6th Module, insects (respiratory, digestive and integument system)and entomology-.pptx

Insects tegument, digestive system, respiratory system of insects.

1. CONTENTS Tentorium Digestive system Respiratory system and types of respiration

2. TENTORIUM

3. Tentorium The body wall in insects becomes inpushed or invaginated to form rigid process called apodemes . The framework of these apodemes is called endoskeleton . The endoskeleton of head is called tentorium. The tentorium is named from its resemblance with a tent which is tightened by four ropes.

4. Tentorium

5. Functions of Tentorium Afford a basis for the attachment of cephalic muscles. Provide rigidity to the head. Support to the brain and fore intestine. Strengthen the points of articulation of certain mouthparts.

6. It consists of four openings: An upper Two lateral A lower one Tentorium

7. Alaforamen Through which pass the alimentary canal . Neuraforamen Through which pass nervous system The tentorium is X-shaped and consists: A central body Two anterior arms Two posterior arms Two dorsal arms

8. Corpotentorium The central body is a large triangular plate called corpotentorium Pretentorium Two anterior arms are broadened at their anterior ends and are the ingrowths from the anterior tentorial pits. Metatentorium Two posterior arms are broader at their posterior ends and are the invaginations from the posterior tentorial pits. Supratentorium Two dorsal arms are the outgrowth from the bases of the anterior arms. They are sclerotised threads slightly broadened at their tips.

9. DIGESTIVE SYSTEM

10. Digestive System Insects feed on a wide range of organic materials. Almost 75% of all species of insects are phytophagous . Insects may be: Carnivorous Entomophagous Wood borers Wool feeders or saprophytic, Parasitic on other animals or insect species.

11. There are structural modifications in the digestive system . If the food ingested in a liquid form, it may be: Plant sap Nectar Blood Sap suckers possess a filter chamber Solid feeders have well developed gizzard.

12. start cutting here stop cutting here Alimentary Canal A long, muscular and an enclosed tube that extends from the mouth to the anus. insert the tip of scissor under the top surface of the abdomen. Cut straight up the middle of the abdomen up to the head.

13. . Alimentary Canal

14. The alimentary canal in insects is divided in to three regions: Foregut (stomodaeum) food is stored, filtered and partially digested. Midgut ( mesenteron or stomach or ventriculus ) primary site for digestion and aborption of food. Hindgut ( proctodaeum ) some abosorption and feces formation occur Alimentary Canal / Digestive gut Foregut Mid gut Hind gut

15. Structure of Alimentary Canal

16. Starts from mouth cavity to gizzard or proventriculus . The mouth cavity: labrum as upper lip, labium as lower lip with mandibles and maxillae laterally and hypopharynx at the centre . At the base of the hypopharynx , salivary glands open into the mouth cavity. Foregut

17. Salivary glands The glands are grape-like clusters called acinus . Involved in the secretion of salivary juices into the salivary ducts. The secretion of the glands contain: amylases, lipases, proteases etc.

18. Foregut is divided into: Pharynx region between the mouth and oesophagus . Oesophagus it is a narrow part, food get transported from pharynx into the crop. Crop It is a sac like structure which is a dilated and store food material. Gizzard It is a small constricted part modified in to a teeth like denticles that grind the food material. The junction of foregut and midgut is provided with a cardiac ( oesophageal ) valve. Structure of Foregut

19. A short, cylindrical and straight tube. Its anterior end arise six large, elongated sacs, the gastric caeca which consists of a longer anterior lobe and shorter posterior lobe. The posterior lobes are filled with food whereas the anterior lobes have secretary function. The posterior end of the mid-gut is marked by the presence of malpighian tubules. At the junction of mid-gut and hindgut is a pyloric valve. Structure of Mid-gut

20. The midgut has a very thin and delicate layer called peritrophic membrane secreted by the epithelial cells. The peritrophic membrane protects the tender epithelial cells / secretary cells of the midgut from friction by hard food particles. It forms a coat over the food particles. Midgut ( Peritorphic membrane)

21. Hindgut is divided into 3 regions; Ileum (small intestine) is a thick and straight tube. Colon (large intestine) is a short narrow tube which dilates posteriorly to merge into the rectum. Rectum: wider tube provided with six bands of longitudinal muscles alternating. These are involved in reabsorption of water and salts from the faecal matter. The rectum ends into an anal opening. Hindgut

22. Digestion take place in following 5 steps: Ingestion Transportation Digestion Absorption Egestion Process of Digestion

23. 1. Ingestion Food is partially digested in the oral cavity with the help of salivary enzymes. 2. Transportation The food material entered in to the oesophagus is transported in to the crop by muscular activity. From the crop, food enters in to the gizzard where it is still broken in to very minute particles with the help of denticles or the cuticular teeth. Digestion take place in 5 steps

24. 3. Digestion From gizzard food passes in to the midgut where actually digestion starts. The epithelial cells produce enzymes i.e. Proteases which break proteins in to aminoacids , Carbohydrases breaking carbohydrates in to mono & disaccharides, Lipases breaking lipids in to fatty acids and glycerol.

