Nematode Pests of Horticultural Crops and their Management (1+1)

Reproductive System

REPRODUCTIVE SYSTEM

• Nematodes are dioecious i.e. males and females are separate.
• In general appearance, both the sexes look alike except in the region of tail which is more arcuate in male nematodes due to presence of copulatory structures called spicules and usually bursa.
• Reproductive system is tubular and is often referred as genital tract.
• Reproductive system remains suspended in the pseudocoelom/body cavity.
  

Female Reproductive System

• The various parts of the female genital tract are ovary (gonad), oviduct, spermatheca, uterus, vagina and vulva.
• The oocytes are formed in the apical zone of ovary from where they move down and grow in size in the growth zone.
• On maturation, they pass down to spermatheca via oviduct. Spermatheca, if present stores the sperms after mating and when the oocytes pass through it, they get fertilized.
• Further layers on the egg (ovum) are laid while it is passing through the glandular crusta formeria of the uterus.
• Vagina helps in the expulsion of egg to the outside and opens on the ventral side through a slit-like opening, the vulva.
• Females may possess only one gonoduct (monodelphic) which may be directed anteriorly (prodelphic) or posteriorly (opisthodelphic).
• In those females which possess 2 gonoduct (didelphic), the uteri of two gonoducts unite to form a common vagina leading to vulva.
• In didelphic forms, one gonoduct may be directed anteriorly and other posteriorly (amphidelphic) or both may be directed anteriorly (prodelphic), or posteriorly (opisthodelphic).

Pro-monodelphic Opistho-monodelphic Pro-didelphic Amphidelphic

Figure 6.1 Different arrangements of tubular reproductive organs in various female nematodes

Male Reproductive System:

• Among plant parasitic nematodes, males generally have a single genital tract (monorchic), butsome genera may possess two genital tracts (diorchic).
• Various parts of male genital tract are: testis, seminal vesicle, vas deferens, cloaca and cloacal aperture.
• Sperms are formed in the testis, and may be temporarily stored in the seminal vesicle.
• Vas deferens joins posteriorly with rectum to form cloaca.
• A pair of hard curved structures, the spicules are located in a cloacal pouch .
• The spicules are protrusible and help in the insemination of females during mating.
• The movement of spicules is guided by a sclerotized plate-like structure, the gubernaculum.
• A flap like structure called bursa is usually present covering the tail region.
• Bursa helps to clasp the female during mating.

Figure 6.2 Male Reproductive System