Silky pill roll

Silky pill roll
	Silky pills ( Gymnopleurus geoffroyi ) on dung ball
Systematics
Class :	Insects (Insecta)
Order :	Beetle (Coleoptera)
Family :	Scarab beetle (Scarabaeidae)
Subfamily :	Scarabaeinae
Genre :	Gymnopleurus
Type :	Silky pill roll
Scientific name
	Gymnopleurus geoffroyi
	( Füssli , 1775)

The Silky pill tome ( Gymnopleurus geoffroyi ) is a beetle from the family of scarab beetles and one of the Koprophagen . The genus Gymnopleurus is represented in Europe with four species .

The beetles do brood care . In a gender-specific collaboration, males and females produce dung balls, which they roll away from the dung heap and bury individually. The dung balls are then thoroughly worked twice underground, creating a breeding pear. One egg is laid in each brood pear.

The beetle is classified as extinct or missing (category 0) in Germany and parts of Austria . He is kept in a list, according to which he is assured of support for protective measures in the event of his rediscovery in Bavaria.

Notes on names and synonyms

As early as 1762, the beetle was described in great detail by Geoffroy under the French name Le bousier à couture (such as the dung beetle with seam ) and assigned to the genus Copris as the eighth species . However, since Geoffroy does not give the animal a two-part Latin name corresponding to the binomial nomenclature , this description is not recognized as the first description. Knowing the description by Geoffroy, Füssli describes the beetle in 1775 under the German name Geoffrois piston beetle and the scientific name Scarabaeus geoffroae . He gives the name an asterisk, indicating a new species. This description is considered the first description. Füssli notes in his description that Geoffroy already refers to the unusual structure of the wing coverts. This peculiarity is also expressed in the name of the genus Gymnopleurus established by Illiger in 1803 . The name is from altgr. γυμνός gymnos for naked and πλευρόν pleuron for side derived. It refers to the fact that the wing covers leave the sides of the first abdominal ring uncovered.

The incorrectly formed genitive for the name Geoffroy at Füssli is now replaced by geoffroyi and explains the species name of the beetle. Panzer writes: “I would very much like to admit that Geoffroyi is spelled more correctly than Geoffroyae. But Messrs. Creutzer and Illiger are very wrong when they claim that it was I who formed or stated this incorrect Geoffroyae. Fuessly, Sulzer, Scriba, Goetze, Harrer - wrote Geoffroyae long before me. ”The author Füssli is usually called Fuessly.

From the German part of the name silky one could infer fine hair. However, there is no such thing, only reference is made to the beetle's matt gloss. The part of the name Pillenwälzer , less aptly also Pill Twist , refers to the transport of the dung ball.

The beetle has been described under numerous synonyms . The synonym Gymnopleurus cantharus is widespread in older literature , for example in Reitter in the Fauna Germanica . The name cantharus was already in use for the pill roll in ancient times. In 1803 Illiger replaced geoffroyi with cantharus with the aim of eliminating contradicting names. However, rather the opposite has been achieved. The early descriptions are usually not precise enough; the names are used in different senses by different authors. Only later is it recognized that males and females have different structures and that it is important whether the freely visible part of the abdomen is keeled or not. Duftschmid separates geoffroyi and cantharus in 1805, counting the males as geoffroyi and the females as cantharus . Also Mulsant leads 1871 geoffroyi and cantharus as different types and writes geoffroyi Sulzer one keeled side of the first abdominal segment to which neither Geoffroy still Füssli mention cantharus contrast, the absence of such keel. The species cantharus , defined in the sense of Erichson and Illiger , has, like geoffryoi Fuessli, no keel, the names are synonyms.

In addition, color variants were named as species, for example cyanescens for bluish beetles.

