Ground beetles

Ground beetles are a very large family, which has a large number of genera and species, which are often difficult to distinguish, and therefore many different signs are used for diagnosis: color, body shape, external structure, surface structure, size, genital structure and hetotaxia are taken into account ^{[ 2]} .

The color of ground beetles is very diverse, mainly in dark colors, often with a metallic tint. Often when black or dark, a rainbow (iridescent) tint occurs, which is created by a micro-sculpture from thin transverse lines ^[2] .

Individual taxa, mainly at the level of subfamilies and tribes, have a characteristic body shape. Sometimes the body shape is very different from the usual for ground beetles: species of the genus Omophron , which live on sandy beaches, resemble ladybirds or some black beetles in their round shape; representatives of the genera Drypta , Demetrius and Odacantha living on grass stems have an elongated, stem-shaped body shape; burrowing species from the Scaritinae subfamily, as well as some other groups, are characterized by a neck-shaped ligation between the anterotaxis and the back of the body, as well as broad, anterior tibiae with denticles. A peculiar body shape in species from the genera Cicindela , Elaphrus , Notiophilus and some others ^[2] .

Sizes from very small, barely exceeding 1 mm, to very large, almost 10 cm.

The shape of the body is very diverse, and although most species have an elongated more or less oval body, some groups are characterized by a round shape in the form of a biconvex lens or a flat leaf-shaped body. Cave species often have a strongly convex body with a huge head and a deep constriction at the base of the pronotum , which gives them some external resemblance to ants .

Coloring is most often blackish or metallic; pigmentation is characteristic only for certain, mostly epiphytic and driving groups of ground beetles. Hidden living species are characterized by depigmentation of the body.

Head

The head is pulled slightly into the prothorax or up to the eyes ^[2] , directed forward and ends with strong pointed jaws , the shape of which depends on the type of food. A number of predatory groups are characterized by long sickle-shaped mandibles , well adapted to hold the prey. On the contrary, herbivorous forms usually have massive and blunt jaws, adapted to the grinding of the plant substrate .

Eyes of various sizes, from very large (in species with daytime or predominantly twilight activity) ( Cicindela , Elaphrus , Notiophilus , etc.) to strongly reduced ( Leptopaphiama , some Trechus , etc.) ^[2] . In species leading a nocturnal lifestyle, eyes of medium size, in numerous soil or cave forms, are more or less reduced until their complete disappearance. No eyes ^[2] .

The temples are sometimes highly developed, and the head behind them is neck-shaped narrowed. More often the forehead on the sides, usually in the anterior half of the forehead there is an impression: if it is short and wide, then it is called the frontal fossa, if long it is called the frontal groove. Often the frontal grooves are very well developed, in the front part they penetrate the sides of the clypeus, in the back side they reach the temples. The clypeus is usually more or less clearly separated from the forehead by a clypeal suture ^[2] .

The upper lip is of various shapes, usually able to move under the clypeus, less often connected to it motionless. The chin is separated from the submentum , in the middle of the front anterior margin with a notch, usually provided with a middle tooth; the latter triangular, or blunt at the apex, or deeply dissected, is often absent. The lateral chin lobes on the inner edge are usually equipped with borders ( epilobes ). Sometimes on the chin, for example, in the genera Clivia , Dyschirius , etc., near the middle or on the base are two holes (chin holes) of the lower lip sensory organ, which, according to Jeannel, serves ground beetles as an organ of hearing. Almost always on the chin there is one or more pairs of bristle-bearing pores ^[2] . The tongue at the apex has two or many setae; paraglosses, naked or pubescent, adjoin its sides. Mandibles are usually strong, sometimes very large, in the lateral groove sometimes with one or more teeth ( retinacula ), in the front half sometimes also carries teeth of various shapes. Maxillae with a hook-shaped line bent at the apex, palp-shaped 2-segment galeia and 4-segment maxillary palp. Labial palps three-segmented. The last segment of palps is sometimes greatly expanded to the apex (axiform shape), ax-shaped, triangular; sometimes, on the contrary, it is strongly reduced to a small needle-shaped appendage on top of a large penultimate segment ^[2] .

