They conquered all habitats (except oceans and seas), adapting to the most difficult conditions of existence. They can be found everywhere: in cities, forests, steppes, swamps, deserts and taiga. Highly organized individuals form the most extensive class - insects, which in their species diversity and number surpass all other animals on the planet. And it is precisely the representatives of this class that play a paramount role in the multi-link food chain, in its subtlest elusive processes, as well as in soil formation, pollination of plants and environmental sanitation.
Ancient organism
It was somewhat difficult for scientists to determine the origin of the class of insects. The main problem was the absence of their fossils so that phylogenetic relationships could be identified. For a long time, on the basis of morphological comparisons, centipedes were considered to be closely related to insects. But the construction of phylogeny (the development of the body over time) and fresh morphological studies have indicated that insects are much closer to crustaceans, and not to millipedes.
Crustaceans are familiar from sediments of the early Cambrian period (about 541 Ma), insects are found in the fossil record only in the Devonian system (about 419 Ma). The assumption of their origin from one ancestor contains a time interval of more than 100 million years, in which insects should have already existed. Recent morphological comparisons and evolutionary reconstructions based on genomic sequences confirm that insects are indeed found as descendants of crustaceans. According to analyzes, insects branched off crustaceans in early Devon (or late Silurian). This verdict is consistent with both paleontological data and the resulting estimate based on molecular clocks.
Progressive group
According to various sources, the modern fauna numbers from 900 thousand to 2 million species of insects. Some forecasts report that the number of existing species may reach 5 million or more. There is every reason to believe that such figures can be quite real, given how intense the discoveries of new organisms are at present. In Russia, insects are estimated to be between 70, 000 and 100, 000 species.
The class of insects represents terrestrial animals, as a rule, of tiny sizes, in which the body has a clear division into the head, chest and abdomen, and the main limbs (3 pairs), which are used for movement, are located on the thoracic section. The breathing process is performed using the tracheal system or the entire surface of the body (skin). Representatives of this class differ in body configuration, size and shape of the eyes, the size of the antennae and other signs. In particular, their striking diversity is revealed in the oral organs and limbs. For example, the mouth organs in May beetles are gnawing, and in mosquitoes, stinging-sucking; or hind limbs in grasshoppers are hopping, and in swimming beetles, swimming. All structural features of insects developed as a consequence of adaptation mechanisms to certain living conditions.
Of the 40 orders of insects, 5 are the largest, representatives of which also live in Russia: coleoptera (leaf beetle, ladybug, stag), dipterans (midges, horseflies, mosquitoes), lepidoptera or butterflies (mulberry silkworm, meadow moth, room moth), half-winged or bedbugs (leaf-leaved hilt, bug bugs, Siberian cruciferous bug) and hymenoptera insects (wasp, bee, bumblebee).
Squad beetles or beetles
Beetles are the largest group not only among insects, but also living creatures in general. The detachment has more than 400 thousand species, and hundreds more are being added annually, so it is very difficult to give a true assessment. Beetles are common in all latitudes, with the exception of Antarctica and the highest mountain peaks. In Russia, the insects of this order are represented by about 14 thousand species from 155 families.
According to the name of the detachment, a distinctive feature of beetles is the presence of strong leathery elytra (elite), developed from the upper pair of wings. The original armor bears the protective function of the webbed lower wings in those minutes when the insect is not in flight. At the same time, its elytra closely adjacent to each other, forming a suture line. Also, the body of the beetle, in particular the head and pronotum, has a chitinous coating.
In terms of variety in forms, sizes and colors, this squad has no competition. Their famous representatives on the territory of Russia are: ladybugs, ground beetles, bark beetles, weevils, rhinoceros beetles, Colorado beetles, dung beetles and many others. The size of the beetles can vary from less than 1 mm (pero-wings) to 9 cm (male deer beetle).
Diptera insect squad
According to the number of species, this order of insects takes the fourth place, passing the coleoptera, Lepidoptera, and Hymenoptera forward. The name "two-winged" speaks of the main feature of the order: the preservation of only one front pair of wings. The second pair in the process of evolution was modified and is now represented by club-shaped outgrowths (buzz beetles). Currently, science has described about 200 thousand species of dipterans from 150 families. In Russia, the most famous representatives of the detachment are: flies, mosquitoes, mosquitoes, biting midges, horseflies and gadflies.
In the group of dipteran insects, a considerable variety of colors, sizes and shapes of the body is noted. Moreover, the body shape can be both oblong and slender, and compactly short, as in some parasitic species. But despite the great variety, dipterans have common features: adult individuals have a sucking or licking type of oral apparatus (proboscis), developed faceted eyes, thin sensitive integuments, and 5-segmented paws. Ontogenesis of insects proceeds with a complete transformation.
Lepidoptera squad
The insects of this detachment are valued with no less passion than works of art. Even the ancient Romans believed that Lepidoptera (butterflies) were formed from inflorescences of plants that had come off the stems. Their wings are the most important feature: they have a dense cover of chitinous scales, the structure and location of which determine the originality of color. According to various estimates, butterflies currently number over 200 thousand species, out of more than 200 insect families. About 9 thousand species of the detachment live in Russia, well-known representatives among them are: urticaria, cabbage, cat's eye, dawn, meadow jaundice, wine hawthorn and others.
