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No other crickets have mole-like forelegs. Antennae shorter than body; foretibia with two or four strong blade-like projections; first two segments of foretarsus developed into blades; body cylindrical and covered with short dense pubescence; hindfemur not reaching tip of abdomen. Length 19-50 mm.
Mole crickets include the largest and the most destructive crickets in North America. Four of our seven species are immigrants.
Burrowing
Mole crickets spend nearly all their lives underground. They occupy extensive tunnel systems within which they can move, forward or backward, with great speed--as can be demonstrated by allowing one to tunnel in damp sand in a container with a transparent bottom (such as a glass bowl or clear plastic dish). When dug up, they do not leap away like other burrow-inhabiting crickets but dig their way back underground with powerful strokes of the forelegs. The dirt is simply forced aside. Other burrowing crickets have much slower digging techniques. Short-tailed crickets (Anurogryllus), for example, carry dirt away one mouthful at a time. Mole crickets often tunnel immediately beneath the surface and leave trails of pushed-up soil that resemble, in miniature, the surface tunnels of mammalian moles. The burrowing techniques of mole crickets restrict them to sandy, friable, or nearly saturated soils.
Flight
Although mole crickets appear heavy and clumsy, many are capable fliers. In some species, all individuals have the long hindwings necessary for flight. In others, some or all individuals have short hindwings and cannot fly. Capturing mole crickets as they end their flights at simulations of their conspecific calls or at bright lights is far easier than extracting them from soil.
Food
Mole crickets eat both plant and animal matter, with some species being mostly herbivorous and others mostly carnivorous. Our three species of two-clawed mole crickets (Scapteriscus) damage lawns, golf courses, pastures, and crops, mostly by feeding on roots and leaves but also by cutting roots and uprooting seedlings as they tunnel.
Oviposition and social behavior
Female mole crickets lack an external ovipositor and lay eggs in their burrows or in special chambers that they then seal off. The females of northern and European mole crickets stay with their eggs and young nymphs. It is not known when the relationship is terminated nor to what extent the mothers provide protection and food. Mole crickets have anal glands from which they can expel a sticky liquid that may thwart insect predators such as ants.
Mating occurs within the burrow and the male's courtship song can be heard issuing from the ground during the day as well as at night. Observations in glass-sided burrows reveal that the male sometimes enlarges the burrow to give the female room to mount. In at least one species, the northern mole cricket, matings are initiated tail-to-tail with the male lying on his back! A female may mate several times with the same male at intervals of 10 or 15 minutes, but once she no longer responds to the male's courtship, the pair fights and one leaves the burrow system. Perhaps in the wild the male leaves or is driven away, with the female taking over the tunnel system for egg laying
Life cycles
Mole crickets generally require a year or more to develop and they overwinter in all stages except the egg and small nymph. The only populations that have more than one generation per year are southern and short-winged mole crickets in south Florida. Two-year life cycles have been documented for the northern mole cricket in the Carolinas. Longer life cycles seem likely for more northern populations and for larger mole crickets, but these have not been studied.
Acoustic behavior
Since soil transmits sound poorly, crickets that remain earthbound are unlikely to use sound for long range communication. Indeed, the calling of mole crickets seems to be directed largely or entirely to those that are flying. In the two European and three U.S. species that have been most thoroughly studied, males construct special burrows for calling. These have horn-shaped openings to the outside and are of appropriate dimensions and design to augment the sound and project it skyward. Calling to the sky would make little sense except that in these species females fly prior to mating and can locate mating partners by flying to the source of calls. Such a link between flying and calling is evident in the three species of two-clawed mole crickets (Scapteriscus). The two that fly project their calls upward and flying conspecifics land at or near the calls. The one that cannot fly does not call, though it retains a courtship song.
