How do insects reproduce? Characteristics and Stages

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Simon Doyle
How do insects reproduce? Characteristics and Stages

The insects reproduce through physiological processes that include the participation of a male and a female specimen, with some exceptions present in certain species. Fertilization by a male is one of the most common processes.

A large part of the insects are considered oviparous, being through eggs the main way of generating offspring that allow the multiplication and survival of the species.

Reproduction between insects is preceded by processes of copulation, union and cell fusion that will lead to the formation of the young, under specific conditions depending on the species.

Physically, the reproductive system of insects is at the level of the abdomen, with different qualities between male and female specimens..

Insects have their own glands and ducts, as well as ovaries or testes, internal or external. Male insects have their own sperm, with which they fertilize the female genitalia.

The large number of species of insects around the world has generated a whole field of study regarding the reproductive processes that exist between them..

These reproductive processes have undergone evolution and changes, depending on the conditions of the environment in which the insects have lived..

Five reproductive processes of insects

1- Viviparity

The most common process, carried out by a large number of species. It consists of fertilization and embryonic development in an egg within the female's body, which hatches inside once developed, resulting in a small larva that is expelled to the outside with life..

Embryonic development within insects, especially their eggs, has the characteristic of presenting membranes resistant to conditions such as drought, which allows the internal development of the larva or nymph regardless of external conditions..

A variant of viviparity is ovoviviparity, in which the eggs are formed inside the insect, and only hatch shortly after being expelled from the host organism. This variant is observable in cockroach species such as Blaptica dubia; other species of cockroaches reproduce by regular viviparism.

Coleoptera in coital phase.

2- Parthenogenesis

It is another process present in a good number of insect species. It consists of the ovular development inside a female without the need for the ovum to have been fertilized by a male.

Some species resort to this process as the only mode of reproduction, while others alternate it with other processes, such as the viviparous, depending on the conditions..

This asexual reproduction method, also known as virginal reproduction, can be present in species of insects such as beetles and aphids..

Parthenogenesis is not an exclusive reproductive process of insects; reptiles and plants can also carry out these types of mechanisms.

There are three forms of parthenogenesis. The first is arenotosis, produced when the offspring consist solely of male specimens. The second is telotosis, when the offspring consist solely of female specimens..

And the third is amphytosis, in which sexually unfertilized eggs can give rise to both male and female specimens..

Ant larvae, one of the insects that reproduce through parthenogenesis.

3- Paedogenesis

Considered a rare process, it manifests itself when reproduction occurs without the host having reached full maturity.

It consists of the multiplication of larvae, without the main one having reached maturity, which results in a new set of larvae devouring the mother in their own development.

In summary, larvae are capable of being born pregnant inside a female insect, so the number of larvae or pupae resulting from this entire process can be much greater than that resulting from a normal reproductive process..

Can occur in beetles, worms, and mosquitoes.

The larvae of the species Micromalthus debilis can hatch from eggs or are born alive within pedogenic female larvae. David R. Maddison / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)

4- Polyembryony

Polyembryony is a very particular case within the reproduction of insects. It consists of the embryonic multiplication of a single egg; of this, from two to a large number of embryos can be produced at the same time.

It is usually carried out in species such as wasps, which require a large number of individuals to carry out their natural functions, among which the consumption and control of other pests stand out..

Parasitic wasp nest with larvae. Image: pxfuel.com

5- Hermaphroditism

Considered the rarest of all reproductive processes, it consists of the development and presence of two sex cells (male and female) in the same insect. This condition can be observed in species such as earthworms.

The reproduction process between hermaphroditic individuals has peculiarities that vary according to the species of insect. These particularities, even today, continue to be investigated.

Copulating snails. Although they are hermaphrodites, they cannot self-fertilize, so they turn to another being of their species for reproduction. Image Wikimedia Commons

The four stages of the reproductive process

1- Copulation or copulation

Considered the first step to guarantee the perpetuation of the species, it occurs when a male specimen is about to fertilize the ovule of a female specimen through a sexual process..

The duration of this stage varies between species, and can last from a few minutes to hours..

During this phase, variables such as polygamy - when a male copulates with several females - and polyandry - when a female does the same with several males can be observed..

2- Fertilization

As in other living beings, it simply consists of the union of the ovum and the sperm.

Fertilization is always carried out in the female's body, except in those cases in which a process of parthenogenesis or hermaphroditism is manifested.

3- Development of the eggs

Insect eggs do not usually have the same characteristics as other animal eggs, not even among the same species or families of insects.

The egg is usually developed covered with a system of membranes that guarantee the nutrition and protection of the larva..

The development process of an insect egg is usually much faster than any other living being.

"Chorion" is the name given to the protective layer of the egg, under which are the membranes known as serosa and amnion, which are responsible for transmitting nutrients.

4- Laying the eggs

This is the final stage, which can occur quickly, after the copulation process, or much later..

Depending on the reproductive characteristics of the insect, the larvae are expelled already alive from the inside of its body, or the eggs are left to hatch at a later time, not too far away..

References

  1. Authors, C. d. (1994). Plant Health. City of Havana: Editorial Pueblo and Education.
  2. Engelmann, F. (1970). The Physiology of Insect Reproduction: International Series of Monographs in Pure and Applied Biology: Zoology. Pergamon Press.
  3. Gullan, P., & Cranston, P. (2005). The Insects: An Outline of Entomology. Oxford: Blackwell Publishing.
  4. Leopold, R. A. (1976). The Role of Male Accessory Glands in Insect Reproduction. Annual Review of Entomology, 199-221.
  5. Raabe, M. (1987). Insect Reproduction: Regulation of Successive Steps. Advances in Insect Physiology, 29-154.

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