Cockchafer

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Cockchafer
Cockchafer (Melolontha melolontha), taking off

Cockchafer ( Melolontha melolontha ), taking off

Systematics
Order : Beetle (Coleoptera)
Subordination : Polyphaga
Family : Scarab beetle (Scarabaeidae)
Subfamily : Melolonthinae
Genre : Cockchafer ( Melolontha )
Type : Cockchafer
Scientific name
Melolontha melolontha
( Linnaeus , 1758)

The cockchafer ( Melolontha melolontha ), also known as Common Maikäfer known is a species in the family of scarab beetles (Scarabaeidae) from the kind of the cockchafer ( Melolontha ). Related species are the forest cockchafer and Melolontha pectoralis .

features

Cockchafer beetles are about two to three centimeters long (22 to 32 millimeters). The head, thorax and abdomen, with the exception of the pygidium, are black, the legs, elytra, and antennae are reddish brown. The coloration is quite variable, there are both lighter animals with a reddish brown pronotum and legs as well as dark ones, both of which are almost black. The flanks of the abdomen bear a striking series of white, triangular spots; Large parts of the body, including the pronotum and the elytra, have white, lying close-fitting hairs that are never completely covering, and the formation of the hairs is also variable. The end of the abdomen is not covered by the wing covers and tapering to a point, it is called pygidium , it is gender-specific in shape. On each wing cover you can see four shiny longitudinal ribs. The antennae have a fan-shaped antenna lobe. In the male these compartments consist of seven lamellas, in the female there are only six. The lamellae of the male are significantly longer than those of the female, almost twice as long.

Typical specimens can be distinguished from the related cockchafer species by the shape of the tip of the abdomen (pygidium) (see illustration under cockchafer ). However, this feature is variable and does not allow all individual animals to be addressed safely. In particular, to distinguish it from the rarer sister species Melolontha pectoralis , the tip of the parameters of the male mating apparatus may have to be compared for a reliable address. This is usually hidden in the abdomen and can only be examined by dissection. The Krell key enables reliable differentiation of the species.

Larvae

Larvae

The larvae have the typical Enger Ling -shape, they carry three strong pairs of legs are whitish colored with brown head capsule and c-shaped incurved. The head capsule has four-membered antennae and strong mandibles. They can be distinguished from other ground-dwelling scarab beetle larvae with the shape of a grub, especially in the formation of the last segment of the abdomen. In the Melolonthinae, this is apparently divided into two by a ring-shaped transverse furrow, so that the abdomen appears to consist of 10 segments, the last of which both have no stigmas, while further furrows or lines are not present. The transverse anal column on the last segment is only shallow, not like z. B. with the June beetles three-rayed through a deep incision upwards. The sternite of the last abdominal segment has a characteristic bristle pattern, which consists of a central, long double row of 21 to 30 bristles starting from the transverse anus and a wide bristle field in the rear half, with the double row protruding far beyond the field. The larvae of the cockchafer species are very similar and difficult to distinguish.

habitat

As its name suggests and in contrast to the similar forest cockchafer , the field cockchafer prefers open, unwooded habitats. The difference is not absolute, however, both types can occur in exposed old wood stands or on the edges of forests. The larvae require loose, moist soil that is easy to dig; they are absent in both swampy and very dry habitats. The larvae are found in a wide variety of habitats, including meadows, gardens, and other cultivated land.

Ecology and way of life

pairing
Mating, detail

After mating in spring, the females lay their eggs in the ground. To do this, they dig themselves in soft, especially sandy, soil to a depth of 15 to 25 centimeters. The 2 to 3 millimeter long, whitish eggs are laid in clutches of around 24, each female normally lays two such clutches. The larvae that hatch after 4 to 6 weeks and live in the ground are called grubs . They feed on the roots of various types of plants, both grasses and herbaceous species, and roots of woody plants may be peeled off or curled from the outside. Although the larvae are not species-specific ( polyphagous ) in their diet, they do not eat indiscriminately. In the food choice experiment, they preferred and thrived best with dandelion roots , followed by other herb species such as dock and yarrow , followed by some grasses ( fescue , lolch ), while many other types of grass (e.g. bluegrass and ostrich grass ) hardly developed successfully is possible. The larvae crawl through the ground in search of roots, covering distances of around 70 centimeters. They use carbon dioxide and a large number of soluble or volatile substances ( exudates ) released by the roots , for example acetone , 1-hexanol and sucrose , which they perceive with chemical sensory organs on antennas and buttons (palps), other substances such as Propionic acid and benzaldehyde , on the other hand, have a deterrent effect. In winter, the larva digs deeper into the ground to avoid frost. The cockchafer, like all related species, has three larval stages. The greatest damage to eating is caused by the third stage. The first overwintering takes place in the second larval stage. In the second year of life, the larvae continue to feed when the soil temperature also exceeds 7 ° C, usually in April. In late summer, the third larvae molt. This reaches a live weight of around 3.8 grams. After hibernating twice, the larvae pupate freely in a pupa chamber in the ground. The finished beetles hatch in autumn. However, these remain in the doll's cradle until the following May and only then crawl out of the earth, mostly in mass slip synchronized by the weather. The peak is usually a little later (two to three weeks) than with the forest cockchafer. In total, the development takes three years. The lifespan of the imaginal beetles is about four to six weeks. Most of the beetles die after mating and laying their eggs, but about a third of the females survive and lay eggs again after they have fled into a forest again and have matured, very few even manage a third time.