Sound production by female mole crickets is somewhat a mystery. On rare occasions, when in contact with other mole crickets, females have been heard making sounds as they rub their wings together. S.M. Ulagaraj tape recorded and analyzed such sounds of a female tawny mole cricket. D.A. Nickle and T.C. Carlysle (1975) found toothed crossveins that may function in stridulation on the upper surface of the left forewing of females of tawny and southern mole crickets. They also reported male-like files (beneath the right forewing) in females of European and prairie mole crickets and summarized what was known of female sound production. Females seem to produce sounds during aggression or defense.
Two aspects of hearing in mole crickets are puzzling. Firstly, the young nymphs of two-clawed mole crickets have perfectly-formed, completely exposed tympana. In other crickets, the tympana are not evident in the early instars and are fully developed only in the adult. Dave Yager, in a pilot study, established that some southern mole cricket nymphs had hearing similar to, but generally less sensitive than, the adult. The function and exact nature of precocious hearing in mole crickets are unexplored. Secondly, all songs of mole crickets have dominant frequencies of less than 5 kHz, yet Nobuo Suga determined that the northern mole cricket (or a close Amazonian relative) hears best at 20-30 kHz. The specimens he studied had flown to lights. Perhaps mole crickets that fly have their hearing evolutionarily tuned to detect the ultrasonic pulses of insectivorous bats.
Remarks
The so-called "pygmy mole crickets" (Tridactylidae), once assumed to be closely related to mole crickets are now placed in a different suborder of Orthoptera (Caelifera). The sharing of mole-like features by these two insect groups is a result of evolutionary convergence rather than their having a mole-like common ancestor. Pygmy mole crickets are less than 10 mm and their forelegs have no tibial tympanum or tarsal blades.
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Die Maulwurfsgrillen (Gryllotalpidae) sind eine Familie der Heuschrecken. Sie umfasst etwa 100 Arten in sechs Gattungen (plus einige nur fossil bekannte). In Mitteleuropa ist die Europäische Maulwurfsgrille (Gryllotalpa gryllotalpa) die einzige Art.
Der Name „Maulwurfsgrillen“ geht auf die Europäische Maulwurfsgrille zurück; er rührt von ihrem charakteristischen Aussehen her: Einerseits besitzen sie große Grabschaufeln und leben unterirdisch wie Maulwürfe, auf der anderen Seite haben sie (in etwa) die Körperform von großen Grillen und erzeugen ähnliche Laute. So setzt sich auch der wissenschaftliche Name „Gryllotalpa“ zusammen; Namensgeber sind die Gryllidae, Grillen, und der Maulwurf Talpa europea. Damit korrespondiert auch der englische Name „mole cricket“.
Der Name „Talpa“, Maulwurf für das Insekt findet sich schon 1599 bei dem Italiener Ferrante Imperato. Der englische Naturforscher Thomas Muffet nennt es im „Theatrum Insectorum“ (herausgegeben 1634) „Gryllo-Talpa“. August Johann Rösel von Rosenhof, der das Tier in seinen Insekten-Belustigungen (1749) beschreibt, spricht vom „geflügelten Maul-Wurf“.[1] Dieser erwähnt auch den Volksnamen „Werre“.
Als erste Art wurde 1758 durch Carl von Linné die Europäische Maulwurfsgrille unter dem Namen Gryllus (Acheta) gryllotalpa wissenschaftlich beschrieben. Pierre André Latreille stellte sie 1802 als einzige Art (monotypisch) in die von ihm neu eingeführte Gattung Gryllotalpa. Für diese führte William Elford Leach 1815 die Familie Gryllotalpidae ein.
Maulwurfsgrillen[2] sind meist relativ große, zylindrische, aber dabei dorsoventral (von oben nach unten) etwas abgeflachte, gelblich- bis dunkelbraun gefärbte Grillen. Die gesamte Körperoberfläche ist kurz samtartig behaart („tomentiert“), besonders gut erkennbar am Pronotum und den Grabbeinen. Der Kopf ist konisch, meist etwas in den Halsschild eingezogen. Er trägt ein Paar gut ausgebildete Komplexaugen und in der Regel zwei Ocelli. Die Antennen sind fadenförmig und nur von moderater Länge, etwa so lang wie der Halsschild (als Ausnahme innerhalb der „Langfühler“schrecken). Der Halsschild (Pronotum) ist immer markant vergrößert und schildartig an den Seiten herabgezogen, mit einer Längsfurche auf der Oberseite.
