Ribbed death friend
| Ribbed death friend | ||||||||||||
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Ribbed friend of the dead ( Thanatophilus sinuatus ) on mole carcasses |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Thanatophilus sinuatus | ||||||||||||
| ( Fabricius , 1775) |
The ribbed friend of the dead ( Thanatophilus sinuatus ) is a beetle from the carrion beetle family . The scientific generic name Thanatophilus should be translated as "friend of death" and can be explained by the fact that the beetle is found on carrion. Sinuatus means "curved, curved" and refers to the course of the ribs on the wing-coverts , of which the outer ones are not straight, but slightly curved. The nine to twelve millimeter beetle is widespread and common in Central Europe.
Body features
The black body is flat (Fig. 4) and has an oval outline (Fig. 1). The head and pronotum, the underside of the body and the base of the elytra are hairy whitish to light golden yellow.
The head is about as long as it is wide at eye level. It points forward, behind the short temples, which are enlarged like a cheek, it is constricted with a distinctive furrow. The eleven-link antennae are positioned above the upper jaw, the second link is shorter than the third (Fig. 3). The constriction of the head and the length of the second antennae distinguish the genus Thanatophilus from the similar genus Blithophagus . The last links of the antennae form a club, the last three are enlarged and matt, but not set off like a button nor colored brown. The mouthparts point forward. The upper lip is cut short and deep. The upper jaws are curved at the tip, toothless and fringed on the inner edge. The lower jaws are two-part and fringed. The jaws are four-limbed, the last limb is elongated, walnut and blunt. The lip buttons are tripartite, the end link ovoid.
The pronotum is rounded in a semicircle and cut out behind the head. Numerous flat, bulging elevations on the pane create the visual impression of a surface that has been treated with many hammer blows, similar to a hammered finish . The rear edge of the pronotum protrudes over the base of the elytra.
The wing covers have three sharp longitudinal ribs and a transverse bulge in the last third. The spaces between the ribs are matt throughout. The anterior outer corners of the wing covers (shoulders) are not rounded, as in Thanatophilus dispar , but drawn out into a protruding tooth that is hidden under the pronotum (Fig. 5, colored yellow on the left). In the male, the rear edge of the elytra is more or less rounded or truncated, in the female it is cut out between the inner and middle ribs, the space between the seams is lobed towards the wing- cover seam and the bulge is angled towards the outside (Fig. 1). The wing covers do not completely cover the abdomen. Except for a few spots at the base of the elytra, they are bare. The tag is triangular, large and partially longer with light golden yellow hair.
Six abdominal plates ( abdominal sternite , Fig. 2) are visible on the underside of the body . The penultimate sternite is broadly arched in the female. The middle hips are broadly separated. The back hips are touching. The front hips are brought closer to one another and directed downwards in the shape of a cone. The tarsi are all five-limbed, the first four limbs of the front tarsi are slightly expanded in the male. All rails are densely thorn on the outside.
| Illustrations of Thanatophilus sinuatus | ||
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| Fig. 1: female | Fig. 2: underside | |
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| Fig. 3: From the front | Fig. 4: side view | |
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Fig. 5: Shoulder (front outer corner of the wing cover) from below Copy on the left partially colored: |
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larva
The larvae of the ribbed friend of the dead are isle-shaped, but less flat, but more roundish maggot-shaped. The three breast segments are not significantly different from the ten abdominal segments. A well-developed pair of legs sits on each breast segment, which enables the larvae to move quickly. The larvae of Th. Sinuatus occupy an intermediate position between the even more rounded larvae of Th. Rugosus and the more assel-shaped larvae of Th. Dispar . The long paired appendages of the anal segment (pseudocerci) are two-part. They arise on both sides of the intersegmental skin between the ninth and tenth abdominal segments. The basal phalanx already reaches or protrudes beyond the rear edge of the anal segment, and overall the pseudocerias protrude more than twice as much as the anal segment. The middle parts of the back plates (protergite) are slightly narrower than the segments and therefore do not overlap. The wing-shaped lateral appendages of the tergites (paratergites) are only missing on the prothorax; in the abdominal segments, they end in tips that are drawn backwards. They take up at least two thirds of the width of a segment. The antennas are tripartite. They are brought closer to each other and arise at the front edge of the head. A field of four ocelles lies above and below each antenna root . The forehead has delicate and weak bristles, the bristles are a little lighter than the matt black head capsule. On the upper side, the larva is smooth with only very fine hairs, which are only somewhat thicker and longer on the rear edge of the tergites.
