Reproductive System of Cockroach: Cockroach!! Have you seen these insects roaming in your kitchen? How do these insects reproduce? Do cockroaches even have a reproductive system? Do they reproduce by asexual or sexual means? The cockroaches belong to the largest Animal phylum called Phylum Arthropoda and the largest class Insecta. The reproductive system of cockroaches is responsible for the process of reproduction in male and female cockroaches.

Both male and female cockroaches are born through the reproductive system. Cockroaches are dioecious (unisexual), meaning males and females are exhibited separately. If you want to know more about the reproduction process in cockroaches, you should refer to this article till the end. This article covers the male and female cockroaches’ reproductive structures. Read on to know more about the Reproductive system of Cockroaches.

Reproductive System of Cockroach: Organs, Diagrams, Definitions

The cockroaches are dioecious/unisexual creatures. The male reproductive system of cockroaches consists of a pair of testes, vas deferens, utricular gland, the accessory gland in the male reproductive system of cockroach, ejaculatory duct and phallic gland whereas the female reproductive system consists of a pair of ovaries, oviduct, genital chamber, vagina and colleterial glands. Copulation happens during the night times in summer. The fertilised egg called ootheca hatches into a nymph, which gradually grows into an adult through the process of moulting. Before dwelling in detail on the reproductive system of cock roaches, let us first take a look at the position of cockroaches in the animal kingdom.

Cockroach in the Animal Kingdom

Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Blattodea
Genus: Periplaneta
Species: americana

Fig: Cockroach

Sexual Dimorphism of Cockroach

The cockroaches show sexual dimorphism as males and females have slightly different morphology.
Anal style: In male cockroach pair of anal styles arises from the ventral side of the \({9^{{\rm{th}}}}\) segment, whereas anal style is absent in the female. It has a sensitivity to touch.

Fig: Sexual Dimorphism in Cockroach

Male and Female Reproductive System of Cockroach

Cockroaches are unisexual animals (dioecious), and both sexes have well developed reproductive organs.

Fig: Reproduction in Cockroach

Male Reproductive System of Cockroach

The male reproductive system of cockroaches consists of a pair of the testis, vas-deferens, ejaculatory duct, mushroom gland, seminal vesicle, phallic gland, genital pouch and external genitalia.
i. Testis: The male reproductive system consists of a pair of trilobed testis, one on each side of the \({4^{{\rm{th}}}}\) to \({6^{{\rm{th}}}}\) abdominal segments.
ii. Vas-deferens: From each testis, a vas-deferens arises that passes down and connects to the seminal vesicle. This opens into the ejaculatory duct.
iii. Seminal vesicles: The vas-deferens dilates to form a seminal vesicle which helps in the storage of sperms. It is made up of many white sacs which are meant for the storage of sperm. The sperms are glued together to form spermatophores.
iv. Ejaculatory Duct: The two seminal vesicles unite to form a wide glandular and muscular duct called the ejaculatory duct. During copulation or meeting, the spermatophores move down the ejaculatory duct, which opens to the outside by the genital pore present ventral to the anus.
v. Mushroom Gland: The seminal vesicles bear a number of finger-like projections forming characteristic mushroom-shaped glands in the \({6^{{\rm{th}}}}\) to \({7^{{\rm{th}}}}\) abdominal segments. The secretion of this gland nourishes the sperms.
vi. Genital Pouch: The genital pouch is situated at the end of the abdomen and is formed by the \({9^{{\rm{th}}}}\) and \({10^{{\rm{th}}}}\) tergum and ventrally by the \({{\bf{9}}^{{\bf{th}}}}\) sternum. It contains genital pore, dorsal anus and gonapophysis.
vii. External Genitalia: The external genitalia is represented by the chitinous asymmetrical structure called male gonapophysis or phallomere, which surrounds the male gonophore (genital pore).