Auffallendstes Merkmal der Familie sind die vergrößerten, zum Graben umgestalteten Vorderbeine, die bei den beiden Unterfamilien etwas unterschiedlich gestaltet sind. Bei den Gryllotalpinae trägt der verbreiterte und abgeflachte Femur einen schild- oder messerförmigen Vorsprung, der Trochanter ist rückgebildet. Wichtigstes Graborgan ist die Tibia. Diese besitzt am Vorderrand vier große Finger oder Dornen, die als Dactylen bezeichnet werden (als Ausnahme bei der neuseeländischen Gattung Triasmecaptor nur drei). Von diesen sind zwei fest sitzend und zwei beweglich. Beim Graben werden die Glieder aneinandergelegt, sodass eine breite, schaufelartige Fläche entsteht. Bei den Scapteriscinae besitzt der Vorderfemur keinen Vorsprung, dafür ist der Trochanter vorhanden und verlängert, er trägt meist einen vergrößerten Dorn. Die Vordertibien tragen bei ihnen nur zwei bewegliche Dactylen. Bei beiden Unterfamilien sind außerdem die ersten beiden Tarsenglieder (Tarsomeren) der Vorderbeine vergrößert und ebenfalls blattartig verbreitert. Die übrigen Tarsenglieder sind normal gestaltet, sie werden zum Laufen eingesetzt, aber beim Graben nach hinten abgewinkelt. Mittel- und Hinterbeine der Maulwurfsgrillen sind nicht besonders umgestaltet, die Hinterbeine relativ schwach entwickelt, so dass die Tiere kein Sprungvermögen besitzen. Die Schienen beider Beinpaare besitzen mehrere Gruppen langer Dornen, deren Zahl und Position von diagnostischem Wert ist. An den Vordertibien sitzen außerdem die zum Hören dienenden Tympanalorgane. Deren Öffnung ist oval oder durch einen deckelartigen Vorsprung teilweise verdeckt und dann schlitzförmig.
Maulwurfsgrillen sind in der Regel voll geflügelt und flugfähig. Bei einigen Gattungen und Arten sind die Hinterflügel oder beide Flügelpaare verkürzt und damit das Flugvermögen verlorengegangen. Die Vorderflügel sind zu derben Deckflügeln (Tegmina) umgestaltet. Die dünnen Hinterflügel sind in Ruhestellung eingefaltet oder eingerollt und liegen unter den Vorderflügeln, ihre Spitzen ragen nach hinten weit über diese hinaus, meist über die Hinterleibsspitze hinweg. Die Aderung der Vorderflügel ist bei den Männchen umgestaltet (woran die sonst sehr ähnlichen Geschlechter unterschieden werden können): Beim Männchen ist eine große harfenförmige Zelle in der Flügelmitte ausgebildet, die beim Weibchen klein und unauffällig bleibt. Diese dient zur Lautverstärkung beim Gesang durch Stridulation. Die Flügeladerung ist bei den Maulwurfsgrillen eigentümlich abgewandelt, auffallend sind zahlreiche parallele, zum Flügelvorderrand gerichtete Adern (Äste der Subcosta). Der Hinterleib der Gryllotalpidae ist unmodifiziert walzenförmig und trägt am Ende zwei Fortsätze, die Cerci. Der Ovipositor der Weibchen ist rückgebildet und funktionsuntüchtig. Die männlichen Begattungsorgane sind bei der Familie gegenüber den anderen Grillen umgebildet, ein charakteristisches Merkmal ist beispielsweise der undifferenzierte Endophallus.
