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Agriculture

1. ANM 311 – NEMATODE PESTS OF HORTICULTURAL CROPS AND THEIR MANAGEMENT ( 1+1 ). K.ANUSHIYA 2021022007

2. EXCRETORY SYSTEM OF NEMATODES The excretory system is not well developed in nematodes . The excretory pore is located in the anterior midventral line close to the Nerve Ring. The position of excretory pore may vary in different genera and even in different stages of the same species. In T.semipenetrns the excretory pore is located in the posterior region and it’s function is rather secretory than excretory. It secrets gelatinous matrix. The excretory system of nematodes are of two types. Glandular type Tubular type.

3. GLANDULAR TYPE The glandular type consists of a single specialised cell known as Renette Cell. It had a posterioly located enlarged gland known as Excretory gland or ventral gland. This gland is connected to the excretory pore by a duct that terminates in a pouch like structure known as ampulla. This type is found in members of the class Adenophorea .

4. GLANDULAR TYPE

5. TUBULAR TYPE The tubular type of excretory system consists of four – cuticularised canals. Two are anterior and another two are posterior canals. There is a pouch like structure in the middle which connects both the lateral canals. It is known as excretory pore. There are four types in tubular system. Asymmetrical or Tylenchid type Inverted ‘ U ‘ shaped or Ascarid type Rhabditid type Simple ‘ H ’ shaped type.

6. TUBULAR TYPE

7. FUNCTIONS OF EXCRETORY SYSTEM Excretion of toxic substances . Secretion of certain chemicals. Osmoregulation. In T . Semipenetrans , excretory pore secretes gelatinous matrix which bind and protect the eggs from abnormal environmental conditions.

8. NERVOUS SYSTEM OF NEMATODES

9. NERVOUS SYSTEM OF NEMATODES In plants parasitic nematodes ,the nervous system is not well developed. Though they possess very primitive type of nervous system,they also respond to different stimuli. The nervous system in plant parasitic nematodes is of two types. They are , Peripheral Nervous System Central Nervous System

10. PERIPHERAL NERVOUS SYSTEM In plant parasitic nematodes,it is located in the periphery which mainly includes body cuticle and also the cephalic and caudal regions. The parts of nervous system located are well connected with the Nerve Ring. which encircles the isthumus region of oesophagus and are considered to be the most important part of the nervous system . The peripheral nervous system includes the sensory organs such as Cephalic papillae, Amphids , Cephalids , Hemizonid Hemizonions , Deirids .

11. CENTRAL NERVOUS SYSTEM Central Nervous System comprises the Nerve Ring which is band of nerve fibres. It encircles isthumus . Nerve ring governs various functions of the nematode body. A few species of nematodes are known to have two nerve rings. Associated with this nerve ring and supply the lips and associated sense organs . The ventral Nerve which runs in the ventral chord is the largest ganglion runs posteriorly along each lateral chord and in many nematodes sub-dorsal and sub-ventral nerves are also present. The dorsal and lateral nerves have a few ganglion associated with them but the ventral nerve has several ganglion along its length.

12. TRANSMISSION ALONG NERVES Nothing is known about the processes involved in the conduction of an impulse along nerves in nematodes. In Ascarid , it is known that the pseudocoelomic fluid contains more sodium as compared with potassium ions . It is thus possible to speculate that the Nerve axons in this species function as that of other animals in which the action current arises from an influx of external sodium ions. Acetylcholine is apparently involved in nervous transmission in nematodes. Acetylcholine like substances have been detected in Ascaris .

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