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Fig. 1: Transporting the dung ball

Fig. 2: Head and rasp-like grain of the pronotum towards the edge	Fig. 3: Underside, legs partially removed, middle hip tinted green

Fig. 4: Detail of the pronotum surface structure	Fig. 5: right front, middle and rear leg from above (♂)

Fig. 6: Section of the side view near the base of the wing cover, colored copy below ; yellow: breast shield; green: wing-coverts, blue: 1st sternite, red-brown: 2nd sternite, white: keel

Fig. 7: Unfolded skin wing with the cover wing closed

Characteristics of the beetle

The broad beetle is only slightly arched. Its length varies between ten and fifteen millimeters, the width is greatest in the second third of the pronotum and varies between 5.6 and nine millimeters. The beetle is only 1.7 times as long as it is wide. The beetle narrows towards the rear. It is dull black and can sometimes show a bluish or greenish hue, but is not shiny like the Gymnopleurus aciculatus native to the Caucasus . The pronotum and elytra are not roughly punctured as in Gymnopleurus flagellatus .

The head (Fig. 2) appears to be armored. It is edged at the back and closes tightly to the pronotum. The mouthparts and the deflection of the antennae are covered up by the head shield. The large, round eyes can only look up through a narrow slit. The head shield is outlined in the middle at the front so that the head ends with a blunt two-pointed tip towards the front. The side of the head shield is set off by a raised seam, towards the rear the two seams approach each other. The forehead is without bumps. The antennae are nine-part. The first link is long and cylindrical, the second short, the third somewhat longer and, conversely, conical, the three following links again short, the last three links form an egg-shaped club covered with a fine felt felt. The three-part lip stylus has a large base part that is enlarged on the inside, the second part is small, both are densely bristled. The distal phalanx is also small, egg-shaped and smooth. The thin, four-part jaw probes have a spindle-shaped end member.

Like the head, the pronotum is dense and finely wrinkled, very finely dotted in the spaces between it (Fig. 4) and, towards the edge, additionally grained like a rasp. At the back the pronotum is edged and closes tightly to the base of the elytra. On each side of the pronotum there is a round dimple (easily recognizable in the taxo image) near the side edge, just behind half the length.

The label is missing.

The elytra are also fine-grained, but somewhat coarser than the pronotum. They are shorter than the head and pronotum combined. Laterally, the wing covers are only slightly drawn down. They are wide and deep behind the shoulders so that the side of the first abdomen sternite and the approaches of the neighboring sternite are visible from above . This section enables the insect to fly with the wing covers closed (Fig. 7). Viewed from the side, a clear keel can be seen within the cutout on the side of the second sternite. Unlike Gymnopleurus sturmi and Gymnopleurus mopsi, this does not have a continuation on the first sternite. The side of the first sternite is slightly arched, but without a keel (Fig. 6).

The legs are designed very differently (Fig. 5). The front legs are typical grave legs. Not only the front rails, but also the front legs are widened. They have a tooth on the rear edge (i.e. in front) that is stronger in the male than in the female. The tarsi of the forelegs are only weakly developed, the splints have three strong external teeth. At its end there is a strong thorn that is blunt and straight in the male and slightly curved and pointed in the female. However, as the tips become increasingly worn as a result of digging, this feature is not reliable in adult animals. On the other hand, a certain characteristic is that the inside of the front splint is notched across the entire length of the males, whereas in the females it is only in the adjacent part.

The other legs also have a pin at the end of the rail. The legs of the rear pair of legs are significantly longer than those of the middle pair of legs, especially the curved rails. These only have one end mandrel. They allow the dung ball to be compressed efficiently, which makes it easier to transport. The claw link on all legs is longer than the four other tarsal links together.

The middle hips are clearly slanted and far apart, but less than in the genus Sisyphus (Fig. 3), the front and rear hips are closer together.

biology

Biotope and activity

The beetle can be found on warm and dry pastures. As heat-loving animals, the beetles in Central Europe only end their winter dormancy when temperatures reach high values in mid-May. The animals of the new generation appear in late July to late August. In autumn the animals can be observed until October. On cooler days, they only leave the protective area of the ground in the warm midday hours, in midsummer, on the other hand, they are already active in the morning hours and even at dusk. When the weather is unfavorable, the acquisition of food and activities related to reproduction are almost stopped. The beetles stop their activities when it rains lightly, and dig in when it rains heavily. In warm and dry weather between 20 and 26 ° C, the beetles are agile and happy to fly. When flying, the deck wings remain closed (Fig. 7). Even the shadow of a cloud slows down activities considerably.