The upper jaws are pointed and without teeth on the inside.
The species has three larval stages. The first larval stage is 5.8 mm long on average, the second measures 9.7 mm and the third 13.3 mm. However, particularly small specimens of the third stage can be smaller than well developed specimens of the second stage. The other body dimensions only change to a limited extent. The shape of the head is particularly interesting. Length to width of the head changes from 0.39 in the first larval instar to 0.74 in the second to 0.58 in the last larval instar. In this case, the head is about twice as wide as it is long. In the first larval stage, on the other hand, it is relatively shorter and often appears even shorter because the head is usually carried lowered. In the second stage, however, the head is relatively longer. Furthermore, in the first larval stage, the body width hardly decreases towards the rear, while the third tapers conically towards the rear, while the second larval stage occupies a central position. In addition, in the first and second larval stage, the second and third antenna segment are of the same length, while the basal segment is significantly shorter. In the third larval stage only, the limbs are about the same length.
Doll
The doll of the ribbed friend of the dead is on average eleven millimeters long and a little over five millimeters wide. It belongs to the type of free pupae in which the extremities and mouthparts are no longer in contact with the body, but the shape of the future beetle can already be recognized.
egg
The eggs are yellowish white and have a matt sheen. As they develop, they grow in size and change color to a milky white. Young eggs measure an average of 1.9 mm × 1.1 mm (length to width), while older eggs measure an average of 2.1 mm × 1.35 mm. The time it takes for the embryo to develop before the larvae hatch is highly temperature-dependent and usually lasts three days.
biology
The beetles are diurnal. Traps are accepted in the evening in spring and in the afternoon in summer. The adult animals fly to find carrion with the help of their sense of smell. They land on or near it and then reach it continuously. Overall, however, the species is not very eager to fly and tends to escape by crawling underground.
There is tough intra- and intra-specific competition for the carrion. Interspecific competition is countered by the way in which it is not selective in terms of both the degree of decomposition and the exposure of the carrion. Ears are accepted from vertebrates (mammals, birds, reptiles) and also from invertebrates . Larger carcasses are used by many individuals of the species at the same time. However, a distinction is made between the animal species from which the carcass originates. For example, baits made from pork are much preferred over those made from dogs or cats.
Copulations are particularly common in spring and early summer. The males hold on to the antennae of the females and often ride for hours. The sperm transfer takes place in spermatophores . When the female is then mated by another male, the male can remove the predecessor's spermatophore with the help of his prickly aedoeagus . The female lays several eggs in a few centimeters deep cave that was dug for this purpose. The eggs rest at the bottom of the cave. The following figures were obtained in the breeding experiment: A female lays an average of more than 40 clutches, an average of almost eleven eggs were laid per clutch, a total of between 400 and 500 eggs.
In captivity, Thantatophilus sinuatus can produce up to four generations per year, but usually fewer. In the experiment, the development from egg to hatching of the beetle took about 62 days for the first generation and 48 days for the second generation. While the first two generations could be bred without any effort, the breeding success in the following generations was significantly worse. It is therefore assumed that only two generations occur in nature. In the experiment, most of the hibernating beetles came from the second generation, none from the first generation and only very few from later generations. At least in Central Europe, the beetle probably has two generations per year.
Larvae and adults are strictly necrophagous . Live earthworms, insect larvae and even weaker conspecifics are only attacked in great need (in the test container). The food is kneaded with the mandibles and mixed with vomited digestive juice from the midgut. In this way, some of the food is digested outside of the intestine (extratestinally). Larvae and adults can eat large amounts of food and, on the other hand, show amazing hunger skills. However, an oversupply or lack of food has little effect on the development time of the larvae. Only in the third and last larval stage do fluctuations appear, which are not due to the temperature but to the food supply. However, they relate to the percentage distribution of resting and feeding times, not to the total duration of the larval stage. The first larval stage lasts just under three days, the second larval stage a good two days and the third larval stage a little over ten days. The third instar larva digs into the ground and creates a cavity by hitting the abdomen, in which pupation then takes place. The pupa takes about ten days to hatch. The young beetle changes color in ten to thirty hours depending on the light conditions and usually leaves the pupa’s cave after two days. It begins immediately with the ripening process , which lasts almost two weeks.
In the experiment, the beetles buried themselves up to six inches deep into the ground for wintering. This was only done by individuals who had not yet begun to reproduce. Beetles that had already reproduced ran around well into autumn and gradually died.