Antennae (with the exception of Paussinae ^[2] , in which tendrils usually acquire a bizarre shape) are 11-segmented, filiform and clearly visible, the first segment is usually provided with one, rarely several bristles; the remaining segments, with the exception of the latter, are equipped with a nimbus of several setae at the apex. Several basal antennae segments are usually bare, the rest are covered along the entire or almost the entire surface by adjacent hairs ^[2] ; in Lorocera , in addition to the usual fine pubescence, they are covered with separate long setae.

Chest

Pronotum of the most diverse form. Environmental specialization is often reflected precisely in the form of the pronotum, the nature of its articulation with the elytra largely determines the degree of mobility of the anterior part of the body - the narrower the pronotum base, the higher this mobility. Therefore, the most specialized digging species and various types of wells are distinguished by a peculiar tightened body shape. The shield in the vast majority of species is well developed, only in exceptional cases it is reduced - for example, in some cave forms.

Limbs

The legs are usually thin and relatively long, well suited for walking and running; in digging forms, they are strongly thickened and serrated along the outer edge and often provided with teeth and outgrowths. The paws are 5-segmented, hind coxae without femoral tympanum, usually touching at the midline and crossing the first segment of the abdomen . Swivels are well developed, sometimes very long, in exceptional cases even longer than the hips. On the front shins of most ground beetles there is a notch - a special toilet organ designed to clean the antennae. The 4th segment of the legs in epiphytic species is often with a deep notch, into which the claw segment is embedded, thus forming a specialized organ for grasping plants . The same segment in cave species is usually with a filamentous process that helps to attach to the substrate when climbing the walls of caves.

Elytra and wings

Wings with a characteristic, so-called caraboid venation. The degree of development of the wings depends not only on the taxonomic group , but often varies even within the species. In the latter case, depending on the dominance of the corresponding gene , various types of wing polymorphism are observed. Like other insects, short-winged flightless species and / or populations are especially characteristic for islands, mountains, caves, as well as for the most favorable and stable communities in this zone. The nature of the distribution of wing forms can be used to elucidate various questions of the genesis of the group, mapping glacial refugiums , etc. Wings are especially well developed in thermophilic drive groups, for example, horses and Pogonini , as well as tropical woody forms. Many of these species fly so well that they prefer to fly away rather than run away from danger. However, most ground beetles fly rather poorly and use the flight mainly for resettlement, and some species never fly at all.

Elytra usually quite solid, for the most part, almost entirely covering the abdomen , only at the apex sometimes cut off. In wingless species, they can grow together along the seam; usually their surface with longitudinal grooves, which can be punctured. The number of grooves is most often equal to 9, but can increase due to bifurcation or, conversely, decrease; such changes are most often a multiple of 3. On this basis, a rather complex sculpture sometimes develops or the entire sculpture is reduced and the surface becomes mirror smooth.

Abdomen

Abdomen depending on the group with 6-8 visible sternites . Edeagus asymmetric, resting on its side at rest; most often it is a uniformly sclerotized tube, less often its dorsal surface is membranous, or a pair of longitudinal sclerites remains on the sides. Parameres are free, depending on the group, symmetrical or not.

In the vast majority of ground beetles, males are characterized by one or more extended segments on the front and sometimes middle legs, the lower surface of which is equipped with attachment hairs that serve to hold the female during copulation . Often the sex can be determined by the particularities of the location of the setae, especially on the anal segment or by the structural details of the apical part of the elytra, by the features of the microsculpture, etc. In addition to the qualitative features, the males often differ from the females in body proportions. Real and well-defined secondary sexual characteristics , which are well known among other beetles, are relatively rare in ground beetles. The most famous example is the extended segments of the tarsus ( lat. Tarsus ) in male ground beetles of the genus Carabus .

Ground beetle larvae are known to be much worse than adults and are currently the subject of intensive study. Usually they are campodeevoid , more or less sclerotized , less often (in symphilic and parasitoid ground beetles), the larvae are depigmented , and the limbs are greatly shortened. The clypeus is merged with the forehead, its front edge is serrated. Glazkov usually has 6 on each side, less often they are less or not at all. Antennae with 3-5 segments (most often with 4) segments. Legs as in adults with 5 segments. The abdomen is 10-segmented, tergite IX usually with a pair of simple or segmented urogomphs , the structure of which is an important diagnostic feature. The X segment often forms a pusher .