Both sexes need a post-hatch maturation feeding . This extends over the entire summer in the year of birth and continues next spring after wintering. The manufacture of fecal balls for personal consumption, as is observed in some other coprophages, has not been found in Gymnopleurus geoffroyi . They only make brood pills intended for the offspring. However, these can be used as a source of food by strangers if they are orphaned. Disputes between bugs are rarely observed.

The beetle prefers cow dung for ingestion, but is also often found on sheep droppings, less often in horse droppings. During feeding attempts, the species also accepts the droppings of other herbivores, in particular the zebu , but also goats and red deer and, in an emergency, also elephants and rabbits. The excrements of omnivores (humans, pigs) are attractive, but are not eaten with pleasure. The beetle only eats on the dung heap above ground.

As a rule, only the types of faeces that are eaten with pleasure are also used to build brood pills as feed stock for the offspring, so the faeces of goats, humans and pigs, elephants and rabbits were not used to build brood pills.

The beetles fly around with their antennae stretched out and the antennae lamellae spread out in search of food. If the dung is perceived olfactory , the beetle lands immediately. Running beetles stop from time to time, keep their abdomen lowered and their heads raised, and turn them back and forth with their antennae outstretched. If they do not find any fragrances, they continue in the same direction. Otherwise they turn abruptly in the direction of the fragrance source and begin to run towards it at increasing speed. Shortly before this, perception begins through the maxillary buttons, which are moved lively. Once at the food source, it is checked with lip and jaw sensors before the eating process begins.

Hungry bugs can eat large amounts of manure. One female was measured to ingest 190% of her initial body weight in food. The beetles hardly pause during the feeding process, at most to clean the mouthparts. After just a short period of eating, the beetle excretes a black-brown, shiny strand that is getting longer and longer. This consists of short, closely spaced, cylindrical parts of two to three millimeters in length, which are created by the dropping of the manure in short intervals.

Brood care refers to the protection of eggs, larvae and pupae and to the provision of larval food. However, the larvae are not fed. Both males and females can judge whether the manure found is suitable for the production of breeding pills, they can produce and move breeding pills. However, after some time, the males without females leave their brood pills, run back to the dung heap and possibly make a new ball. The females without males, however, also bury the brood pills and cover them with eggs. Usually, however, a male and a female work together.

The reproductive biology of the beetle was examined very carefully by Prasse. The following information relates to four of his publications.

The development cycle is one year, the average lifespan of the adults at Prasse was 345 days. The females die eight to ten days before the males. The aging of the beetles becomes noticeable through the decrease in irritability and readiness to fly. Food intake is decreasing and attempts to escape are increasingly neglected. Finally, body cleansing is neglected. Often, mites settle in large colonies, mainly on the ventral side of the chest section. Largely weakened animals can no longer find the strength to dig themselves into the ground and die in the evening. It is not uncommon for individual leg links to be lost.

Copulation

Only after the gonads have matured do the sexes take notice of each other. Males and females find each other on the food substrate and begin to take care of the brood together. The sexes recognize each other chemotactically . If a partner of the opposite sex comes across a male or female who is found without a partner in possession of a pill, the two of them make brief contact with their heads and splayed feeler blades, then they move the pill on together. The male recognizes a female from a distance of several centimeters, whereas the female only reacts to the male in the immediate vicinity. Mating takes place above ground on the substrate, underground in the ground or on the brood pill. A minimum temperature of 18 ° C is required.