Another significant feature of Lepidoptera is the structure of the oral apparatus. Most butterflies have a thin and long proboscis, a highly specialized sucking organ, which was formed from modified lower jaws. In some species, the proboscis may be underdeveloped or absent. Some lower representatives of the detachment preserved a gnawing (initial) oral apparatus.
According to the systematization, 3 suborders are noted within the detachment: maxillary, equal-winged and diverse-winged. The latter includes most species of Lepidoptera. In addition, there is a conditional division of butterflies into diurnal (maceous) and nocturnal (heterosexual).
Hymenoptera Insect Squad
The order of insects with membranous wings is second only to beetles and butterflies in species diversity. According to various conclusions, it numbers from 150 to 300 thousand species. In the fauna of Russia there are more than 16 thousand species of hymenoptera. These include both primitive cattails and sawflies, as well as insects with a more complex biology and highly organized nervous system - bees, wasps and ants.
The following distinctive features are distinguished in the description of the species of this order: 4 membranous wings have a loose network of veins, are also found without them (there are also wingless forms); the oral apparatus of the gnawing-licking (bees) and gnawing (ants, wasps) types; development with complete transformation. Many hymenopteran insects live in communities, and some of them are characterized by polymorphism. The composition of such a family is represented by one or several queens, a small number of males and many working individuals (barren females). These species are characterized by nervous activity with predominant instinctive actions.
Hymenoptera play an important role in nature, and also have important economic value. Among them there are dangerous plant pests (nut growers, seed-eaters, horn-tails), predatory forms (ants, wasps) exist, and human allies (bees, bumblebees) are also present.
Squad semi-winged
Bugs or semi-rigid-winged birds have populated all possible land biotopes, penetrated into fresh waters, and such as the Halobates water striders have also mastered the open ocean. This is quite a diverse and numerous detachment, which, according to recent estimates, has more than 42 thousand species of insects. About 1.5 thousand species live in Russia, of which a significant part is concentrated in the southern regions (marble bug, railing, tropical bug, lace-making).
Hemopterans have two pairs of wings, which are laid at rest, covering the abdomen from above. The anterior pair of wings (elytra) is leathery at the base and membranous at the apical part (hence the name of the order), the hind wings are fully membranous. The oral apparatus is represented by the piercing-sucking type, in the form of a jointed proboscis. All representatives of the group also have odorous glands, the secretions of which carry a specific smell. In an adult, the openings of the glands go to the posterior thorax, in nymphs (larval stage of development) - in the abdominal segments. Semi-winged animals have a development with incomplete transformation.
Among the bugs, both herbivorous forms and predators (hunter bugs) are observed. Some species are ectoparasites of mammals and humans (bed bugs).
Predatory species
The activity of predatory insects (entomophages) helps to maintain and maintain balance in nature. Often they turn out to be the main regulatory factor that restrains the excessive reproduction of some herbivorous species.
Mantis. When describing an insect, the front legs are the main sign: the thigh and lower leg form a kind of grasping apparatus, acting like a scissor. Adult individuals feed on grasshoppers, flies, small butterflies, and the larvae are mainly aphids. Praying mantises serve as a classic example of the behavior of "waiting for predators."
Ladybug. The diet of adult insects and their larvae are: spider mites, aphids, eggs and small butterfly caterpillars. These predators have a very good appetite. One larva during its development absorbs up to 600-800 aphids, and an adult is able to eat up to 40 aphids per day.
Coleoptera ground beetles. In the description of predatory species of the family, a long upper jaw similar to a sickle (mandible) is distinguished, with which they firmly hold the victim. Insects move nimble along the surface of the soil, destroying snails, caterpillars, slugs, phytophages and many other pests.
Predatory insects are an important biological factor in the control of parasites. They are successfully used in agriculture, protecting fruit orchards, vegetable fields and crops of cereal crops.
Endangered insects of Russia
According to researchers, at the moment there is an active decrease in the number of 41% of insect species, and this figure will continue to grow every year. In Russia, 110 species of insects now live, which are under special protection and are included in the Red Book.
Wax bee. The species range is rather narrow in Russia: the south of the Far East and possibly on Sakhalin. Today, the number is critically low: no more than 40-60 families are recorded in nature.
Clanis is wavy. A butterfly from the hawthorn family is found in the south of Primorsky Krai. The numbers are very low and subject to significant fluctuations.
Barbel of Heaven. It is preserved in the Ussuri-Primorsky region in forests from Partizansk to Khasan, as well as in the vicinity of Shkotovsky, Terneysky districts and near the settlements of Kaimanovka, Kamenushka and Nikolo-Lvovskoye. The view is marked by single specimens.
Steppe Bumblebee. It is considered a characteristic element of the insect fauna of forest-steppes and steppes. In Russia, the species is settled in the southern Baikal region and the extreme south of the Far East. The number is low.
Multiple studies have revealed that the main cause of extinction of insects is the change or disappearance of their habitat. Another important factor was environmental pollution by pesticides and insecticides.