Fig: Diagram of male reproductive system of cockroach

Reproductive System of Female Cockroach

The female reproductive system of cockroaches consists of a pair of ovaries, oviduct, vagina, spermatheca, collaterial glands, genital pouch and external genitalia.
i. Ovaries: The female reproductive system includes a pair of ovaries present in between the \({2^{{\rm{nd}}}}\) to \({6^{{\rm{th}}}}\) segments of the abdomen. Each ovary is formed by a group of ovarian tubules that contains rows of ova in various stages of development.
ii. Oviduct and Vagina: The ovary continues down in the form of a short, muscular tube called an oviduct. The right and left oviduct units form a single median oviduct, also called the vagina, which opens into the genital chamber.
iii. Spermatheca: A pair of spermatheca present in the \({6^{{\rm{th}}}}\) segment opens into the genital chamber, and it is used for storing the sperm. The left spermatheca is large and functional, while the right spermatheca is reduced and non-functional.
iv. Genital Pouch or Chamber: The genital pouch is a sizable boat-shaped structure surrounded by three pairs of chitinous plates that help in copulation, deposition of the egg. It is formed by the \({{\bf{7}}^{{\bf{th}}}},{\rm{ }}{{\bf{8}}^{{\bf{th}}}}\) and \({{\bf{9}}^{{\bf{th}}}}\) abdominal segments. It is divided into two chambers. The smaller chamber is called the genital atrium and is opening for the collaterial gland, spermatheca and opening of the common oviduct. Its large posterior part is called the vestibulum.
v. Collaterial Gland: Collaterial glands are present on either side of a genital chamber into which they open. Collaterial glands help in the formation of egg cases or ootheca. The ootheca is a dark reddish to the blackish-brown capsule, about \(8\,{\rm{mm}}\) long. They are dropped or glued to a suitable surface, usually in a crack or crevice producing \(9\) to \(10\) ootheca, each containing \(14\) to \(16\) eggs.
vi. External Genitalia: The gonapophyses contains three chitinous plates.

Fig: Female Reproductive System

Development in Cockroaches

i. The development of P. americana is paurometabolous, i.e., there is development through a nymphal stage.
ii. The nymphs grow by moulting about \(13\) times (in Periplaneta americana) and about \(6\) times (in Blatta orientalis) to reach the adult form, which is regulated by various glands.
iii. The period between two moulting is called stadium.
iv. Behind the brain, the rod-shaped paired structures called corpora cardiaca are present, which secrete growth hormones.
v. Corpora allata are small rounded paired structures situated just behind the corpora cardiaca.
vi. In cockroaches, the hormone neotinin, now called juvenile hormone, is secreted by corpora allata.
vii. Prothoracic glands are large irregular paired glands, located in the prothorax and secret a hormone called ecdysone or moulting hormone, to control ecdysis (moulting of the body wall) of the nymph.
viii. These glands degenerate after metamorphosis.
ix. The next to last nymphal stage has wing pads, but only adult cockroaches have wings.

Summary

The cockroach is a nocturnal, omnivorous animal. It belongs to the kingdom Animalia, phylum Arthropoda and class Insecta. The reproductive system is the system that is involved in the process of reproduction. Through this article, we understood the male reproductive system of cockroach consists of a pair of testes, vas-deferens, ejaculatory duct, the external genitalia, etc., and the female reproductive system of cockroaches consists of a pair of ovaries, genital pouch, collaterial glands, vagina, spermatheca, etc. We also got to know that cockroaches are unisexual animals and show sexual dimorphism. Nymph do not have wings, but the changes develop a structure called a wing pad. This mode of cockroach development by various nymphal stages is called paurometabolous.

FAQs on Reproductive System of Cockroach

The most frequently asked questions on Reproductive System of Cockroach are answered below:

Q.1: Do cockroaches lay eggs? Ans: Yes, cockroaches are oviparous and hence lay eggs.

Q.2: What is the function of female Gonopore in cockroaches? Ans: Gonopore acts as a genital pore and is an opening of a common oviduct.

Q.3: How many Phallomere are there in a cockroach? Ans: There are three phallomeres in female cockroaches and six phallomeres in male cockroaches.

Q.4: What is Phallomere in cockroaches? Ans: The genital aperture in males and females is surrounded by some sclerites called Gonapophyses or Phallomeres. Phallomere is a chitinous asymmetrical structure that acts as the external male genitalia which surrounds the male gonopore. Phallomere assists in opening the gynatrium of the female cockroaches.

Q.5: How many ovaries are present in the female reproductive system of cockroaches? Ans: The female reproductive system of cockroaches consists of two large ovaries.

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