Due to the development cycle of several years, the generations with hatching in different years usually never come into direct contact with each other. Typically, they are not equally strong, but some are considerably more individual than the others. This leads to characteristic waves with mass occurrences every three (or four) years. Such years are called the cockchafer year. In southern Central Europe, field cockchafer usually have a three-year development cycle, but forest cockchafer a four-year development cycle, so that three or four-year waves result. The field cockchafer also has a four-year development from northern Central Europe. A four-year development is occasionally also observed further south, for example in some populations in the Czech Republic, a four-year cycle also occurs in high Swiss Alpine valleys.

After hatching, the adult beetles orient themselves optically in search of trees or forest edges, which they can recognize by the silhouette up to about three kilometers away, and then try to fly there. Structures such as buildings also lead to misorientation. The flight takes place almost exclusively at dusk. The beetles are able to use the polarization pattern of sunlight for orientation by means of special ommatidia on the upper edge of their eyes. They feed on the leaves of trees, especially oak and beech leaves , but sometimes also fruit trees. Mating, which can take several hours, takes place in the trees. The males orientate themselves on volatile leaf alcohols, which from z. E.g. leaves damaged by eating escape to locate the females; these did not attract females, and intact leaves did not attract either sex. After about 10 to 20 days of feeding, the females fly back to the open area to lay their eggs. They prefer open ground areas that are not covered with vegetation.

distribution

The species occurs in most of Europe, but is rare in the southern Mediterranean. The northern limit of the distribution is in southern Sweden. In the east, the distribution limit goes through Estonia, the European part of Russia and the Ukraine on the line Smolensk , Kursk , Kharkiv , Zaporizhia , Odessa .

Taxonomy

The species was first described by Carl von Linné as Scarabaeus melolontha . It is a type of the genus Melolontha described by Johann Christian Fabricius (the name actually comes from Étienne Louis Geoffroy , but this was suppressed for taxonomic purposes.) Fabricius called the species Melolontha vulgaris , this synonym was widely used until the middle of the 20th century. There are dozens of other, mostly very old, synonyms that were set up for color variants that are no longer recognized today. The species-rich genus has 10 European representatives, of which the three mentioned occur in Central Europe. With the help of the mtDNA , the Central European cockchafer species can be easily differentiated, this also applies to individuals who look intermediate after morphological addressing, so these are not hybrids , as was often assumed in the past . The species could therefore be easily distinguished using conventional DNA barcoding . According to the findings, it is unclear whether there are any natural hybrids between the species.

Economic importance

The cockchafer grubs are considered to be significant pests in agriculture when they multiply on a large scale . Root damage in meadows and pastures by the grubs often shows up in poor-growing spots that soon turn brown. Forestry damage is also reported, but here its importance is usually less than that of the forest cockchafer (in earlier reports, the species were often not differentiated). The damage caused by feeding on trees by the imaginal beetles is normally of minor importance, but in the case of mass reproduction it can lead to devastation and then also be significant for forestry. But also important is the third instar root consumption on trees, especially on young plants, e.g. B. in tree nurseries or orchards.

The previously very high populations of the cockchafer have declined sharply in Central Europe since the 1950s. Because of the high level of awareness of the species, this has been extensively reported (see under cockchafer ). Parallel to the increase in the forest cockchafer populations, the field cockchafer also became more common again from the 1980s and locally again reached mass populations ( gradations ). The reasons for both the decline and the recovery are unknown.

