European mole cricket ( Gryllotalpa gryllotalpa )
|Leach , 1815|
The mole crickets (Gryllotalpidae) are a family of grasshoppers . It includes around 100 species in six genera (plus some known only fossil). In Central Europe (including Germany, Austria and Switzerland) the European mole cricket ( Gryllotalpa gryllotalpa ) is the only species.
Etymology of the name "Mole Cricket"
The name "mole cricket" goes back to the European mole cricket; it stems from their characteristic appearance: on the one hand they have large grave shovels and live underground like moles , on the other hand they have (roughly) the body shape of large crickets and produce similar sounds. This is how the scientific name " Gryllotalpa " is composed; It is named after the Gryllidae , crickets, and the mole Talpa europea . The English name “mole cricket” also corresponds with this.
The name "Talpa", mole for the insect, was found in 1599 by the Italian Ferrante Imperato . The English naturalist Thomas Muffet calls it “Gryllo-Talpa” in the “Theatrum Insectorum” (published 1634). August Johann Rösel von Rosenhof , who describes the animal in his insect amusements (1749), speaks of the "winged mouth litter". This also mentions the popular name "Werre".
The first species to be scientifically described by Carl von Linné in 1758 was the European mole cricket under the name Gryllus (Acheta) gryllotalpa . Pierre André Latreille placed them in 1802 as the only species (monotypical) in the genus Gryllotalpa, which he had newly introduced . For this, William Elford Leach introduced the family Gryllotalpidae in 1815.
Mole crickets are usually relatively large, cylindrical, but dorsoventrally (from top to bottom) somewhat flattened, yellowish to dark brown colored crickets. The entire surface of the body is briefly covered with velvety hairs (“tomentose”), which is particularly easy to recognize from the pronotum and the grave bones. The head is conical, mostly drawn into the pronotum. He wears a pair of well-trained complex eyes and usually two ocelli . The antennae are thread-shaped and only of moderate length, about as long as the pronotum (as an exception within the "long-feeler" scare). The pronotum is always markedly enlarged and drawn down like a shield on the sides, with a longitudinal furrow on the top.
The most striking feature of the family are the enlarged front legs, which have been redesigned to form a ditch, which are slightly different in the two subfamilies. In the Gryllotalpinae, the widened and flattened femur has a shield-shaped or knife-shaped protrusion, the trochanter has receded. The most important grave organ is the tibia . This has four large fingers or thorns on the front edge, which are called dactyls (as an exception for the New Zealand genus Triasmecaptor only three). Of these, two are fixed and two are movable. When digging, the links are put together to create a wide, shovel-like surface. In the Scapteriscinae the anterior femur has no protrusion, instead the trochanter is present and elongated, it usually has an enlarged spine. The anterior tibes have only two movable dactyls. In both subfamilies, the first two tarsi members (tarsomeres) of the front legs are enlarged and also widened like a leaf. The rest of the tarsi are normal, they are used for running, but they are angled back when digging. The middle and rear legs of the mole crickets are not particularly redesigned, the rear legs are relatively poorly developed, so that the animals have no jumping ability. The splints of both pairs of legs have several groups of long thorns, the number and position of which are of diagnostic value. The tympanic organs used for hearing are also located on the fore tibia . Its opening is oval or partially covered by a cover-like projection and then slit-shaped.
Mole crickets are usually fully winged and capable of flight. In some genera and species, the hind wings or both wing pairs are shortened and thus the ability to fly has been lost. The forewings are transformed into coarse deck wings ( tegmina ). The thin hind wings are folded or rolled up when at rest and lie under the forewings, their tips protrude far beyond them, usually over the tip of the abdomen. The veining of the forewings is redesigned in the males (by which the otherwise very similar sexes can be differentiated): In the male, a large harp-shaped cell is formed in the middle of the wing, which in the female remains small and inconspicuous. This is used to amplify the sound when singing through stridulation . The wing veins are peculiarly modified in the mole crickets, numerous parallel veins directed towards the wing leading edge (branches of the subcosta) are striking. The abdomen of the Gryllotalpidae is unmodified and cylindrical and has two appendages at the end, the cerci . The ovipositor of the female is regressed and inoperative. The male reproductive organs are transformed in the family compared to the other crickets, a characteristic feature is, for example, the undifferentiated endophallus.
