Structure and types of antennae of insects. Methodical instructions. External structure of insects. What are antennae
Entomology is the science of insects (the name comes from two Greek words entomon - insect and logos - science). Insects belong to the class insects - Insecta, phylum arthropods - Arthopoda. The class of insects is diverse in the number of species included in it (more than 1 million species), which have diversity morphological features, biological properties, adaptive features and relationships in the environment. The role of insects in nature, human life and the economy of society is no less diverse. In this regard, entomology has now been divided into general entomology and a number of applied scientific disciplines - agricultural, veterinary, forestry, medical entomology, beekeeping, and sericulture.
General entomology is a theoretical discipline that serves as the scientific foundation for the applied disciplines listed above and special disciplines entomological series - biological protection, quarantine, prognosis, immunity and some others. She studies the morphology, anatomy, physiology of insects, biology of reproduction and development, ecological characteristics of insects, systematics and classification of insects.
General entomology as a branch modern biology has accumulated a large stock of knowledge, makes a significant contribution to the development and well-being of society, and seeks ways for reasonable solutions to existing environmental problems.
Insects represent the class Insecta, which belongs to the phylum Arthropoda. This class has a segmented body and jointed walking limbs and bears a pair of antennae. The insect's body is divided into three main sections: head, thorax and abdomen (Fig. 1). Familiarization with the main parts of the body and their appendages is carried out using permanent preparations and the example of the cockchafer.
Rice. 1. The body of the Italian locust with the designation of the main parts
(left pair of wings removed)
To dismember an insect into three sections, you need to lay it on its back, find the sections, then secure the insect with a dissecting needle, which should be inserted in the center between the front and middle pair of legs to the bottom of the Petri dish and, holding the prothorax, using a second needle or scalpel cut off (pull off) the head. After this, insert one needle into the chest near the last pair of legs to the bottom of the cup to hold the insect, and the other needle, holding it obliquely, gradually insert (not to the bottom of the cup, otherwise the wings will interfere with dismemberment) immediately behind the hind legs into the body of the insect and separate the abdomen , pushing it aside. Now you should study each part of the body and appendages on it.
Rice. 2. Insect head: 1 – upper lip; 2 – upper jaw; 3 – casing; 4 – frontal-clypeus suture; 5 – cheeks; 6 – forehead; 7 – antennal fossa; 8 – peephole; 9 – parietal suture; 10 – compound eye; 11 – crown; 12 – occipital suture; 13 – back of the head; 14 – posterior occipital suture; 15 – posterior occiput; 16 – cervical membrane; 17 – lower lip; 18 – lower labial palp; 19 – lower jaw; 20 – mandibular palp
Head(Fig. 2) the insect consists of the forehead (between the compound eyes), the clypeus (to the bottom of the forehead), the crown (above the forehead), and the occiput (the back of the head). On the sides of the head there are temples (above the eyes) and cheeks (below the eyes).
The shape of the head is varied: round (flies), laterally compressed (locusts, grasshoppers), elongated in the form of a rostrum (weevils, tubeworms). There are also different types of head positioning: prognathic, hypognathic and opisthognathic. With the prognathic type, the mouthparts are directed forward, it is characteristic of predatory insects (ground beetles, rove beetles, earwigs); with hypognathic - the mouth parts are directed at a right angle downward, characteristic of herbivorous insects (locusts, many types of beetles, bedbugs); with opisthognathic - the mouthparts are directed at an acute angle downwards and backwards, approaching the front legs of the insect, characteristic of many sucking insects (cycads, aphids, thrips, copperheads (Fig. 3).
The appendages of the head are the mouthparts, antennae and eyes, compound (complex) and simple (ocelli). Compounded eyes consist of numerous small eyes (ommatidia), located on the sides of the head, and perform a visual function. In some males, the flies occupy almost the entire head. Simple eyes, if present, are often three in number and are located in a triangle on the forehead and crown of the head. You should find all the components of the head and appendages on the insect’s head and then familiarize yourself with the main types of insect antennae, using constant preparations.
Rice. 3. Types of head positioning: 1 – prognathic; 2 – hypognathic; 3 – opisthognathic
Rice. 4. Antenna structure: 1 – flagellum; 2 – leg; 3 – scape; 4 – antennal cavity
Mustache or antennae (antennae) represent one pair of jointed formations located on the sides of the forehead between or in front of the eyes in the antennal fossae. They serve as the organ of smell and touch in insects. Often they are larger in males than in females (examine a dissected cockchafer, determine the type of antennae). The antenna consists of a thickened main segment (scapus), a stalk (pedicillus) and a flagellum (flagellum) (Fig. 4). The structure of the antennae varies individual species and groups of insects, and this feature is widely used in the diagnosis and taxonomy of insects.