Enemies and Combat

Beetles and larvae like to be eaten by numerous bird species when they can reach them. Although the importance of birds is considered considerable, it is difficult to quantify. In a study on the Middle Rhine (Lorsch) the significant mortality factor for the type a pathogenic bacterium was that the Rickettsia belonging melolonthae Rickettsiella that there was about half the grubs victim. Sick grubs came to the surface of the soil in late autumn, where they perished; their bluish discoloration was striking (hence the “blue epidemic”). A regionally important antagonist is the parasitoid caterpillar fly Dexia rustica . The fly lays its eggs on the forest floor, the hatching young larvae then dig independently for grubs, which they invade. The parasite larva overwinters in the host , which it then kills when it hatches in spring.

The insect pathogenic fungus Beauveria brongniartii is also a major mortality factor for grubs . The species is commercialized e.g. B. offered under the trade name "Melocont Mushroom Barley" for biological pest control. Parasitic nematodes have also been suggested as control agents , such as strains of Heterorhabditis downesi , Heterorhabditis bacteriophora , Steinernema feltiae and other species. The nematode Steinernema glaseri (and another Steinernema strain) also proved to be effective, but there are serious concerns about its use in Central Europe because it is an American species.

Traditionally, insecticides such as DDT were used to control cockchafer in the forest, often sprayed from airplanes. This control method is now widely discredited because of its numerous ecological side effects, but it is still z. This is common in Poland, for example, where the neonicotinoid acetamiprid is used from helicopters. In Germany too, until recently, for. B. the phosphoric acid ester dimethoate sprayed against cockchafer in the forest.

Cockchafer and man

As rather large and common beetles that were also easy to catch, they were very popular with children as toys. The cockchafer were then separated from the children into three groups, depending on their color, with different exchange values: chimney sweeps (dark with little hair), millers (floury whitish hair) and emperors (reddish head and reddish breastplate, rare). The nursery rhyme Maikäfer, flieg and the fifth prank by Max and Moritz still give evidence of the frequency and popularity .

The frequency in the mass flight year 1938 can be seen in Schleswig-Holstein. At that time, a premium of 5 pfennigs was paid for every kilogram of cockchafer delivered, for which the Reich Ministry of Food was responsible. In Schleswig-Holstein a total of 192,812 kg cockchafer were billed, with a live weight of around one gram, that is almost 200 million beetles. With a mass increase in Bern in 1478/79, the magistrate knew no way out but to ask the church for help. Then the bishop of Lausanne against the "Inger" opened (elsewhere also "Passenger", this became later the white grub) a judicial process (see. Animal trial ), in which he was officially condemned and damned.

swell

  • HF Huiting, LG Moraal, FC Griepink & A. Ester: Biology, control and luring of the cockchafer, Melolontha melolontha. Literature report on biology, life cycle and pest incidence, current control possibilities and pheromones. Project Report, Applied Plant Research (Praktijkonderzoek Plant & Omgeving BV). Wageningen 2006. download
  • Melolontha melolontha. Interactive Agriculture Ecological Atlas of Russia and Neighboring Countries online