Sound production, pairing, life cycle
Male mole crickets stridulate to attract females. In addition, the animals produce warning sounds to other members of their own species, for example when two males face each other when they sing so-called rivals. Warning sounds are produced by both sexes. When singing, the cricket rubs the two parallel front wings on top of each other. A reinforced edge in the basal section of the wing's trailing edge, known as the plectrum, rubs over a toothed vein of the other wing called a file (this is a section of the cubitus ). A triangular cell called a harp and presumably adjacent, flexible wing sections are set in motion, which then amplify the sound produced. In the case of the mole crickets, both wings are designed in the same way and can each fulfill both functions; the specialization of most other crickets is not pronounced.
For further reinforcement, male mole crickets stridulate out of a specially designed part of their underground burrow. The acoustic part acts as a resonator , it has a wide, funnel-shaped opening to the outside, which opens into a small oval chamber from which a different number of further corridors branch off. When singing, the male sits with his head inward in the chamber and stretches his body out into the funnel-shaped passage (called "horn"). Due to its shape and dimensions, it amplifies the sound. Due to this construction method, the singing is preferably emitted upwards, into the air space. It is believed that flying females in particular are attracted by this. The song is species-specific and in many cases allows the species to be identified more easily than morphological features. The sound produced was described as "dull rolling or gurgling" or "dull shrill sound".
According to studies on the American species Gryllotalpa major, the hearing ability (as is typical for long-feeler terrors, via the tympanic organs in the fore tibia) is specifically designed in terms of frequency sensitivity for the chants of the species. A secondary maximum, however, indicates that they can probably hear the locating sounds of bats as well, so that they can try to escape them in flight by evasive movements.
The pairing takes place in the underground construction. The male sticks on a sessile spermatophore . The female then lays the eggs in small packages inside the underground passages, usually in special small chambers that are then sometimes closed. The nymphal stages are similar, as typical of the locusts, the Imagines in appearance and lifestyle. The generation duration is in many cases one year ( univoltin ), occasionally two generations occur in a year, or a generation takes two years to develop; the generation time for species and populations spreading north is usually longer than for southern ones. For some species, for example the European mole cricket, it is reported that the females care for their brood. According to this, the females guard clutches and young nymphs and occasionally lick the eggs to protect them from fungal growth.
Most of the time, the mole crickets live underground in self-made corridor systems. Nymphs in particular regularly come to the surface at night. Adults leave their burrows mainly in search of mating partners, most species fly regularly, even longer distances. Almost all species live exclusively in loose, easy-to-dig sandy or loam soils, almost always in moist or wet soils. They occur in both vegetation-free and dense soils. However, they do not tolerate flooded soils, they can be driven out of their burrows when the soil is flooded.
The structures of the mole crickets have only been examined in more detail in a few species. For the investigation, tunnels are filled with a resistant, hardening material and then the surrounding soil is removed. In Florida, Neoscapteriscus species built tunnels about 50 to 70 centimeters long, usually with two exit holes (making them Y-shaped). Gryllotalpa tunnels were significantly shorter at around 10 to 23 centimeters; possibly because they were not created in the sand, but in the harder clay.
Food and enemies
Depending on the species, mole crickets feed primarily on other ground-dwelling arthropods (carnivorous), predominantly herbivorous (herbivorous), both from roots and from above-ground parts of plants, or they are true omnivores (omnivores) that consume both.