The following main types of antennae are distinguished (Fig. 5):
1) bristle-shaped– the segments gradually narrow from the base to the apex and then the antennae towards the apex are clearly pointed (grasshoppers, mole crickets);
2) filiform– all segments along the length of the antenna are basically the same thickness (locusts, moths and moths, cruciferous flea beetles);
3) lucid– segments are short and wide, the base of each of them is narrowed (darkling beetles);
4) sawtooth– the upper corner of each antennal segment is somewhat retracted on one side (some click beetles and borers);
5) comb-shaped, or comb-shaped– each antennal segment has a relatively long process on one side (some click beetles);
Rice. 5. Types of antennae: 1 – bristle-like in a cockroach; 2 – filamentous in locusts; 3 – clear-shaped in the May beetle; 4 – sawtooth borer in beetles; 5 – comb-shaped in click beetles; 6 – club-shaped in diurnal Lepidoptera; 7 – capitate in carrion beetles; 8 – fusiform in lepidopteran pests; 9 – lamellar-club-shaped in Khrushchev beetles; 10 – comb-geniculate in stag beetles; 11 – irregular twirling pattern in beetles; 12 – feathery in silkworm butterflies; 13 – bristle-bearing in round-sutured dipterans
6) pinnate– each antennal segment has bilateral outgrowths, and the antennae resembles a bird feather (silkworm butterflies, American white butterfly);
7) club-shaped– the apex of the antennae is thickened (white butterflies, urticaria, rapeseed flower beetle);
8) capitate– the apex of the antenna is significantly thickened and sharply separated from the remaining segments of the antenna (dead beetle);
9) plastic-club-shaped– the mace consists of plates folded in a fan shape (Chafer beetle, Kuzka beetle, Crusader beetle);
10) cranked– the first antennal segment is significantly longer than the others that make up the flagellum, and is directed at an angle to them. Generic-club-shaped (weevils), geniculate-combed (stag beetle);
11) fusiform– gradually thickened in the middle (variegated);
12) bristly– three short and wide segments various shapes, the latter with bristles (house and other types of flies);
13) wrong– the antennal segments are not similar to each other in shape and size, often asymmetrical (some soft-bodied animals).
Rice. 6. Gnawing oral organs: a – upper lip; b – upper jaws; c – lower jaws; g – lower lip; 1 – internal chewing blade; 2 – external chewing blade; 3 – maxillary palp; 4 – stem; 5 – main segment; 6 – tongue; 7 – accessory tongue; 8 – labial palp; 9 – chin; 10 – chin
Laboratory work No. 1
External structure of insects
Target- Study the external structure of insects.
Materials and equipment: collectible specimens of insects (grasshoppers, beetles, bugs), magnifying glasses, dissecting needles, glass slides.
Progress
Examine and sketch the external structure of insects, pay attention to the location of the limbs, wings, and the position of the head relative to the axis of the body.
Find three sections: head, chest, abdomen. Examine the places of their articulation and separate them from each other using dissecting needles. Sketch the dissected parts - head, chest, abdomen.
Examine the structure of the head at 10-20x magnification. Sketch and label all parts of the head and its appendages (vertex, forehead, clypeus, cheeks, upper lip, upper jaws, eyes, ocelli, antennae, labial palp, maxillary palp).
Consider and sketch Various types antennae: filiform, setaceous, bead-shaped, saw-toothed, clavate, pinnate, geniculate, setaceous (Fig. 1).
Determine the types of antennae in the listed insect species: May beetle, grasshopper, striped click beetle, golden bronze bug, turtle bug, white cockroach, red cockroach. To determine the type of antennae, use the attached descriptions and figs. 1.
Thread-like antennae. All segments are cylindrical, i.e., more or less the same width, only at the base they can be somewhat thickened (Fig. 1, a). Example: locusts, some butterflies (moths and moths).
Bristle-like antennae. The segments gradually narrow from the base so that the antennae are clearly pointed towards the apex (Fig. 1, b). The antennae can be long or short. Example: grasshoppers, crickets, mole crickets, cockroaches.
Rosary antennae. They consist of short and wide segments, the bases of the latter are narrowed so that the segments are separated from one another by constrictions; the first (1st-2nd) segments may be elongated (Fig. 1, c). Example: darkling beetles.
