From Cells to Offspring: The Secret Lives of Nematodes


Updated: 4 Feb 2024

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Hey there, buddy!

Have you ever wondered how nematodes make more nematodes? What’s their way of reproducing? And is it true that they do not produce asexually?

Well, guess what? Nematodes can reproduce in a couple of ways – either on their own (parthenogenetic) or with a partner (amphimictic), but never asexually. If you’re curious about all this, you’re in the right place! 

No more waiting – let’s dive in!

I realized that nature had invented reproduction as a mechanism for life to move forward, as a life force that passes right through us and makes us a link in the evolution of life. Rarely seen by the naked eye, this intersection between the animal world and the plant world is truly a magic moment. Louie Schwartzberg

Reproduction

The reproduction in nematodes is never asexual. In amphimictic species, males are typically found in higher numbers and are non-parasitic. However, in parthenogenetic nematodes, males are present in very low numbers.

Examples of amphimictic species include Anguina, Globodera, Hoplolaimus, Helicotylenchus, Rotylenchus, and Hirschmanniella. On the other hand, examples of parthenogenetic nematodes include Radophlus, Meloidogyne, Ditylenchus, and Heterodera.

The life cycle is generally completed in 2-5 weeks, but this duration can vary from egg to egg. Seinura celaris wraps up its life cycle in just 2-5 days. On the other hand, Xiphinema diversicaudatum takes a year or more.

The occurrence of the life cycle also varies among nematodes. Aphelenchoides species might go through 10-15 generations, Meloidogyne species go for 3-5 generations, and Anguina species keep it simple with just one generation in a cozy 3-4 month season.

The table below provides information on the fecundity rates and life cycle durations of certain nematodes.

Life Cycle Durations and Fecundity Rates of certain Nematodes.
NematodeDuration of life cycleFecundity (Eggs/Female)
Radopolus similis20-25 days10-32
Meloidogyne spp.3-4 weeks300-900
Aphelenchoides spp.10-15 days20-40
Pratylenchus penetrans4-11 weeks30-40
Rotylenchulus reniformis25 days50-75
Heterodera spp.3-9 weeks300-600
Tylenchulus semipenetrans4-8 weeks40-90
Hoplolaimus indicus26-27 days14-20

Reproductive System

The differences in appearance between males and females are known as sexual dimorphism. Nematodes are either bisexual or dioecious, with sexes identified by primary and secondary sexual characteristics.

Males are characterized by the presence of caudal alae or bursa, genital papillae, and spicules located in the posterior part of the body near the anal region. Meanwhile, females can be identified by the presence of the vulva and vagina, both situated in the posterior part of the body.

Male Reproductive System

It is subdivided into different regions.

  • Testes
  • Seminal vesicle
  • Vas deference
  • Cloaca
  • Spicules
  • Gubernaculum
  • Caudal alae

Testes

Some nematodes have single testis but some have two. These testes are situated at the distal ends and comprise a germinal zone and a growth zone. Male nematodes with one testis are called monorchic and male nematodes with two testes are called diorchic. Sperms are produced in the testes.

Seminal vesicle

After the testes, you’ll find a seminal vesicle which is a swollen portion. Sperms are stored in this portion.

Vas deference

It is a conducting tube. It is muscular and glandular.

Cloaca

It is a common hole or opening of the reproductive system and the anus. Usually, sperms come out through it.

Spicules

It’s like a pair of hook-like or throne-like structures right inside the cloaca, creating a pathway for sperms.

Gubernaculum

It is a hard structure that supports and guides spicules out of the cloacal opening.

Caudal alae

It is a wing-like extension at the tail region. It is also known as bursae. It is used to grip the female during sex.

Female Reproductive System

It is subdivided into different regions.

  • Ovary
  • Spermatheca
  • Oviduct
  • Uterus
  • Vagina
  • Vulva

Ovary

Some female nematodes have a single ovary and some have two ovaries. Eggs are produced in the ovary which are present at distill ends. 

Females which have only one ovary are called monodelphic. Whereas, females which have two ovaries are called didelphic. If the female genital opening is in the center then it has 2 ovaries and if the genital opening is on the side, it has one ovary.

Spermatheca

This portion receives semen from the males and saves it.

Oviduct

A fertilized egg passes through the oviduct. It is the passage of the egg from the ovary to the uterus.

Uterus

It is the organ that contains fertilized eggs. It is the tract between the oviduct and the vagina. 

Vagina

It is the portion of the female reproductive tract that connects the vulva with the uterus. Sometimes, it flexes its muscles to push out eggs.

Vulva

The female genital opening is called the vulva.

Conclusion

In wrapping up this exploration, we’ve taken a deep dive into the fascinating world of nematode reproduction. We have tried to make your concepts clear with our detailed study on nematodes. 

We have discussed in detail and accessible manner the duration of the life cycle of nematodes varying from egg to egg. Every detail of the male and female reproductive system of nematodes is subdivided to make things easy.

Got questions buzzing in your mind? Don’t be shy—hit us up! Whether you’re curious about a specific detail or just want to chat about nematodes, we’re here for you. Your queries are our command, so feel free to drop us a line. We’re excited to be your nematode companions on this journey!

Feel free to Contact Us, and we will be delighted to offer our guidance and support.

FAQs

Here we will provide frequently asked questions for quick answers for your assistance.

How do nematodes reproduce?

 Nematodes can reproduce in a couple of ways – either on their own (parthenogenetic) or with a partner (amphimictic), but never asexually.

What are examples of amphimictic nematodes?
  • Anguina
  • Globodera
  • Hoplolaimus
  • Helicotylenchus
  • Rotylenchus
  • Hirschmanniella
What are examples of parthenogenetic nematodes?
  • Radophlus 
  • Meloidogyne
  • Ditylenchus
  • Heterodera
Define the term sexual dimorphism.

The differences in appearance between males and females are known as sexual dimorphism.

Define the terms monorchic and diorchic.

Nematodes with one testis are called monorchic and nematodes with two testes are called diorchic.

Define monodelphic and didelphic.

Females which have only one ovary are called monodelphic. Whereas, females which have two ovaries are called didelphic.

Name the parts of the male reproductive system.
  • Testes
  • Seminal vesicle
  • Vas deference
  • Cloaca
  • Spicules
  • Gubernaculum
  • Caudal alae
Name the parts of the female reproductive system.
  • Ovary
  • Spermatheca
  • Oviduct
  • Uterus
  • Vagina
  • Vulva

Dr. M Awais

Dr. M Awais

This is Awais. I am a phyto doctor. I have studied plants my whole life. Plants are my best friends. I have gathered detailed information about plants. My brilliant team is always ready to accept the challenges. Together, we find the solutions for our clients.

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