The male climbs from behind or from the side of the female, stroking her front legs over her pronotum and the wing covers. If the female is not willing to mate, the male strips it off with its hind legs and the middle pair of legs; the male tries to change the mind of the female by further stroking. If the female allows it, the male clings to the base of the wing cover with the front tarsi and slides back over the end of the body and rests on the third pair of legs. The penis is stretched out and a semen packet is inserted into the female. Copulation takes twenty to forty minutes. The size of the beetles does not matter, animals of the same size mate, or the male or female is larger than the partner. During the breeding season, the females are mated several times, probably by different males outdoors.

Before the first oviposition, copulations sometimes take place several times in a row, later they only take place occasionally. The egg-laying period extends over several weeks, in Central Europe from the end of May.

Production of the brood pill

Fig. 8: Sheep droppings

Fig. 9: Cattle droppings

Sheep excrement consists of excrement beans more or less stuck together (Fig. 8). The beetle chooses a bean as the starting point for its ball. If this is too big, parts of the bean with the head shield are peeled off. If it is too small, parts of other beans are cut off with the front rails and pressed against the selected bean. The beetle does not leave its ball, but pushes it towards other manure beans if there is no manure within range of the front legs.

With cow dung (Fig. 9), the female usually begins to build a ball by first pressing the front legs into suitable manure and then pulling it against the body, thereby compressing the manure. The legs work alternately and repeatedly until there is a portion of compressed dung on the chest and a five to six millimeter hole is created at the same time. Now the female begins to work, slowly turning. The male now works next to the female and turns in the opposite sense than the female. This creates a ring-shaped ditch that encloses a compressed, arched manure mass. Now the two animals work their way diagonally downwards under this mass, thereby deepening the trench and the enclosed piece increasingly takes on a spherical shape. The beetles interrupt their digging work at irregular intervals and knead and press the resulting ball, peel off further dung disks from the outer edge of the ring ditch and press them against the dung ball. Finally, a beetle squeezes under the ball, separates it from the manure underneath and lifts it up a little. The underside of the sphere is now correspondingly smoothed and rounded from below. Then the top is also smoothed and rounded again and the finished ball pried out of the hole and rolled away.

In the case of piles of dung that has already become encrusted through drying, the brood pill can also be made from the side or even from below.

It takes about ten to forty minutes to make a brood pill. The cooperation of a couple shortens the production time by about a third. The diameter of a finished pill is about 18 millimeters and depends on the size of the beetles that make the pill. Pills made by a couple together are no bigger than those made by just one animal. If there is a lack of suitable manure, the pills can be smaller.

Transport of the brood pill

For transport, the male stands on his hind legs, grabs the ball with his front legs and pulls the ball towards him (Fig. 1 right). It steps backwards. The female positions herself on the opposite side of the pill with the end of her body facing the ball. It stands with the rails of the forelegs on the ground with the forelegs angled. The other two pairs of legs hold the ball or push it backwards. The animal has to catch up with its front legs. So the female also moves backwards. Usually the male pulls and the female pushes. A female transporting alone pushes the ball, a male working alone pulls it.

The posture adopted by the male at the beginning determines the direction of the transport, which is generally persistently maintained. Obstacles are not bypassed, but overcome. Prasse reports on a case in which a male came across a vertical wooden slat. He managed to climb it up to a height of nine inches, which took him twelve minutes. He found support for the hind legs in a drying crack in the wood and dragged the ball along with the helplessly hanging female with the two pairs of front legs. When the ball and the beetles clinging to it roll back in an uncontrolled manner, the starting position and the direction of transport usually change in similar cases, so that the next attempt at the obstacle is crowned with success at the latest after several attempts. In one case, it was observed that after a thirty minute unsuccessful attempt to overcome an obstacle, the bullet was buried in front of the obstacle. In addition, the direction of transport can also take place suddenly through the change of position of the male or through the shape of an obstacle.

Occasionally, transport damage is repaired en route, but the pill is neither actively provided with an earth's mantle to prevent it from drying out, nor is it additionally compressed. Of course, rolling can cause a layer of dust to form on the damp surface of the ball. If there is the possibility of food ingestion on the way, this is occasionally used by the beetles, but the brood pill is never misused to ingest food.