Saw-shaped antennae. The segments that make up the antenna have a retracted upper corner and together resemble saw teeth (Fig. 1, f). Example: click beetles and borer beetles. A modification of the saw-shaped antennae can be considered a comb, or comb-shaped, antennae (Fig. 1, g), each segment of which has a process; the processes form a ridge. An example is click beetles from the genus Corymbites.
Club-shaped antennae. Several apical segments are expanded and form a club (Fig. 1, e).
Example: white butterfly, urticaria butterfly. If the antennal club consists of plates folded like a fan, then the antennae is called lamellar-club-shaped (Fig. 1, j).
Example- May beetle and other beetles.
Feathery antennae. Each antennal segment has bilateral growths, decreasing from the base to the apex; in total, the antennae resemble a bird's feather (Fig. 1, h). An example is silkworm butterflies.
Elbowed antennae. The first antennal segment is significantly longer than the remaining segments that make up the flagellum, and is directed at an angle to them (Fig. 1, k). Example: hornet, bumblebee, stag beetle and other species of the longhorned beetle family.
Bristle-bearing antennae consist of three short and wide segments of various shapes; on the last segment there is a seta on the side or at the apex, which may be feathery (Fig. 1, i). Example: housefly and some dipterans.
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Type of nervous system in insects
The nervous system of insects processes signals coming from environment, into electrical impulses. Thanks to this, muscle movements and organ functioning are carried out. Especially a large number of nerve cells located in the head. They form the brain, as well as the second nerve center located under the esophagus, the subpharyngeal ganglion. The three thoracic segments contain nerve ganglia that control the movements of the legs and wings. Eight nerve ganglia located in the posterior part of the body innervate their area of the body. The nerve ganglia are connected to each other and to other nerve centers by nerve trunks. Thus, nervous system insects is built on the principle of a rope ladder. In many insects, the nerve ganglia of the thoracic segments and the posterior part of the body merge into larger ganglia.
How do insects breathe?
By complex system tubes distribute air throughout the insect's body. On each side of the thoracic and abdominal segments there is one respiratory opening. Tracheas and respiratory tracts extend from it, which branch intensively. The thinnest tubes, thousands of times thinner human hair, entangle the surfaces of all insect organs. Large insects such as beetles and butterflies often breathe by tensing and relaxing the back of their body. To prevent moisture from leaving the respiratory tract, the insect closes the respiratory openings with hairs; This eliminates the possibility of getting into them foreign bodies. The trachea is covered from the inside with a cuticle, which is renewed with each change of the shell.
Do insects have ears?
"Drum" skin is present in the body of many insects. This “ear” is often receptive not only to the sounds that people hear, but also to ultrasound. However, it is located not on the head of the insect, but on various parts of its body: in cicadas and some moths, on the back of the body, in other butterflies, in the last thoracic segment. Grasshoppers have “ears” located under the knees on their front legs. Many insects use their ears to communicate: female grasshoppers and crickets find singing males. But insects also have other sense organs that perceive noise. Male mosquitoes use an organ located in their antennae to detect the sounds that females of their species make when flying, and thus find a partner. Cockroaches have long, sensitive hairs on the back of their bodies that can sense sound.
Why do insects have antennae?
The sense organs on the antennae of insects tell them not only the state of the environment, they help them communicate with relatives, find a suitable habitat for themselves and their offspring, as well as food. The females of many insects attract males using scents. Male lesser night peacocks can smell a female from several kilometers away. Ants recognize females from their anthill by smell. Some types of ants mark the path from the nest to the food source thanks to odorous substances that are released from special glands. With the help of their antennae, ants and termites smell the scent left by their relatives. If both antennae pick up the scent to the same extent, then the insect is on the right track. Attractant substances released by female butterflies ready to mate are usually carried by the wind.
Remember the cartoon about Komarov, the one who sang the song “The boy has panties, the cockroach has antennae...”? We'll talk about them, about the mustache. In this part we will look at the classification of antennae, and a little later I will reveal the secret of some behavioral aspects associated with insect antennae.
What are antennae?
The antennae of insects are also called antennae or antennae. And these are modified limbs that have acquired the ability to feel. In total, insects have a pair of antennae. This is an organ of multifunctional analysis, responsible for the sense of smell and touch.
On a spring or summer walk, it would be good to take a magnifying glass and a drawing with you and try to examine and identify the types of antennae of different insects. You can do it even simpler - first take a photograph of the insects, and then enlarge the photo on the screen, then the antennae will be visible even better. But studying with a magnifying glass, making sketches in a travel notebook, is much more interesting. Of course, you haven’t forgotten that for an exploratory walk we need one like this? This is such a fun, exploratory hunt! Of course, we don’t forget about safety precautions; we explain to the baby that there is no need to grab insects with your hands. It’s better to take a large magnifying glass with a long handle.