Männliche Maulwurfsgrillen stridulieren, um Weibchen anzulocken. Daneben produzieren die Tiere Warnlaute an Artgenossen, zum Beispiel beim sogenannten Rivalengesang, wenn sich zwei Männchen gegenüber stehen. Warnlaute werden von beiden Geschlechtern erzeugt. Beim Gesang[3] reibt die Grille die beiden parallel gehaltenen Vorderflügel übereinander. Dabei reibt eine verstärkte Kante im basalen Abschnitt des Flügelhinterrands, die als Plektrum bezeichnet wird, über eine als Feile bezeichnete, mit Zähnen besetzte Ader des anderen Flügels (es handelt sich um einen Abschnitt des Cubitus). Dabei wird eine als Harfe bezeichnete, etwa dreieckige Zelle und vermutlich angrenzende, flexible Flügelabschnitte in Schwingungen versetzt, die dann den erzeugten Ton verstärken. Bei den Maulwurfsgrillen sind beide Flügel gleich gestaltet und können jeweils beide Funktionen erfüllen, die Spezialisierung der meisten anderen Grillen ist nicht ausgeprägt.
Zur weiteren Verstärkung stridulieren männliche Maulwurfsgrillen aus einem besonders gestalteten Teil ihres unterirdischen Baus heraus. Der akustische Teil wirkt als Resonator, er besitzt eine breite, trichterförmig erweiterte Öffnung nach außen, die in eine kleine ovale Kammer einmündet, von der eine unterschiedliche Anzahl weiterer Gänge abgeht. Beim Gesang sitzt das Männchen, mit dem Kopf nach innen, in der Kammer und streckt den Körper in den trichterförmigen Gang („Horn“ genannt) vor. Durch seine Form und Abmessungen verstärkt dieser den Schall. Der Gesang wird durch diese Konstruktionsweise vorzugsweise nach oben, in den Luftraum, abgegeben.[4] Es wird angenommen, dass vor allem fliegende Weibchen dadurch angelockt werden.[5][6] Der Gesang ist artspezifisch und erlaubt in vielen Fällen leichter als morphologische Merkmale die Bestimmung der Arten. Der erzeugte Ton wurde als „dumpfes Rollen oder Gurgeln“[7] bzw. „dumpfer Schrillton“[3] umschrieben.
Das Hörvermögen (wie typisch für Langfühlerschrecken, über Tympanalorgane in den Vordertibien) ist nach Untersuchungen an der amerikanischen Art Gryllotalpa major in seiner Frequenzempfindlichkeit spezifisch auf die Gesänge der Art(en) ausgelegt. Ein Nebenmaximum zeigt aber an, dass sie wohl auch die Ortungslaute von Fledermäusen hören können, so dass sie im Flug versuchen können, diesen durch Ausweichbewegungen zu entkommen.[8]
Die Paarung erfolgt im unterirdischen Bau. Dabei klebt das Männchen eine ungestielte Spermatophore auf. Anschließend legt das Weibchen die Eier in kleinen Paketen innerhalb der unterirdischen Gänge ab, meist in besonderen kleinen Kammern, die anschließend manchmal verschlossen werden. Die Nymphenstadien ähneln, wie typisch bei den Heuschrecken, den Imagines im Aussehen und in der Lebensweise. Die Generationsdauer ist in vielen Fällen ein Jahr (univoltin), gelegentlich kommen zwei Generationen im Jahr vor, oder eine Generation benötigt zwei Jahre zur Entwicklung; dabei ist die Generationsdauer bei nördlich verbreiteten Arten und Populationen in der Regel länger als bei südlichen. Bei einigen Arten, zum Beispiel auch der Europäischen Maulwurfsgrille,[7] wird über Brutfürsorge der Weibchen berichtet. Demnach bewachen die Weibchen Gelege und junge Nymphen und belecken die Eier gelegentlich, um sie vor Verpilzung zu schützen.