Burying the brood pill

The transport of the brood pill is suddenly interrupted and the female digs herself head first under the ball. Then it pushes the earth under the ball upwards laterally with its head and pronotum, repeating this process several times with a different starting position. This creates an earth wall around the sphere and the sphere sinks downwards. If the ball gets stuck in the resulting shaft, the female grabs it with the front pairs of legs and pulls it downwards. If this is unsuccessful, she grabs the ball with all three pairs of legs and turns it into the shaft. The male sits on top of the ball the whole time and can be buried with it. On average, it takes ten to fifteen minutes to bury, no more than 25 minutes. Cases have also been observed where the digging was aborted unsuccessfully and a new digging attempt was started a short distance away from the unsuccessful attempt.

After the breeding pill has sunk into the ground, the female begins to drive the shaft vertically or slightly obliquely downwards, with a diameter that is larger than the diameter of the sphere. The resulting soil is pushed out past the ball. The male waiting on the ball then pushes this material upwards. This closes the shaft above the sphere and the ring-shaped earth wall is piled up into a small hill. The shaft above the sphere is filled from top to bottom with further earth masses. As a rule, the work on extending the shaft ends when it turns into an approximately horizontal four to six centimeter long corridor that ends blindly and in which the ball comes to rest. Now the female begins to dig up the earth around the dung ball that has sunk down, the male pushes the accumulating material up into the shaft. This creates a cave with smooth walls and a level floor, the so-called brood chamber, in the middle of which the brood pill is located. The size of the chamber, 21 to 33 millimeters in height and 22 to 38 millimeters in width and length, allows the female to move freely on all sides of the brood pill. The depth of the chamber in the breeding cage with a floor layer of eight inches was six to eight inches. In nature, the breeding caves are likely to be deeper, because shafts were found that were twenty centimeters deep filled with excavated material. On the other hand, it is assumed that in the case of impenetrable obstacles such as large stones, the breeding caves are also less deep.

The creation of the breeding cave is completed in about four to eight hours. If the female works alone, the working hours are extended by around a quarter to a third. After completion of the breeding cave and possibly another copulation, the male will probably leave the female of its own accord and digs to the surface of the earth.

Egg laying and brood pear

The female now transforms the brood pill into the brood pear. This takes place in two steps, the so-called re-baking and the actual production of the breeding pear. The female climbs the dung ball and works her way down into the ball with the help of her head and forelegs. She takes manure from the middle of the ball and compresses it on her stomach and begins to form a new ball from it. The more the new ball grows, the more the work disintegrates the old pill. Your individual parts are grasped with the front legs and added to the new ball. This process, known as baking, takes forty to fifty minutes. The product is much denser, has a rubbery consistency and has a long shelf life. It is assumed that any contaminants that have been brought in, such as the stages of flies or worms, are also destroyed.

The female now climbs onto the baked ball, opens it from above and takes a portion of feces from the middle, which she places next to the opening that has been created. The female repeats this process many times, moving in a circle around the opening in steps of two to three millimeters. As a result, the deposited manure forms a ring wall around the opening and a chamber is created in the center of the ball. The beetle now bends over the ring wall and smooths and solidifies the walls by tapping and brushing with its front legs. This preparation of the egg chamber takes about one and a half to two hours.

Now the female sits down on the ring wall so that the end of the body comes to rest over the opening. A single egg is deposited in this opening. Now the ring wall is pressed inwards, whereby the pill is once again circled. After that the opening is almost closed. As the ring wall and the underlying parts are further removed and the material accumulated over the center of the opening, the pill takes on a pear-shaped shape. This brood pear is now evenly coated with soil, which the female takes from the bottom of the brood chamber. The time required for this was measured in two cases. It was three hours and four hours. The female then leaves the brood chamber for good.

The breeding pears are on average 19.7 millimeters long, 16.7 millimeters wide and 3.18 grams in weight (average of 110 objects). In the Prasse cattery, a female produced an average of five breeding pears during the breeding period. Probably the number is a bit higher in the wild.