Natural enemies of the mole crickets have been studied especially in the economically important species. Digger wasps of the genus Larra specialize in prey on mole crickets . These follow the crickets in their underground passages, paralyze them with a sting and cover them with eggs on the spot. The South American species Larra bicolor was specifically established in Florida for biological pest control of mole crickets of the genus Neoscapteriscus (introduced as neozoa ) . Insect- pathogenic nematodes of the genera Heterorhabditis and Steinernema , which attack mole crickets, were also tested for their suitability. The caterpillar fly Ormia depleta , another parasitoid of mole crickets, hunts them acoustically by targeting singing animals. The example of Puerto Rico shows that vertebrates can also be significant as predators , where there are indications that the artificial settlement of the little mongoose (to control rats) has reduced the population of lizards of the bottom-living species Ameiva exsul , which indirectly strongly reduces the mole crickets could have been promoted (also an example of the risks of biological pest control).
Systematics of the Gryllotalpidae
The family comprises a good 100 species in two subfamilies (plus one known only from fossil sources) and in eight recent genera
- Subfamily Gryllotalpinae
- Genus Gryllotalpella Rehn , 1917. 5 South American species
- Genus Gryllotalpa Latreille , 1802. 70 species in Europe, Africa, Asia, Australia, North America
- European Mole Cricket or Common Mole Cricket ( Gryllotalpa gryllotalpa )
- Genus Leptocurtilla Cadena-Castañeda , 2015. 3 species, South America
- Genus Neocurtilla Kirby , 1906. 6 species, America
- Genus Triasmecaptor Tindale , 1928. only species Triasmecaptor aotea . New Zealand
- Subfamily Scapteriscinae
Note : The so-called "Pygmy Mole Crickets" (family Tridactylidae ) (English: "pygmy mole crickets"), which only reach a body size of about 10 mm, do not belong to the Gryllotalpidae family, despite their name, but to the short-antennae terrors ( Caelifera). The similarities between the two families can be traced back more to a convergent development than to a common ancestor.
Australia and New Zealand
In Australia at least 12 species are known, all of which belong to the genus Gryllotalpa , around 10 other, so far not described species are suspected, some of which can be differentiated well based on the songs of the males. All species live close to the water, in wet soils, from rainforests to the tiniest puddles of water in the desert-like arid center of the continent. The two species widespread here, Gryllotalpa monanka and Gryllotalpa coarctata, can probably reach these isolated habitats due to their good flight ability. The only New Zealand species, Triamescaptor aotea , is taxonomically isolated and is placed in its own tribe . It is the only mole cricket with three teeth on the tibia of the forelegs that has been converted into a burrow .
In Europe there are 13 species, all of which belong to the genus Gryllotalpa , in Central Europe (including Germany, Austria and Switzerland) only the European Mole Cricket ( Gryllotalpa gryllotalpa ) is native.
Thirteen species of the family live in Africa (plus one endemic to Madagascar ), all of which belong to the genus Gryllotalpa . The species belong to two species groups, the africana group and the parva group. Many of the species are morphologically very similar and can only be determined up to the species in the male sex. The most common species, Gryllotalpa africana, is also found in the Canary Islands, in southern Europe (Portugal) and parts of South Asia, but is not as widespread as it was thought; many older statements relate to confusion with other similar species.
In North America there are only three native (autochthonous), but seven introduced (neozoic) species of the family. The “northern mole cricket” ( Neocurtilla hexadactyla ) is the most common species there (but it also occurs in South America, possibly only introduced there), the other two species are extremely rare. However, more attention is paid to the five species of the genus Neoscapteriscus naturalized from South America (they were included in the genus Scapteriscus until 2015 ), because they are very common in the southwest, especially in Florida, and are considered to be significant pests of lawns and agricultural crops.
South America has the most diverse mole cricket fauna of all continents. The genera Gryllotalpella , Scapteriscus and Leptocurtella are restricted to South America, Neoscapteriscus evolved here, but was later carried away ; most species still only live there. But the genus Gryllotalpa also has South American species. Most species live in the Neotropic , in the forest floors of tropical rainforests.
The genus Indioscaptor , with four species, is limited in its distribution to India. In addition, species of the widespread genus Gryllotalpa also occur in Asia. Seven species of the genus from China are given. The most common and widespread species, Gryllotalpa orientalis , has long been confused with Gryllotalpa africana , which probably does not even occur in Asia; however, not all of the find information has yet been checked.