Die Maulwurfsgrillen leben die meiste Zeit unterirdisch in selbst angelegten Gangsystemen. Vor allem Nymphen kommen in der Nacht regelmäßig an die Oberfläche. Imagines verlassen ihre Bauten vor allem auf der Suche nach Paarungspartnern, die meisten Arten fliegen dazu regelmäßig, auch längere Strecken. Fast alle Arten leben ausschließlich in lockeren, gut grabfähigen Sand- oder Lehmböden, nahezu immer in feuchten oder nassen Böden. Sie kommen dabei sowohl in vegetationsfreien wie in dicht bewachsenen Böden vor. Sie tolerieren allerdings keine überschwemmten Böden, sie können mit Überflutung des Bodens aus ihrem Bau vertrieben werden.
Die Bauten der Maulwurfsgrillen sind nur bei wenigen Arten näher untersucht worden. Zur Untersuchung werden Tunnel mit einem widerstandsfähigen, aushärtendem Material ausgegossen und anschließend das umgebende Erdreich entfernt. In Florida bauten Neoscapteriscus-Arten Tunnel von etwa 50 bis 70 Zentimeter Länge, in der Regel mit zwei Ausgangslöchern (dadurch y-förmig). Gryllotalpa-Tunnel waren mit etwa 10 bis 23 Zentimeter deutlich kürzer; möglicherweise weil sie nicht im Sand, sondern im härteren Lehm angelegt wurden.[9]
Je nach Art ernähren sich Maulwurfsgrillen überwiegend räuberisch, dabei vor allem von anderen bodenlebenden Arthropoden (carnivor), überwiegend pflanzenfressend (herbivor), sowohl von Wurzeln wie auch von oberirdischen Pflanzenteilen, oder es handelt sich um echte Allesfresser (Omnivore), die beides verzehren.[10][11]
Natürliche Feinde der Maulwurfsgrillen wurden vor allem bei den ökonomisch bedeutsamen Arten untersucht. Auf Maulwurfsgrillen als Beute spezialisiert sind etwa Grabwespen der Gattung Larra. Diese verfolgen die Grillen in ihren unterirdischen Gängen, lähmen sie durch einen Stich und belegen sie an Ort und Stelle mit Eiern. Die südamerikanische Art Larra bicolor wurde gezielt zur biologischen Schädlingsbekämpfung von (als Neozoen eingeschleppten) Maulwurfsgrillen der Gattung Neoscapteriscus in Florida angesiedelt.[12] Insektenpathogene Nematoden der Gattungen Heterorhabditis und Steinernema, die Maulwurfsgrillen attackieren, wurden ebenfalls auf ihre Eignung getestet.[13] Die Raupenfliege Ormia depleta, ein weiterer Parasitoid von Maulwurfsgrillen, jagt diese akustisch, in dem sie gezielt singende Tiere anfliegt.[14] Dass auch Wirbeltiere möglicherweise als Prädatoren bedeutsam sein können, zeigt das Beispiel Puerto Rico, wo es Hinweise darauf gibt, dass die künstliche Ansiedlung des Kleinen Mungo (zur Rattenbekämpfung) die Population von Eidechsen der bodenlebenden Art Ameiva exsul vermindert hat, wodurch die Maulwurfsgrillen indirekt stark gefördert worden sein könnten (zugleich ein Beispiel für die Risiken der Biologischen Schädlingsbekämpfung).[15]
Die Familie umfasst gut 100 Arten in zwei Unterfamilien (plus eine nur fossil bekannte) und in acht rezenten Gattungen[16]
Anmerkung: Die so genannten „Pygmäen-Maulwurfsgrillen“ (Familie Tridactylidae) (englisch: „pygmy mole crickets“), die nur eine Körpergröße von etwa 10 mm erreichen, gehören trotz ihres Namens nicht in die Familie der Gryllotalpidae, sondern zu den Kurzfühlerschrecken (Caelifera). Die Ähnlichkeiten der beiden Familien ist mehr auf eine konvergente Entwicklung zurückzuführen als auf einen gemeinsamen Vorfahren.