Embryonic development

The freshly laid eggs are egg-shaped, yellowish and shiny, soft, smooth and moist. In the following days the eggs lose their shine and finally become matt. The elasticity of the egg and the egg membrane increase. As a rule, the wide end of the egg sits on the bottom of the egg chamber, the tip leans against the wall of the egg chamber and sticks there slightly. The egg size fluctuates considerably, on average the egg is 5.8 millimeters long and 3.4 millimeters wide, i.e. 1.7 times as long as it is wide. It weighs an average of 41 milligrams. The eggs are therefore unusually large and rich in yolks. Towards the end of the laying period, the eggs are slightly smaller.

During embryonic development, the egg increases in length by about 0.7 millimeters and in width by 1.1 millimeters. The future mandibles can be recognized by three-day-old eggs as two closely spaced dark spots at the tip of the egg. From the 5th day onwards you can see a stripe that reflects the future segmentation of the larva. One to two days before hatching you can see the position of the larva, the head is at the narrow end of the egg, the abdomen is wrapped up to the chest and fills the thick end of the egg. In the Prasse cattery it took the eggs eight to nine days at a temperature of 18 to 20 ° C and five to seven days for the larva to hatch at a temperature of 24 to 25 ° C.

Larval stages

The species forms three larval stages. The first stage is on average 6.8 millimeters long and 3.0 millimeters wide with a head capsule width of 2.25 millimeters. The second stage is on average 12.1 millimeters long with a width of 5.5 millimeters and a head capsule width of 2.68 millimeters. In the third stage, the corresponding values are 18.2 millimeters for the length of the larva, 8.3 millimeters for its width and 3.15 millimeters for the width of the head capsule.

The young larvae do not have an organ to rupture the egg membrane; they presumably insert their mandibles. After hatching, the larva remains calm for 24 to 48 hours, digesting the remaining yolk trapped in the intestine. Then she begins to eat. Except for brief interruptions, this takes place non-stop. The first larva will most likely also eat the remains of the egg, but mainly it will enlarge the egg chamber by consuming the manure on its walls. The hump-like bulge of the larva in the second to fifth abdominal segment only develops after a few days and is caused by the loops of the middle and rectum in this area. While the egg chamber walls are initially eaten on all sides, after entering the second stage, the egg chamber is widened from the center mainly downwards. Experiments show that the larva is guided by gravity. In this direction most of the food supply is available without running the risk of breaking through the walls of the breeding pear.

Changes in the position of the larva are made by pressing two of each of the three body areas, head with legs, hump and abdominal plate, against the wall, and the third changing its position. This is only successful if the wall is everywhere the same distance from the center, i.e. the chamber forms a sphere, and if the sphere diameter does not grow faster than the larva. This is only possible because the larva distributes its excrement, pulpy balls, on the walls in such a way that the spherical shape is retained. As a result, it cannot be avoided that the larva also ingests its own excrement together with the material of the breeding pear. However, this is nothing special in animals with plant food, as it enables optimal digestion of the food. The larva’s free mobility enables it to close cracks and holes in the breeding pear with its excrement.

The moults are done by first opening the head capsule and tearing open the old larval skin in the direction of the back when the new head capsule emerges. Before moulting, food intake is stopped, after moulting there is a rest phase to harden the chitin . In Gymnopleurus geoffroyi, the interruption of food intake per molt takes a total of about 36 hours. As with the first larval stage, food intake takes place almost without interruption in between.

During the third stage, the larva attaches fat under the skin. The color changes from gray-white to yellow-white and the body swells a lot. About four days before the larval development ends, the larva stops eating and completely empties the intestines. The contents of the intestine are spread on the wall of the dwelling cavity. The larva decays into the almost immobile state that precedes pupation. The total time of the stages to pupation was 26 to 28 days at 18 to 20 ° C and 23 to 24 days at 24 to 25 ° C.