Mole crickets and humans
A number of species of mole cricket are considered pests . In Africa, Gryllotalpa species cause considerable agricultural damage. The European mole cricket, which is rare in Central Europe today, can also cause damage to agriculture in other regions, for example in Russia . In Luzon , Philippines, gryllotalpa species also damage rice, corn and sugar cane fields, but are also collected and fried as food for humans.
Significant damage to ornamental lawns , golf courses and pastures has been reported in Florida by the four species of the genus Neoscapteriscus introduced from South America . The economic damage is estimated to be in the order of over $ 10 million a year. The root-eating species, especially Neoscapteriscus vicinus , are particularly harmful , while the purely predatory species only disturb seedlings or young plants through their burrowing activity. The animals were fought with contact insecticides such as chlordane , especially in agriculture, until it was banned in the 1970s due to massive environmental damage. As a result, extensive research carried out by the Institute of Food and Agricultural Science at the University of Florida on the possibilities of biological pest control led to the settlement of three antagonists from the natural habitat of the mole crickets : the digger wasp Larra bicolor , the parasitic nematode Steinernema scapterisci and the caterpillar fly Ormia depleta . Since then, the mole crickets are said to have become significantly rarer, a decrease in population size of around 95 percent is assumed.
Threat and species protection
Some species of mole crickets in Western Europe and America are endangered. However, the risk assessment often reaches its limits due to the underground way of life and the resulting poor traceability. The American Gryllotalpa major , which is rare today, is “data deficient”. In the "Risk Analysis of Germany's Locusts" published in 2002, the European Mole Cricket was classified in the Red List - Category 2 ( endangered ). The mole cricket is not protected in Germany.
In the medicine
The secretion that the mole crickets use for their defense has been used as a healing ointment in folk medicine for a long time . This liquid is currently being researched for its healing properties in naturopathy in the western world .
Phylogeny and Evolution
The mole crickets belong within the long-feeler terrors, together with the real crickets ( Gryllidae ), the Mogoplistidae and the ant crickets ( Myrmecophilidae ), in the superfamily of the crickets ( Grylloidea ). Some editors used to place them in a separate superfamily called Gryllotalpoidea, but this position is now considered unlikely. Traditionally, they were mostly seen as a sister group of the real crickets. According to recent research, their likely sister group could be the ant crickets.
Fossil mole crickets have been documented since the Cretaceous . The finds from the Cretaceous Period are assigned to the extinct subfamily Marchandiinae. Some poorly preserved fossil species are known as compression fossils from the Santana Formation of Brazil. A larva from the Albium of France preserved in amber already had two of the characteristic spurs on the tibia, while corresponding formations on the trochanter or femur were missing. Obviously it was already a digging shape, presumably in wet ground based on the circumstances of the find. Based on finds from the Eocene , the genus Pterotriasmecaptor was established, the species Pterotriasmecaptor americanus from the Green River Formation possessed three burial spurs on the tibia like the recent Triassic captor .
- Chirping and images of mole crickets (English)
- University of Florida IFAS, Mole crickets control , page on pest control of mole crickets in Florida, USA
- August Johann Rösel: The monthly published insect amusement, second part, which contains eight classes of different both domestic and some foreign insects: all according to their origin, metamorphosis and other wonderful properties, mostly described from personal experience, and in neatly illuminated coppers, depicted and imagined after life. Johann Joseph Fleischmann, Nuremberg, 1749. online at Google Books
- Oscar J. Cadena-Castañeda (2015): The phylogeny of mole crickets (Orthoptera: Gryllotalpoidea: Gryllotalpidae). Zootaxa 3985 (4): 451-490. doi: 10.11646 / zootaxa.3985.4.1
- H.C. Bennet-Clark (1970): The Mechanism and Efficiency of Sound Production in Mole Crickets. Journal of Experimental Biology 52: 619-652. Download PDF
- Family Gryllotalpidae. Singing Insects of North America (SINA), accessed October 9, 2015 by Thomas J. Walker .