Web links

Commons : Field cockchafer  - collection of images, videos and audio files

Individual evidence

  1. ↑ a b c F.T. Krell (2004): Determination of larvae and adults of the Central European Melolontha species (Coleoptera, Scarabaeoidea). Laimburg Journal Volume 1 (2): 211-219.
  2. ^ R. Hauss & F. Schütte (1976): On the polyphagy of the grubs by Melolontha melolontha L. of plants from meadow and wasteland. Indicator for pest science, plant protection, environmental protection 49: 129–132.
  3. ↑ F. Schwertfeger (1939): Investigations on the migration of the Maikaferengerlings (Melolontha melolontha L. and Melolontha hippocastani F.). - Journal of Applied Entomology 26: 215-252, cited above. according to Thomas Hasler: Abundance and dispersion dynamics of Melolontha melolontha (L.) in intensive fruit orchards. Diss., ETH Zurich, 1986.
  4. ^ Elisabeth Johanna Eilers: Chemosensation and belowground host plant finding in Melolontha melolontha L. larvae. Diss., FU Berlin, 2012.
  5. ↑ M. Švestka (2010): Changes in the abundance of Melolontha hippocastani Fabr. And Melolontha melolontha (L.) (Coleoptera: Scarabaeidae) in the Czech Republic in the period 2003-2009. Journal of Forest Science 56 (9): 417-428.
  6. ↑ Thomas Hasler: Abundance and dispersion dynamics of Melolontha melolontha (L.) in intensive fruit orchards. Diss., ETH Zurich, 1986.
  7. ↑ Thomas Labhart, Eric P. Meyer, Leslie Schenker (1992): Specialized ommatidia for polarization vision in the compound eye of cockchafers, Melolontha melolontha (Coleoptera, Scarabaeidae). Cell and Tissue Research Volume 268, Issue 3: 419-429.
  8. ↑ A. Reinecke, J. Ruther, T. Tolasch, W. Francke, M. Hilker (2002): Alcoholism in cockchafers: orientation of male Melolontha melolontha towards green leaf alcohols. Science 89 (6): 265-269.
  9. ↑ Interactive Agriculture Ecological Atlas of Russia and Neighboring Countries
  10. ↑ ICZN (1994): Opinion 1754. Histoire abrégée des insectes qui se trouvent aux environs de Paris (Geoffroy, 1762): some generic names conserved (Crustacea, Insecta. Bulletin of Zoological Nomenclature Volume 51: 58-70.)
  11. ↑ T. Giannoulis, A.-M. Dutrillaux, Z. Mamuris, O. Montreuil, C. Stamatis, B. Dutrillaux (2011): Evolution of European Cockchafers (Melolonthinae: Scarabaeidae: Coleoptera): a morphological, molecular and chromosomal study of intra- and inter-specific variations. Bulletin of Entomological Research Volume 101, Issue 03: 345-352.
  12. ↑ Trevor A. Jackson (2006): Scarabs as pests. A continuing problem. Coleopterists Society Monograph Number 5: 102-119.
  13. ↑ for Austria: Andreas Kahrer, Bernhard Perny, Gottfried Steyrer, Hermann Hausdorf (2011): Maikäfer now also on the advance in Eastern Austria. Forest Protection Current No. 53: 5–10.
  14. ↑ a b O.F. Niklas (1960): Site influences and natural enemies as limiting factors for Melolontha larvae populations in a forest area (Lorsch Forestry Office, Hesse). Messages from the Federal Biological Research Center for Agriculture and Forestry Berlin-Dahlem Issue 101: 5-60.
  15. ↑ Dexia rustica in the UK Tachinid recording scheme .
  16. ↑ Tamás Lakatos & Tímea Tóth (2006): Biological Control of European Cockchafer Larvae (Melolontha melolontha L.), preliminary results. Journal of Fruit and Ornamental Plant Research Vol. 14 (Suppl. 3): 73-78.
  17. ↑ a b Zeynep Erbas, Cihan Gökce, Selçuk Hazir, Zihni Demirbag, İsmail Demir (2014): Isolation and identification of entomopathogenic nematodes (Nematoda: Rhabditida) from the Eastern Black Sea region and their biocontrol potential against Melolontha melolontha (Coleoptera: Scarabaeidae) larvae. Turkish Journal of Agriculture and Forestry 38: 187-197.
  18. ↑ Žiga Laznik, Tímea Toth, Tamás Lakatos, Matej Vidrih, Stanislav Trdan (2009): Efficacy of two strains of Steinernema feltiae (Filipjev) (Rhabditida: Steinernematidae) against third-stage larvae of common cockchafer (Melolontha melolontha [L.], Coleoptera, Scarabaeidae) under laboratory conditions. Acta agriculturae Slovenica, 93 (3): 293-299.
  19. ↑ Overview in Nematodes as biocontrol agents. edited by Parwinder S. Grewal, Ralf-Udo Ehlers, David I. Shapiro-Ilan. CABI publishing, 2005. ISBN 0-85199-017-7 .
  20. ↑ Martin Berner & Wolfgang Schnetter (2001): Effectiveness of entomopathogenic nematodes against cockchafer grubs (Melolontha melolontha and M. hippocastani). Communications from the German Society for General and Applied Entomology 13: 1–3
  21. ↑ Barbara Głowacka & Alicja Sierpińska (2012): Control of adult cockchafers Melolontha spp. with Mospilan 20 SP. Folia Forestalia Polonica, Series A, Vol. 54 (2): 109-115.
  22. ↑ Cockchafer and forest protection. On the cockchafer problem in the North Baden Rhine plain. Brochure, published by the Baden-Württemberg Ministry for Food and Rural Areas in April 2007.
  23. ↑ after: Walter Hase (1984): The cockchafer as a forest pest in Schleswig-Holstein. Publication series of the Natural Science Association Schleswig-Holstein Volume 54: 103-115.
  24. ^ S. Keller (1984): The other face of the cockchafer. Tagesanzeiger Magazin 19: 27-33. quoted according to Thomas Hasler: Abundance and dispersion dynamics of Melolontha melolontha (L.) in intensive fruit orchards. Diss., ETH Zurich, 1986.