According to other information, a clutch consists of an average of 5 eggs and the eggs have an average volume of 0.21 mm³. According to another source, the development from egg-laying to hatching of the beetle takes 24 days at 20 ° C. These differences may be due to the fact that a different subspecies was used.
Use in forensics
The full-grown beetle can be found on fresh carrion , at all stages of putrefaction down to dry bones. Whether the carcass is exposed to the sun or in the shade is relatively unimportant, only at temperatures above 30 ° C you see the beetles less often. The species can therefore only be used to a very limited extent in forensics to narrow down the possible time of death of a corpse or to provide information about where it was previously. On the other hand, conclusions about the cause of death can possibly be drawn from Thanatophilus sinuatus . In laboratory tests there was a good correlation between the morphine content of the carcass and the morphine content in the second and third larval instar of the beetle. Poisons could therefore still be quantitatively detected in the beetle , while this may no longer be possible on the carcass.
Occurrence
The species is widespread in the Palearctic . Except in Europe, North Asia and North Africa they are found in Japan and Korea, there in the subspecies Th. S. auripilosus .
The beetle occurs all year round in the Mediterranean region. There the beetle is found more frequently in wooded areas than in open land. For Central Europe, open-land biotopes are given as preferred habitats.
Individual evidence
- ↑ Petr Kočárek: Diel activity patterns of carrion-visiting Coleoptera studied by time-sorting pitfall traps. In: Biologia, Bratislava. 57/2, 2002, pp. 199-211. doi: 10.1076 / brhm.32.4.431.1333 osu.cz (PDF).
- ↑ Bernhard Schnepf: Investigations on the carrion-dwelling beetle fauna of Erlangen. Admission work. Institute for Biology, Friedrich-Alexander-Universität Nürnberg-Erlangen February 2007 as PDF ( Memento from October 20, 2007 in the Internet Archive )
- ↑ C. Neuner, K. Peschke: Removal of spermatophores in successive copulations of Thanatophilus sinuatus (Silphidae). In: Negotiations of the German Zoological Society. Short publications. 87, 1994, p. 97.
- ↑ a b H. Ikeda, T. Kagaya, K. Kubota, T. Abe: Evolutionary relationships among food habit, loss of flight, and reproductive traits: life-history evolution in the Silphinae (Coleoptera: Silphidae). ( Memento of February 5, 2015 in the Internet Archive ) In: Evolution; international journal of organic evolution. Volume 62, Number 8, August 2008, ISSN 0014-3820 , pp. 2065-2079. doi: 10.1111 / j.1558-5646.2008.00432.x . PMID 18507741 .
- ↑ Jae C. Choe, Bernard J. Crespi (Eds.): The Evolution of Social Behavior in Insects and Arachnids. Cambridge University Press, 1997, ISBN 0-521-58977-0 , p. 222.
- ↑ M. Castillo-Miralbés: Principales especies de coleópteros necrófagos en carroña de cerdos en la comarca de la litera (HUESCA). In: Graellsia. 57 (1), 2001, pp. 85-90. (PDF) ( Memento of July 6, 2012 in the Internet Archive )
- ↑ José Luis Romero Palanco, Francisco Munguía Girón, Joaquín Gamero Lucas: Entomología cadavérica en la provincia de Cádiz (S. de España). In: Ciencia Forense. 8/2006, pp. 83-106. dpz.es (PDF).
- ↑ Morphine content in carcasses and beetle larvae
- ^ W. Schawaller: Taxonomy and Faunistics of the genus Thanatophilus. In: Stuttgart contributions to natural history. Ser. A, No. 351, Stuttgart, December 1, 1981.
literature
- Heinz Joy, Karl Wilhelm Harde, Gustav Adolf Lohse: The beetles of Central Europe . tape 3 . Adephaga 2 - Staphylinoidea 1. Goecke & Evers, Krefeld 1971, ISBN 3-87263-015-6 .
- Carl Gustav Calwer , Gustav Jäger (Ed.): CG Calwer's Käferbuch. 3. Edition. K. Thienemanns, Stuttgart 1876.
- H. v. Lengerken: Studies on the life phenomena of the Silphini (Coleoptera). In: Zoomorphology. Volume 33, No. 4, December 1983, pp. 654-666, Springer, Berlin / Heidelberg. doi: 10.1007 / BF00407572
Web links
- Thanatophilus sinuatus at Fauna Europaea