- Shabnam Jafari, Mohammad Hossein Kazemi, Hossein Lotfalizadeh: Acoustic burrow structures of European mole crickets, Gryllotalpa gryllotalpa (Orth .: Gryllotalpidae) in Northwestern Iran. North-Western Journal of Zoology 11 (1), 2015, pp. 58-61.
- PeggyS.M. Hill, Harrington Wells, John R. Shadley: Singing from a constructed burrow: why vary the shape of the burrow mouth? Journal of Orthoptera Research 15 (1), 2006, pp. 23-29.
- Peter Detzel: The locusts of Baden-Württemberg. Ulmer Verlag, Stuttgart 1998, ISBN 3-8001-3507-8 . on p. 325.
- Daniel R. Howard, Andrew C. Mason, Peggy SM Hill (2008): Hearing and spatial behavior in Gryllotalpa major Saussure (Orthoptera: Gryllotalpidae). Journal of Experimental Biology 211: 3613-3618. doi: 10.1242 / jeb.023143
- Rick L. Brandenburg, Yulu Xia, AS Schoeman: Tunnel architecture of three species of mole crickets (Orthoptera: Gryllotalpidae). Florida Entomologist 85 (2), 2002, pp. 383-385.
- Ellis L. Matheny, Jr. (1981): Contrasting feeding habits of pest mole cricket species. Journal of Economic Entomology 74: 444-445. doi: 10.1093 / jee / 74.4.444
- DE Silcox & RL Brandenburg (2011): Good Content Analysis of Southern and Tawny Mole Crickets (Orthoptera: Gryllotalpidae: Scapertiscus). Florida Entomologist 94 (1): 117-118. doi: 10.1653 / 024.094.0118 (open access)
- JH Frank, JP Parkman, FD Bennett: Larra bicolor (Hymenoptera: Sphecidae), a Biological Control Agent of Scapteriscus Mole Crickets (Orthoptera: Gryllotalpidae), Established in Northern Florida. Florida Entomologist 78 (4), 1995, pp. 619-623.
- DA Potter & SK Braman: Ecology and Management of Turfgrass Insects Annual Review of Entomology 36, 1991, pp. 383-406.
- Marlene Zuk & Gita R. Kolluru (1998): Exploitation of Sexual Signals by Predators and Parasitoids. Quarterly Review of Biology 73 (4): 415-438.
- JH Frank, NE Vicente, NC Leppla: A history of mole crickets (Orthoptera: Gryllotalpidae) in Puerto Rico. Insecta Mundi 0004, 2007, pp. 1-10.
- Eades, D. Otte, MM Cigliano, H. Braun: Orthoptera Species File online. Version 5.0 accessed September 8, 2015.
- Daniel Otte: Australian Crickets (Orthoptera: Gryllidae). Monographs of The Academy of Natural Sciences of Philadelphia, No. 22, 2007, ISBN 978-1-4223-1928-4 . limited preview on Google Books
- Heller, K.-G., Korsunovskaya, O., Ragge, DR, Vedenina, V., Willemse, F., Zhantiev, RD, Frantsevich, L .: Check-List of European Orthoptera. Articulata Beiheft 7, 1998, pp. 1-61.
- B.C. Townsend: A revision of the Afrotropical mole-crickets (Orthoptera: Gryllotalpidae). Bulletin of the British Museum (Natural History), Entomology series Vol 46, 1983, pp. 175-203.
- David A. Nickle & James L. Castner (1984): Introduces species of mole crickets in the United States, Puerto Rico, and the Virgin Islands (Insecta: Gryllotalpidae). Annals of the Entomological Society of America 77: 450-465
- DC Eades, D. Otte, MM Cigliano, H. Braun: Orthoptera Species File online. Version 5.0 accessed October 14, 2015.
