There are a huge number of insects in the world, which can be found both in forests and fields, and in a person’s house. Consider how insects reproduce.
Reproduction features
Insects are characterized by sexual dimorphism, that is, it is quite easy to distinguish between a male and a female in appearance. They have different sizes (at the same time, in many species, females are many times larger than males), differ in color, length of antennae. In some species of butterflies, the females do not have wings.
Communication between heterosexual representatives of the species occurs in various ways:
- With the help of behaviors.
- Sound and color signals.
- Chemically - the release of pheromones.
In certain species, contact between a male and a female is not required for fertilization, such are lower insects whose habitat is rotten wood or soil. How do insects reproduce in this case? Males leave drops of sperm on the ground, and females capture them with special organs (genital appendages) located next to the genital openings. It is this method that is inherent in representatives of the class with incomplete transformation:
- Mantis.
- Cockroaches.
- Bedbugs.
Other insects reproduce by mating individuals of different sexes, this phenomenon is called copulation.
Most representatives of the class are inherent in reproduction with the participation of individuals of both sexes, however, there are exceptions in nature.
Ways
There are five main ways that insects reproduce. Information about them is presented in the form of a table.
Way | His brief description | Examples |
live birth | In the body of the mother, the embryo develops, a larva or prepupa is born. | Some types of flies and gadflies |
Gamogenetic | Individuals of both sexes participate in the process, mating and laying eggs occur. In this way, a large number of insects reproduce. | |
Pedogenesis | Reproduction at the larval stage, larvae develop in her body, which eat the mother's body to get out. The method is typical for Coleoptera or Hemiptera, often alternating with hamogenesis. | Some species of gall midges |
Parthenogenesis | Virgin reproduction, no fertilization. | honey bee, some hymenoptera |
Polyembryony | Riders |
These are the main methods of reproduction of insects found in nature.
Parthenogenesis
Consider which insects are able to reproduce parthenogenetically. These are stick insects, some scale insects, aphids, many types of wasps, ants and bees.
Capable of such reproduction:
- Males, in this case, the phenomenon is called arrhenotoky.
- Females, we are talking about thelytoky.
- Both those and others are amphitokia.
It is customary to distinguish between several types of parthenogenesis, the differences of which are presented in the table.
Short description |
|
Optional | It has a partial character, occurs only under the influence of external factors or with a special condition of the female. |
Cyclical | A striking example is the reproduction of aphids. There is an alternation of generations: virgin and bisexual, in this case, the offspring of a female that has not received fertilization consists of females for a long time, but the growing season always ends with amphitoky or arrhenotoky. |
Constant | It is most often observed in closed ground conditions, under optimal external conditions, in the absence of the need to proceed to reproduction with the participation of both sexes. |
This method of reproduction has an adaptive value, an individual of only one sex is occupied in the process, this helps insects to survive even in adverse external conditions.
Stages of development
Consider how insects reproduce and develop. If the process of reproduction can take place both with fertilization and without it, then development goes through several stages:
- With an incomplete cycle of transformation, it includes three stages: an egg - a larva - an adult (in science it is called an imago). In this case, the structural features of the larva practically do not distinguish it from the imago.
- The full cycle of transformation implies four stages: egg - larva - pupa - imago. The larvae are significantly different from adult insects.
These are the phases of development, it can shed several times, gradually increasing in size.
Egg features
We looked at how insects reproduce. Now we will find out what is the peculiarity of their development in each of the phases.
The eggs of representatives of the class are covered with two shells, they have a very different shape, color and size. Most often in nature there are such forms:
- oval;
- hemisphere;
- barrel.
For example, the eggs of butterflies and flies are most often oval, while those of bedbugs are in the shape of an almost regular ball. Most often they are deposited in small groups - oviposition, but in some species they can be deposited singly.
Classification of larvae
By type of larvae are:
- Imagoid (nymphs) - in insects with As previously mentioned, they differ little from adults, hence the name. Most often they lead a lifestyle similar to adults and eat the same.
- Non-imagiform are present in representatives of the class with complete transformation. They have a simpler structure of eyes and limbs than adults, there may be a completely different structure of the mouth.
Non-imagiform, in turn, are divided into three types:
- Campodeoid - reminiscent of adults, quite active, often predatory.
- Worm-like. Such larvae are large, their body is practically not subdivided into sections, the legs are short or may be completely absent.
- Caterpillars are distinguished by the presence of several pairs of adnexal legs.
These are the main varieties of larvae of representatives of the insect class.
pupal stage
Most often, the transformation of a larva into a pupa occurs in the soil, less often - inside or on plants. The insect itself remains immobile, but inside it an intensive process of formation of imago tissues takes place. By the end of its development, the pupa becomes very similar to the adult, however, it is still possible to distinguish the pupa from the imago: the latter lack an additional protective shell.
Curious facts
Having learned how insects reproduce, let's get acquainted with a selection of interesting facts:
- Bees mate only once in their lives.
- In mosquitoes, mating occurs in autumn, but females lay eggs only in spring, that is, a rather long time passes between copulation and fertilization.
- Under certain circumstances, almost all insects are able to reproduce parthenogenetically, with the exception of dragonflies and bedbugs.
- The process of mating ladybugs can last more than 10 hours.
- After mating, the female praying mantis often eats the male to make up for the lack of nutrients in the body.
We briefly reviewed how insects reproduce. There are quite a few ways, they help populations survive and spread, despite adverse environmental conditions.