The antennae consist of segments, which can conventionally be considered tightly fitting beads. Antennas consist of three parts. The first part is the main segment - the scape, or the handle. With the help of the main segment, the antenna is deepened in the antennal fossa on the forehead between the eyes. Motor muscles are attached to the scape (handle), causing the antennae to move.
The second part consists of a large segment of the peddicellum, or stalk. Adjacent to the stalk is the third component of the antenna - the flagellum, or flagellum. The flagellum consists of many smaller segments.
Basically, the antennae are the organ of smell. Smell is one of the leading languages of communication in the insect world, so it is not surprising that one bee antenna contains more than 30,000 receptors involved in the sense of smell.
The sense of smell plays a leading role in the communication of social insects such as ants. If an ant is marked with the smell of a dead ant, then its fellows will treat it as if it were inanimate, and will begin to take it out of the anthill onto a garbage heap, despite the motor protest and waving limbs of the living ant, despite its ability to move independently.
The worse the vision of an insect is, the longer and more magnificent its antennae. In moths this tendency is most pronounced in the form of feathery antennae. Such luxurious whiskers allow you to smell a female at a distance of 2 kilometers! Mosquitoes also have feathery antennae.
Types of insect antennae
Antennae are a systematic feature, that is, their shape is taken into account when determining the type of insect. The filamentous tendril is the simplest model; along its entire length they are thin and of the same width, usually cylindrical in shape, although they can widen at the base.
Worn threadlike antennae locusts, moth butterflies. Modified under the influence of the environment, the filamentous antennae turned into other types of antennas, increasing the success of survival among insects.
Interestingly, even within a species there can be differences in the structure of the antennae between females and males. Typically, males will have more gorgeous breasts. For example, in the meadow moth(Loxostege sticticalis L.) The male's antennae are serrated, while the female's are filamentous.
If the female and male differ from each other in appearance(morphology), then this phenomenon is called sexual dimorphism. Very pronounced sexual dimorphism in chicken birds, and in humans too.
It is by their antennae that you can easily distinguish a grasshopper from a locust. Grasshoppers always have antennae longer than body, and their type will not be filamentous, but bristle-shaped. The beaded members will be wide at the base and more pointed at the apex. Therefore, sometimes this type of antenna is called awl-shaped.
Actually, the cockroach of K.I. Chukovsky is the owner of bristle-like antennae.
If the antennas consist of parts resembling tightly spaced round beads (rosaries), then this beaded antennae. The owner of such antennae was the Flea Bug from V. Bianchi’s fairy tale about the Ant, who was in a hurry to go home.
Many small insects have beaded antennae - midges, gall midges, but there are also quite large insects with beaded antennae, for example, blister beetles.
The beaded antennae of the common blueberry Meloe proscarabaeus
Beaded antennae are characteristic of labiopods, although they belong to the type of tracheal breathers, like insects, but centipedes represent a separate branch.
The leptura beetle will have antennae serrated or serrated. Their beaded members will be triangular in shape, with the sharp part directed in one direction, like the teeth of a saw.
Found in woodcutter beetles scaly type of antennae.
If the teeth are strongly elongated, then such a tendril is classified as comb-shaped (comb-shaped) type, that is, the antennae looks like a comb, a comb. The day hawk moth will have comb-type antennae.
Club-shaped antennae are characteristic of diurnal butterflies; even the name of their group reflects this feature - club-bearded lepidoptera. It’s like two gymnastic clubs adorn the heads of many of our butterflies - the swallowtail, the white butterfly, the urticaria.
There are also mustaches cranked, bend between the stalk and flagellum (on overall picture signatures of parts of the antennae are located on it), such antennas are characteristic of ants and bumblebees.
A kind of cranked variety will be lamellar antennae of bronze beetles, rhinoceros beetles, ladybugs, Kuzek beetles, Khrushchev. These antennae remind me of Brezhnev’s luxurious eyebrows))) Such beetles are united by the tribe lamellar.
The last type of antennae that we will consider today is the bristlecone. These are shortened antennae, part of the flagellum is modified into bristles. Characteristic of short-whiskered dipterans, or, more simply, of flies.
To be continued....