- Li Bin Ma, Sheng Quan Xu, Makio Takeda (2008): Study of the genus Gryllotalpa (Orthoptera, Gryllotalpidae) from China with description of a new species. Acta Zootaxonomica Sinica 33 (1): 14-17
- Interactive Agricultural Ecological Atlas of Russia and Neighboring Countries: Gryllotalpa gryllotalpa (L.) - Common Mole Cricket, accessed October 24, 2015.
- Candida B. Adalla & Cleofas R. Cervancia: Philippine edible insects: a new opportunity to bridge the protein gap of resource-poor families and to manage pests. In: Patrick B. Durst, Dennis V. Johnson, Robin N. Leslie, Kenichi Shono (eds.): Forest insects as food: humans bite back. Proceedings of a workshop on Asia-Pacific resources and their potential for development, 19-21 February 2008, Chiang Mai, Thailand. Food and Agriculture Organization of the United Nations (FAO), Regional Office for Asia and the Pacific, Bangkok, Thailand 2010, ISBN 978-92-5-106488-7 , pp. 154/155.
- Thomas J. Walker: Mole crickets in Florida and neighboring states (Orthoptera: Gryllotalpidae). Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Entomology Circular no.243 1982.
- JH Frank & TJ Walker: Permanent control of pest mole crickets (Orthoptera, Gryllotalpidae, Scapteriscus) in Florida. American Entomologist Volume 52, Number 3, 2006, pp. 138-144.
- Gryllotalpa major. The IUCN Red List of Threatened Species 2000
- S. Maas, P. Detzel, A. Staudt: Risk analysis of the grasshoppers in Germany - distribution atlas, risk classification and protection concepts . Landwirtschaftsverlag, Münster 2002, ISBN 3-7843-3828-3 .
- Eraldo Medeiros Costa Neto (2005): Entomotherapy, or the Medicinal Use of Insects. Journal of Ethnobiology 25 (1): 93-114. doi : 10.2993 / 0278-0771 (2005) 25 [93: EOTMUO] 2.0.CO; 2
- Markus M. Zimmer, Johannes Frank, John H. Barker, Hans Becker (2006): Effect of extracts from the Chinese and European mole cricket on wound epithelialization and neovascularization: in vivo studies in the hairless mouse ear wound model. Wound Repair and Regeneration 14: 142-151. doi: 10.1111 / j.1743-6109.2006.00104.x
- Ioana C. Chintauan-Marquier, Frédéric Legendre, Sylvain Hugel, Tony Robillard, Philippe Grandcolas, André Nel1, Dario Zuccon, Laure Desutter-Grandcolas (2015): Laying the foundations of evolutionary and systematic studies in crickets (Insecta, Orthoptera): a multilocus phylogenetic analysis. Cladistics (nline before print) doi: 10.1111 / cla.12114
- Hojun Song, Christiane Amédégnato, Maria Marta Cigliano, Laure Desutter-Grandcolas, Sam W. Heads, Yuan Huang, Daniel Otte, Michael F. Whiting (2015): 300 million years of diversification: elucidating the patterns of orthopteran evolution based on comprehensive taxon and gene sampling. Cladistics (online before print) doi: 10.1111 / cla.12116
- Sam W. Heads & Rafael G. Martins-Neto: Orthopterida: grasshoppers, crickets, locusts and stickinsects. In: David M. Martill, Günter Bechly, Robert F. Loveridge (Eds.): The Crato Fossil Beds of Brazil. Window into an Ancient World. Cambridge University Press. 2011, ISBN 978-0-521-30080-3 .
- Vincent Perrichot, Didier Neraudeau, Dany Azar, Jean-Jacques Menier, Andre Nel (2002): A new genus and species of fossil mole cricket in the Lower Cretaceous amber of Charente-Maritime, SW France (Insecta: Orthoptera: Gryllotalpidae). Cretaceous Research 23: 307-314. doi: 10.1006 / cres.2002.1011
- Anrej V. Gorochov & Conrad C. Labandeira: Eocene Orthoptera from Green River Formation of Wyoming (USA). Russian Entomologica Journal 21 (4), 2012, pp. 357-370.