Among all abiotic factors for most ground beetles, soil moisture is the most important. The vast majority of species prefer moist biotopes with relatively low temperatures . Such requirements are especially characteristic of non-specialized predators - polyphages . Among phytophages, the proportion of mesoxerophilic species is much higher, since these species, like other phytophages , are able to compensate for the lack of moisture in the body due to plant tissues. Among parasitoids, there are also a significant number of species resistant to lack of moisture and high temperatures. An extensive group of ground beetles withstands severe salinization and is found along the shores of salt lakes and salt marshes .

The extraordinary ecological plasticity of the members of the family is the reason for the widespread abundance of these beetles. Ground beetles inhabit almost the entire range of latitudes from the cold tundra to deserts and tropical forests ; in the mountains they rise to the subnival belt and in most cases are one of the most characteristic components of adnival ecosystems .

In ground beetles, all the main types of daily activity are known. The boundary between nocturnal and diurnal species is often very uncertain, both due to intrapopulation heterogeneity and seasonal changes in daily activity. It is important to note that oligothermicity , meso - and hygrophilicity of most species of ground beetles are often the key to understanding the peculiarities of ground beetle circadian rhythms . In spring, in conditions of relatively high soil moisture, an abundance of precipitation and low temperatures, many species, usually ranked as nocturnal, lead a daytime lifestyle. So, in the spring in the open landscapes of the steppe zone, purely visual counts allow not only to detect, but even to estimate the number of almost all dominant and subdominant species. In early summer, in the Alpine meadows during the day, you can observe the many active Carabus , Pterostichus , Calathus and Nebria , which later go almost exclusively to a nocturnal lifestyle. Interestingly, this phenomenon is more characteristic of the Carpathians and the humid regions of the Caucasus , while in the drier mountains of Central Asia and the East Caucasus, it occurs only in a limited range of species. As the average daily temperatures increase and the soil dries up, the peak of their activity gradually shifts during twilight, and then at night. Such changes occur quite easily, because at the height of summer, daytime species have a peak of activity in the afternoon, and nighttime species in the first hours after sunset, and thus, to change from one group to another, it is enough to change the peak of activity for only a few hours.

The coincidence of the peak diurnal activity of most species at sunset rather than at sunrise proves that the key adverse factor to which adaptation occurs is moisture deficit rather than high temperatures, since it is due to a decrease in temperature that the relative air humidity increases in the evening clock. In all likelihood, solar insolation may be the most important adverse factor. This is supported by the intense metallic color of a number of daytime and predominantly nocturnal activity of many adnival species . These latter occur high in the mountains near the edge of melting snow fields and are often characterized by depigmentation and thinning of the covers. Such morphological changes are understandable from the point of view of the absence of the need to combat moisture deficit, but they make adnival species very vulnerable to solar radiation and, probably, force them to lead a nocturnal lifestyle in conditions that at first glance seem unsuitable for this. If you go to the edge of the snowfields in the Western Caucasus after sunset, then at a temperature of about 0 degrees, often in an icy wind, you can find many representatives of the genus N. tenella scurrying directly on the surface of the snow, who probe each hole in the snow in search of thawed animals organic residues, recently frozen careless insects, etc. The given example demonstrates a definite relationship between the biotopic specialization of the species and the nature of daily activity. From this point of view, the type of food is also important. Most phytophiles and many drive species are active during the day. On the contrary, among geobionts and mixophytophages, the vast majority of species have nocturnal activity.

Often, due to the nature of the diurnal dynamics, the flight of ground beetles to the light is also considered (Kryzhanovsky, 1983). Flight is most intense in arid landscapes , usually at fairly high night temperatures. Ground beetles flying in the light can be conditionally divided into 2 large groups. One includes species making a resettlement flight , the latter is committed by recently released young bugs, and as it matures, the ability to fly is lost, which may even be accompanied by irreversible resorption of the wing muscles. Such a flight for each species acquires a mass character only once a season . Another group includes species that fly to the light more or less evenly throughout the season. In this case, massive years can be observed several times in one season, provoked by various circumstances (for example, in coastal species - drying up of a reservoir ).