Doll

The moulting to the pupa is initiated by the previously lethargic larva, alternately bending and stretching. The seams of the head capsule and the seams along the chest section burst. The entire front of the doll is exposed. Rotating movements to the side and beating movements of the abdomen cause the skin to be sloughed backwards. In a glass tube, this process took about an hour and a half. The doll lies on its back, on the floor of the doll's chamber, protected from direct contact with the ground by bulges on all three breast sections and all abdomen sections. It is unusually irritable. The pupal stage lasts sixteen to eighteen days at 18 to 20 ° C and 13 to 14 days at 24 to 25 ° C. The doll is on average 13.15 millimeters long and 10.02 millimeters wide. The contours of the finished insect are clearly visible.

The moulting is initiated again by stretching movements, which in this case first tear the doll's skin on the legs, then the skin on the rear edge of the head and the chest section. The young beetle slowly pushes itself forward out of the shell, at the same time its hind legs strip the old skin backwards. The elytra immediately assume their final position, the hind wings remain stretched for a long time before they fold under the elytra. The hatching process itself takes about seven to ten hours. The beetle then rests for about five to eight days.

The beetle breaks through the wall of the breeding pear at its weakest point, usually the ground. Then he works his way through the earth to the surface. Only there does he eat food for the first time. In the experiment, young beetles take fresh manure as food before they have hardened and left the breeding chamber.

Fight between the bugs

In contrast to other coprophage beetles, the animals' lust for conflict is rather low. Disputes are limited to the reproductive period. Fights are always expressed in the form of one-on-one fights, either a male fights a male or a female fights a female. It could not be observed that in couples one partner stands by to help the other. Usually the animals pass each other carelessly during the reproductive period. Only when a beetle or a couple is busy manufacturing, transporting or digging in a breeding pill can the fact that a strange beetle gets too close to the pill lead to it being pushed back by the owner of the same sex. Both the attacker and the defender can be put to flight.

Regardless of whether the defender or the attacker takes the place at the ball after the battle, it will be accepted by the partner of the opposite sex. For example, when a brood pill was being buried at an advanced stage, a foreign female approached. The little man sitting on the pill allowed the other person to take part in the digging. Only after some time was the strange female recognized by the other in the ground and a dispute arose. The weaker female was driven away, the other continued its work of digging.

When fighting males against males, three different types of fighting could be observed. When the defending male fights from an elevated position, for example on the ball of feces, it grabs the approaching male from above and hurls it away. The intruder can give up or attack again. If the males are at the same height, they stand up on their hind legs and brace chest against chest against one another. Everyone tries to get their front legs under the opponent's chest and then knock the opponent over backwards by jerking the front legs up. For his part, the opponent tries to let the opponent's blow go into the void by opening the front legs and now to get his front legs under the opponent's chest in order to be able to knock him over. A male is usually successful in these reciprocal attacks. Occasionally the opponents get caught with their front legs and then try to push the opponent away with the head shield until one of them falls over backwards. As a rule, the bigger fighter wins, is recognized as the winner by the Beetle below, and the loser withdraws.

distribution

The species is found from southern France eastwards in southern Europe and the eastern Mediterranean including Asia Minor and North Africa, but is absent in Spain and Portugal. To the north, the species only penetrates into southern Central Europe, there are only old finds from Germany. To the east, however, the beetle penetrates into Iran.

literature

Heinz joy , Karl Wilhelm Harde , Gustav Adolf Lohse (ed.): The beetles of Central Europe . tape 8 . Teredilia Heteromera Lamellicornia . Elsevier, Spektrum, Akademischer Verlag, Munich 1969, ISBN 3-8274-0682-X , p. 281 .
Klaus Koch : The Beetles of Central Europe Ecology . 1st edition. tape 2 . Goecke & Evers, Krefeld 1989, ISBN 3-87263-040-7 , pp. 352 .
Jaques Baraud: Faune de France, Coléoptères Scarabaeoidea d'Europe. Paris 1992.
Edmund Reitter : Fauna Germanica, the beetles of the German Empire. Volume II, KG Lutz 'Verlag, Stuttgart 1909, p. 324 (as Gymnopleurus cantharus ).
Gustav Jäger (Ed.): CG Calwer’s Käferbuch. 3. Edition. K. Thienemanns, Stuttgart 1876, p. 302.