In Australien sind mindestens 12 Arten bekannt, die alle zur Gattung Gryllotalpa gehören,[17] etwa 10 weitere, bisher nicht beschriebene Arten werden vermutet, die sich teilweise gut anhand der Gesänge der Männchen differenzieren lassen. Alle Arten leben nahe am Wasser, in nassen Böden, von Regenwäldern bis hin zu winzigsten Wasserlachen im wüstenartigen ariden Zentrum des Kontinents. Die beiden hier verbreiteten Arten, Gryllotalpa monanka und Gryllotalpa coarctata können diese isolierten Habitate wohl aufgrund ihrer guten Flugfähigkeit erreichen. Die einzige neuseeländische Art, Triamescaptor aotea, steht taxonomisch isoliert und wird in eine eigene Tribus gestellt, Es ist die einzige Maulwurfsgrille mit drei Zähnen an der zum Graben abgewandelten Tibia der Vorderbeine.
In Europa leben 13 Arten, die alle zur Gattung Gryllotalpa gehören,[18] in Mitteleuropa (unter Einschluss Deutschlands, Österreichs und der Schweiz) ist lediglich die Europäische Maulwurfsgrille (Gryllotalpa gryllotalpa) heimisch.
In Afrika leben 13 Arten der Familie (plus eine endemische auf Madagaskar), die alle zur Gattung Gryllotalpa gehören. Die Arten gehören in zwei Artengruppen, die africana-Gruppe und die parva-Gruppe. Viele der Arten sind morphologisch sehr ähnlich und nur im männlichen Geschlecht bis zur Art bestimmbar. Die häufigste Art, Gryllotalpa africana kommt auch auf den Kanarischen Inseln, in Südeuropa (Portugal) und Teilen Südasiens vor, ist aber nicht so weit verbreitet wie zeitweilig gedacht; viele ältere Angaben beziehen sich auf Verwechslungen mit ähnlichen anderen Arten.[19]
In Nordamerika leben nur drei heimische (autochthone), aber sieben eingeschleppte (neozoische) Arten der Familie.[20] Die „nördliche Maulwurfsgrille“ (Neocurtilla hexadactyla) ist die häufigste dort heimische Art (sie kommt aber auch in Südamerika vor, möglicherweise dort nur eingeschleppt), die beiden anderen Arten sind extrem selten. Mehr Aufmerksamkeit gilt aber den fünf aus Südamerika eingebürgerten Arten der Gattung Neoscapteriscus (sie wurden bis 2015 zur Gattung Scapteriscus gerechnet), weil diese im Südwesten, insbesondere in Florida, sehr häufig sind und als bedeutsame Schädlinge von Rasenflächen und landwirtschaftlichen Kulturen gelten.
Südamerika besitzt die diverseste Maulwurfsgrillen-Fauna aller Kontinente. Die Gattungen Gryllotalpella, Scapteriscus und Leptocurtella sind auf Südamerika beschränkt, Neoscapteriscus ist hier evolviert, aber später verschleppt worden; nach wie vor leben die meisten Arten aber nur dort. Aber auch die Gattung Gryllotalpa besitzt südamerikanische Arten. Die meisten Arten leben in der Neotropis, in Waldböden tropischer Regenwälder.[2]
Die Gattung Indioscaptor, mit vier Arten, ist in ihrer Verbreitung auf Indien beschränkt.[21] Außerdem kommen Arten der weit verbreiteten Gattung Gryllotalpa auch in Asien vor. So werden sieben Arten der Gattung aus China angegeben.[22] Die häufigste und am weitesten verbreitete Art, Gryllotalpa orientalis, wurde lange Zeit mit Gryllotalpa africana verwechselt, die vermutlich in Asien gar nicht vorkommt; es sind aber noch nicht alle Fundangaben überprüft worden.