25. 4. Absorption Midgut epithelial cells absorb the nutrients from the digested food and pass on the faecal matter and undigested food material in to the hindgut. 5. Egestion: The waste food material is discharged through the anus due to the action of the anal muscles.

26. RESPIRATORY SYSTEM

27. Respiratory system In insects, exchange of gases takes place through tubular structures, called trachea. They are distributed throughout the body collectively forming tracheal system. These trachea open outside on the body wall through small openings called spiracles. The tracheal system with functional spiracles is called the open tracheal system and with non-functional spiracles is called closed tracheal system .

28. Spiracles The spiracles are the external openings through which air enters and leaves the body. They consists of a small ring like sclerite at opening called ‘ peritreme ’ leading to a cavity known as atrium’.

29. Ak -grasshopper has 10 pairs of spiracles: 2- thoracic (one between the prothorax and mesothorax and the other between the meso and metathorax ). 8- abdominal (one on each side of the first eight abdominal segmens ). Spiracles in grasshopper

30. Trachea Trachea are fine elastic tubular structures. The cuticular lining appear as a spiral thickening throughout the length of trachea tube. Spiral thickenings are known as ‘ taenidia ’ which support to the trachea from being collapsed when no air.

31. Tracheoles The trachea divide into very fine branches known as tracheoles which are about 0.1-1 µm in diameter. Tracheoles form a network over the visceral organs including the alimentary canal as well as the gonads (ovaries, tests) and penetrate into the tissues of organs and supply oxygen to the tissues.

32. Tracheal trunks The trachea coming from spiracles through out the body join with those of neighbouring spiracles forming ‘longitudinal trunks’ . Dorsal trunk Supply oxygen to proximal part of body and heart Lateral trunks Spread tracheoles to alimentary canal, legs, wings. Ventral trunk Supply oxygen to the central nervous system.

33. Tracheal trunks (Video Resp. B)

34. Types of respiration

35. Respiration in Terrestrial Insects e.g. Grasshopper, Crickets etc.

36. Extraction of Oxygen by gills Spiracles are closed and non-functional. Molecular oxygen in water extracted by thin-walled gills. Tracheal gills These are outgrowth of trachea which are thread like and richly supplied with trachea and tracheoles . Presesnt on the sides or end of abdomen. e.g. nymph of mayflies, stonefly, dragonfly, damselfly Spiracular gills Spiracles are closed and non-functional. These are outgrowth of spiracles that directly open into the trachea. Blood gills Filled with blood and finger like. e.g. some larvae of true flies Respiration in aquatic Insects

37. Extraction of Oxygen by gills Mayfly nymph Stonefly nymph

38. Damselfly and Dragonfly

39. Diffusion of oxygen through body wall It is also called cutaneous respiration. Tracheal system closed. e.g. 1 st instar larvae of Chironomus ( Diptera )

40. Utilization of oxygen of aquatic plants Some insects with open tracheal system get oxygen from submerged vegetation. Capture air bubbles from the surface of plants with hydrofuge hairs on different parts of the body. These insects live in the bottom mud and have spiracles at the tip of abdomen. e.g. coleoptera , Diptera

41. Utilization of atmospheric oxygen Spiracles are open Maintain a semi-permanent connection with the air through a long respiratory tube (Siphon). Exchange of gases in tracheal system occur through frequent visits to surface of water. Hover fly Water scorpion Mosquito larave Diving beetle Aquatic bugs Aquatic beetles

42. i. Hover fly Spiracle on the tip of a long telescopic siphon at the end of abdomen. At respiration siphon extended, breaking water surfaces, reaches water surface to get oxygen. When siphon retract peristgmatic glands prevent water entry into spiracle.

43. Water scorpion & Mosquito larvae Respiratory tubes present at the end of abdomen carry spiracles at their bases. Spiracles are surrounded with: Dense group of hydrofuge hairs (water scorpion) Provided with valves (Mosquito larvae)

44. Diving beetle Take air- bubbles beneath their elytra when visit water surface

45. Plastron respiration The plastron is a special type of air store in the form of a thin film held by a system of hydrofuge hairs or scales. If there is adequate oxygen dissolved in water, the plastron can act as a permanent physical gill. e.g. aquatic bugs and beetles

46. Respiration in endoparasitic insects Like aquatic insects they extract oxygen from the blood of host or make contact with atmosphere. Cutaneous respiration e.g. Brachonid , Ichneumonid Through caudal filaments e.g. Brachonid parasite Atmospheric oxygen e.g Chalcid larvae

47. Respiration in endoparasitic insects Brachonid wasp Ichneumonid Chalcid

48. THANKS