Termites are an infraorder of social insects with incomplete metamorphosis, related to cockroaches. For a long time termites were considered an independent order (2009, in Lately their taxonomic status is debated and considered in the rank from infraorder (2011, 2013) to epifamily (epifamily Termitoidae; 2007) within the cockroaches. There are 2933 known in the world modern looking termites (data for 2013; including fossils 3106 species)
Like all social insects, termites are clearly divided into three main groups: workers, soldiers and individuals capable of sexual reproduction. Worker termites have soft white bodies, typically less than 10mm in length. The eyes are reduced or absent. In contrast, reproductive individuals have a dark body and developed eyes, as well as two pairs of long triangular wings, which, however, are shed after the only flight in the life of the reproductive individual.
Colony structure and behavior Unlike ants, in the most evolutionarily advanced species of termites, caste affiliation is determined genetically. In more primitive species, the caste of an individual depends on what other termites feed it during the development period and what pheromones they release. Asexual reproduction in the form of thelytokic parthenogenesis was found in 7 species of termites, including: Reticulitermes speratus, Zootermopsis angusticollis, Zootermopsis nevadensis, Kalotermes flavicollis, Bifiditermes beesoni. The diploid chromosome set of termites is 2 n=28-56, and in the primitive Mastotermes darwiniensis 2 n=96.
All termites eat cellulose in one form or another, but wood-eating termites are especially responsible for damage to buildings. Cellulose is a rich source of energy, but difficult to digest. Among the symbiotic organisms in their intestines, termites rely primarily on metamonads of the genus Trichonympha, which consume the substances left after digestion. Intestinal microorganisms, in turn, rely on special bacteria, living on their shells and producing some digestive enzymes. This relationship is one of the most beautiful examples of mutualism among animals. Most “higher” termites, especially the family Termitidae, can also produce their own cellulose-processing enzymes, however, they also retain rich microflora in their intestines.
Termites play a role in ecology along with earthworms and ants vital role in the circulation of soil matter, in addition, winged individuals serve as food for numerous predators. It is also believed that the methane released by termites as a result of their activity makes a significant contribution to general action greenhouse gases. In terms of their total biomass (from 1 g/m3 to more than 10 g/m3), termites are comparable to total biomass terrestrial vertebrates. Termites, together with ants, can increase crop yields in regions with dry and hot climates (in experimental conditions in Australia they increased wheat yields by 36%) where earthworms are absent.
Interaction with humans Approximately 10% of termite species are pests, causing losses to human households amounting to billions of dollars per year (up to $20 billion worldwide). Due to their feeding habits, termites have become a real scourge on wooden buildings in some regions. Their secrecy and tactics of eating wood, in which its surface appears completely undamaged, are the reason for their late detection. There is also concern about termites accidentally entering apartments, due to which their range is expanding into those regions where they cannot live openly due to the climate. Once in a home, termites are not limited to wood: anything with a high proportion of cellulose serves as potential food. The consequences of this are sometimes catastrophic, for example, in South America due to the constant presence of termites in cities, it is rare to find a book older than fifty years. .
The structure of the antennae of insects Antennae (or antennae, or snots) are a pair of mobile articulated appendages of the insect's head, extending from the front surface, usually between the eyes. The first segment is called the scape (scapus) or manubrium, the second - pedicellum (pedicellus) or stalk, and all the remaining ones together - flagellum (flagellum) or flagellum. The antenna is attached in the antennal fossa, sometimes surrounded by a narrow ring-shaped antennal sclerite. In the peripheral part of the fossa there is a small outgrowth to which the antenna itself is attached.
The antennae move with the help of muscles attached to the main segment - the scape; the muscles stretch towards it from the tentorium. The aflagellum moves due to the muscles located between the manubrium and the flagellum. In embryogenesis, the antennae develop from the appendages of the 2nd head segment.
Functions of antennas Functionally, antennas are a sense organ; they are responsible for touch and smell. There are insects in which they perform non-standard roles - respiratory organs and prey retention.
Antennae are extremely varied in shape, and some of the most clearly defined types have special names. Several examples are shown in the figure. The variety of antenna shapes allows them to be used in determining the type of insect. The antennae are classified according to their shape: Club-shaped (for example, in the Club-whisker from the Darkling beetle family); Cirrus; Lamellar; Fusiform; Thread-like (for example, in beetles from the Pretender family); Serrated; Rosary-shaped (for example, in the Greater mealworm); Comb; Chaetose; Chaetiferous.
It should also be noted that the structure of the carcass often reflects sexual dimorphism - in males they are usually more developed than in females. In larvae, the antennae, as a rule, are greatly reduced both in terms of length and in terms of the number of segments. All insects have antennae except the order Protura, in which they are lost.