The vast majority of ground beetles belongs to monovoltine species and gives only one generation per year. In the polar regions and at high altitudes, some of these species do not have time to complete development in one season and then the development lasts two years. Wintering beetles are usually of different ages and some of them winter the second time. Some species always develop over one year. Less known are cases where two generations of ground beetles develop over the course of a year. In general, ground beetles are characterized by endogenous diapause . Temperature or photoperiodic reactivation , in the second case, often two-stage, consisting of a mandatory short-day and subsequent long-day phases. In some species, reactivation control is different in males and females . Summer estivation is known for a number of species.

Traditionally, according to the type of seasonal dynamics, ground beetles are divided into 3 main groups: spring adults with autumn activity (overwintered adults reproduce in spring, beetles complete their development in summer , young adults are active in autumn ), spring adults without autumn activity (unlike the previous group, adults do not go out in autumn from a pupal cradle) and autumn species ( larvae overwinter, adults reproduce in the second half of summer and autumn). This separation was proposed on the basis of museum material (Larsson, 1939). Subsequent field studies significantly enriched our understanding of the types of seasonal dynamics of ground beetles, but the division into spring and autumn species has stood the test of time. The most developed system of annual rhythms, taking into account the nature of diapause, was proposed by Thiele (Thiele, 1977). Most often, ground beetles breed in the wettest season - winter in arid countries and the monsoon period in tropical countries. For cave species of ground beetles, annual rhythms are not known.

The overwhelming majority of ground beetles belongs to polyphagous predators , which in combination with a high number largely determines their practical significance. Из-за отсутствия определяющей зависимости от плотности вредителя жужелицы могут остановить нарастание численности вредителя ещё до достижения последним порога вредоносности. Сложность разведения , вероятно, никогда не позволит применять в отношении полезных жужелиц метод наводняющих выпусков , метод сезонной колонизации и пр., но использование щадящих средств защиты растений, продуманного расположения различных культур, правильного севооборота позволяют повысить эффективность этих энтомофагов в рамках интенсивно развиваемой сейчас стратегии рационального землепользования.

Хорошо известны также успешные примеры акклиматизации ряда видов жужелиц (в частности красотелов ) в Северной Америке . Среди жужелиц фитофагов и миксофагов имеются хозяйственно значимые вредители , из которых наиболее известны несколько видов хлебных жужелиц (представители рода Zabrus ).

Объём и границы семейства до сих пор не устоялись и зависят от автора и соответствующей научной школы. Наиболее дробная система принята французскими энтомологами, которые делят жужелиц на почти полсотни самостоятельных семейств, большей частью, соответствующих подсемействам и трибам в понимании других авторов.

Систематический список жужелиц (Carabidae) России содержит 3293 таксонов (5 подсемейств, 40 триб, 184 рода, 289 подродов, 1959 видов и 592 подвида) ^[3] .

Неполный список подсемейств и родов :

• Список жужелиц Армении
• Список жужелиц Белоруссии
• Список жужелиц Эстонии
• Список жужелиц Молдавии
• Список жужелиц Бутана
• Список русских названий жужелиц
• Steropanus infissus
• Amerizus bhutanensis
• Chaetobroscus bhutanensis
• Leptotrachelus

• Крыжановский О. Л. Жуки подотряда Adephaga (семейства Rhysodidae, Trachypachidae, Carabidae) // Фауна СССР. Жесткокрылые, т. 1, вып. 2. Л., изд-во «Наука», 1983. 341 с.
• Arndt, E.; Beutel, RG; Will, KW 7.8. Carabidae Latreille, 1802. // Handbook of Zoology, Vol. IV Arthropoda: Insecta. Part 38: Coleoptera / vol. eds. Beutel, RG and Leschen, RAB — Berlin, New York: Walter De Gruyter, 2005. — Т. 1: Morphology and Systematics (Archostemata, Adephaga, Myxophaga, Polyphaga (partim). — P. 119-146.
• Ground beetles // Brockhaus and Efron Encyclopedic Dictionary : in 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.

• Carabidae of the World Website The world's largest online resource on taxonomy, distribution, and biology of ground beetles .
• Ground beetles (Carabidae) - specialist opinion (www.zin.ru)
• A systematic list of Coleoptera families and subfamilies (Lawrence, Newton, 1995).
• List of beetle families in Russia .
• Simplified classification and Russian names of the families of modern Palearctic beetles .
• List of ground beetles experts (Eng.)
• Born to run - Vasily Trufanov's essay on ground beetles