition
× Mating inducement
× Queen stimulation
× Colony alarm
× Defensive and territorial behaviour

12. Light Producing Organs
× Associated with production of light.
× Present on different positions in different groups.
× Different colours of light is produced.
Example:
× Hemiptera produces white light.
× Diptera produces blue-green light.

13. Light Producing Organs

14. Mechanism
• Light is produced in organelle called peroxisome.
• Followig here is the mechanism.
• Luciferin
Adenylation in
presence of luciferase
and Mg-ATP
• luciferyl
adenylate
Oxygenation in
presence of molecular
oxygen
• Oxyluciferin
Emission of Light

15. Nutritive Requirements
 Nutrients are essential for meeting energetic needs
associated with;
 They get their nutrients from a wide range of different
food sources.
General
maintenance
Fueling
growth
Reproduction

16.  Example:
• Beetles wood.
• Cockroaches and crickets detritus.
• Sucking lice and some flies vertebrate blood.
• Insects having sucking mouthparts
plant phloem (aphids)
plant xylem (spittlebugs
and cicadas)

17. CONTINUED.....
Nutrients required:
Carbohydrates Amino acids
Vitamins (A ,C,
D, E and B
complex)
Cholestrol Water
Minerals (P, K,
Fe, Ca, Zn, Cu,
Co)

18. Fat Body
• It is a dynamic tissue involved in multiple metabolic
functions.
Functions:
Metabolism of carbohydrates,
lipids and nitrogenous
compounds
Storage of glycogen, fat and
protein
Regulation of blood sugar
Protein synthesis:
hemolymph proteins
lipophorins
vitellogenins
Functions of fat
body

19. Fig. Fat body

20. Exocrine and Endocrine glands
in insects
Exocrine glands :
• Secrete products into ducts.
• Ducts lead into the lumens of various organs.
• Ectodermal in origin
• Widely scattered over the insect.

21. Example
• Simple unicellular gland
• Unicellular cell with ductile cell
• Simple aggregations of gland cells
• Aggregation of gland cells with common duct
• Complex aggregation of glands with common duct

22. Fig. Exocrine glands

24. Functions
• Venoms
• Alarm pheremones
Defense
• Chemical signals (pheromones)
Intraspecific communication
• Wax and silk
• Epidermal glands secrete wax in honeybees.
Building structural material
• Salivary glands
• Accessory gland and spermathecal gland assist transport
of spermatozoa
Transport of material in liquid state

25. Endocrine glands
• Ductless glands.
• Secretions(Hormones) are released directly into the
Hemolymph.
• In insects the largest endocrine glands are found in the
Prothorax.
• Major endocrine structures :
Corpora allata
Corpora
cardiaca
Thoracic
glands

27. Function Of the Endocrine
glands
Regulation of
molting
Determination of
form at
metamorphosis
Polymorphism
Regulation of
diapause
Involvement in
reproduction
Regulation of
metabolic activities
and general body
functions
Regulation of
preprogrammed cell
death
Regulation of
behaviour

28. Pheromones
• Chemicals released by an organism.
• Cause a specific reaction in a receiving organism of the
same species.
• They are;
 Effective
 Volatile in nature
 Serving as chemical means of communication

29. Classification
Primer effect
Releaser effect
Sex
pheromones
Aggregation
pheromones
Trail
pheromones
Aalarm
pheromones

30. Sex Pheromone

31. Aggregation Pheromones
 Produced by one or both sexes.
 Bringing both sexes together for feeding and
reproduction.
 Known mostly in coleopterons,a pentatomid bug.
Example:
 Frontalin
 Ipsenol
 Periplanone
 Dimethyldecanol etc.

32. Alarm Pheromones
• They are reported in Homoptera, Isoptera, Hymenoptera.
• Produced by a variety of organs such as:
 Pair of cornicles near the tip of the abdomen in aphids.
 Cephalic glands in termites.
 Poison glands in ants.
• Antipredatory device.
• Chemically they are terpenes (aphids), formic acid (ants)
and aldehyde (hemipterans).

33. Trail Pheromones
• Used to find mates, or to utilise food resources more
efficiently.
• Maintains the cohesion and social integration of the
colony.
Example:
• Ant-trails

34. References
•Hoy, R.R., Robert, D. (1996). Tympanal hearing in insects. Annual
review of entomology, 41(1), 433-450.
•Ali. R. Introduction to entomology. Sense organs of insect.
Department of Entomology, Sher-e-Bangla Agricultural
University.Pp1-9.
•Chapman RF, (1998) The insects: structure and function, 4th edn.
Cambridge University Press, Cambridge, 770 pp.
•Simpson SJ, Raubenheimer D (2000) The hungry locust. Adv
Study Behav 29:1–44
•Chapman RF,2013,The insects, Structure and Function, 5th edition.
•Happ, G. M. 1969. "Multiple sex pheromones of the mealworm
beetle, Tenebrio Molitor Linnaeus." Nature, volume 222: 80-181.