Individual evidence

↑ ^a ^b Systematics and distribution of the species Gymnopleurus geoffroyi in Fauna Europaea, accessed on March 15, 2017

↑ Binot et al .: Red List of Endangered Animals in Germany 1998, Register [1]

↑ Wolfgang Paill, Christian Mairhuber: Checklist and Red List of the scarab beetles and stag beetles in Carinthia with special consideration of the protected species (Coleoptera: Trogidae, Geotrupidae, Scarabaeidae, Lucanidae). In: Carinthia II. 196/116. Year, Klagenfurt 2006, pp. 611–626 ( PDF on ZOBODAT ).

↑ Funding concept of the Bavarian Nature Conservation Fund [2]

↑ ^a ^b Geoffroy (the author is only mentioned in the 2nd edition 1764): Histoire abregée des insectes que se trouvent environ de Paris 1st volume Paris 1762 p. 125: 91, as Copris No. 8

^ Johann Caspar Füßlin: Directory of the Swiss insects known to him ... Zurich and Winterthur 1775, page 2, no. 14

↑ Sigmund Schenkling: Explanation of the scientific beetle names (genus)

^ ^A ^b Johann Karl Wilhelm Illiger (Ed.): Magazine for Insectology. 2nd volume, Braunschweig 1803 p. 201

↑ Georg Wolfgang Franz Panzer: Critical revision of the insect fauna of Germany ... I. Baendchen, Nuremberg 1805 p. 10 above

↑ Kaspar Duftschmid: Fauna Austriae or description of the Austrian insects ... 1. Part Linz and Leipzig 1805 p.161 f.

↑ ^a ^b E. Mulsant, Cl. Rey: Histoire naturelle des coléoptères de France Paris 1871 p. 61

↑ Identification key for Scarabaeidae

↑ WF Erichson: Natural history of the insects of Germany 1st division Coleoptera Berlin 1845 Volume 3, Part 1 p. 754 ff, p. 757 as Gymnopleurus cantharus

↑ Joachim Prasse: "Food acquisition coprophagous Pillenwälzer ( Sisyphus schaefferi L. and Gymnopleurus geoffroyi Fuessl. Col. Scarab.)" In the scientific journal of the Martin Luther University Halle-Wittenberg Math.-Nat. VI / 3, pp. 439-444 June 1957

↑ ^a ^b ^c ^d ^e ^f ^g Joachim Prasse: "The brood care behavior of the Pill Rollers Sisyphus schaefferi L. and Gymnopleurus geoffroyi Fuessl. (Col. Scarab.)" In the scientific journal of the Martin Luther University Halle-Wittenberg Math.-Nat. VI / 4, pp. 589-614 July 1957

↑ ^a ^b ^c Joachim Prasse: "The development of the pills Sisyphus schaefferi L. and Gymnopleurus geoffroyi Fuessl. (Col. Scarab.) In the brood pear" in the scientific journal of the Martin Luther University Halle-Wittenberg Math.-Nat. VI / 6, pp. 1033-1044 December 1957

↑ Joachim Prasse: "The struggles of the pill roll Sisyphus schaefferi L. and Gymnopleurus geoffroyi Fuessl. (Col. Scarab.)" In the scientific journal of the Martin Luther University Halle-Wittenberg Math.-Nat. VII / 1, pp. 89-92 March 1958

Web links

Commons : Silky Pill Roll ( Gymnopleurus geoffroyi ) - Collection of images, videos and audio files

[FEgeof-1] Systematics and distribution of the species Gymnopleurus geoffroyi in Fauna Europaea, accessed on March 15, 2017

[RL-2] Binot et al .: Red List of Endangered Animals in Germany 1998, Register [1]