Eine Reihe von Maulwurfsgrillen-Arten gelten als Schädlinge. In Afrika richten Gryllotalpa-Arten erhebliche landwirtschaftliche Schäden an.[19] Auch die in Mitteleuropa heute seltene Europäische Maulwurfsgrille kann in anderen Regionen Schäden in der Landwirtschaft verursachen, zum Beispiel in Russland.[23] Auf Luzon, Philippinen, schädigen Gryllotalpa-Arten zwar auch Reis-, Mais- und Zuckerrohrfelder, werden aber auch selbst gesammelt und gebraten als Nahrung für den Menschen genutzt.[24]
In Florida werden erhebliche Schäden an Zierrasen, Golfplätzen und Weiden durch die vier aus Südamerika eingeschleppten Arten der Gattung Neoscapteriscus gemeldet. Die wirtschaftlichen Schäden werden in der Größenordnung von über 10 Millionen Dollar pro Jahr abgeschätzt. Schädlich sind insbesondere die wurzelfressenden Arten, insbesondere Neoscapteriscus vicinus, während die rein räuberischen nur Keimlinge oder Jungpflanzen durch ihre Wühltätigkeit stören.[25] Die Tiere wurden, insbesondere in der Landwirtschaft, mit Kontaktinsektiziden wie Chlordan bekämpft, bis dieses in den 1970er Jahren wegen massiver Umweltschäden verboten wurde. Daraufhin durchgeführte umfangreiche Forschungsarbeiten[26] des Institute of Food and Agricultural Science der University of Florida zu den Möglichkeiten der biologischen Schädlingsbekämpfung führten zur Ansiedlung dreier Antagonisten aus der natürlichen Heimat der Maulwurfsgrillen: der Grabwespe Larra bicolor, des parasitischen Nematoden Steinernema scapterisci und der Raupenfliege Ormia depleta. Seitdem sollen die Maulwurfsgrillen signifikant seltener geworden sein, es wird ein Rückgang in der Populationsgröße um etwa 95 Prozent angenommen.
Einige Arten der Maulwurfsgrillen in Westeuropa und Amerika sind gefährdet. Allerdings stößt die Gefährdungsabschätzung aufgrund der unterirdischen Lebensweise und der dadurch schlechten Nachweisbarkeit oft an Grenzen. So ist die heute seltene amerikanische Gryllotalpa major „data deficient“.[27] In der 2002 erschienenen „Gefährdungsanalyse der Heuschrecken Deutschlands“ wurde die Europäische Maulwurfsgrille in die Rote Liste-Kategorie 2 (stark gefährdet) eingestuft.[28] Die Maulwurfsgrille ist in Deutschland nicht geschützt.
Das Sekret, das die Maulwurfsgrillen zu ihrer Verteidigung benutzen, wird in der Volksmedizin bereits seit langer Zeit als Heilsalbe verwendet.[29][30] Zurzeit wird diese Flüssigkeit auch in der westlichen Welt in der Naturheilkunde auf ihre heilende Wirkung erforscht.
Die Maulwurfsgrillen gehören innerhalb der Langfühlerschrecken, gemeinsam mit den Echten Grillen (Gryllidae), den Mogoplistidae und den Ameisengrillen (Myrmecophilidae), in die Überfamilie der Grillen (Grylloidea). Einige Bearbeiter stellten sie früher alternativ in eine Gryllotalpoidea genannte eigene Überfamilie, diese Position gilt heute aber als unwahrscheinlich. Traditionell wurden sie meist als Schwestergruppe der Echten Grillen angesehen. Nach neueren Untersuchungen könnten ihre wahrscheinliche Schwestergruppe aber eher die Ameisengrillen sein.[31][32]
Fossile Maulwurfsgrillen sind seit der Kreidezeit belegt. Die kreidezeitlichen Funde werden der ausgestorbenen Unterfamilie Marchandiinae zugeordnet. Einige schlecht erhaltene fossile Arten sind als Kompressionsfossilien aus der Santana-Formation Brasiliens bekannt.[33] Eine in Bernstein erhaltene Larve aus dem Albium Frankreichs[34] wies bereits zwei der charakteristischen Sporne an der Tibia auf, während entsprechende Bildungen an Trochanter oder Femur fehlten. Es handelte sich also offensichtlich bereits um eine grabende Form, den Fundumständen nach vermutlich in nassem Boden. Aufgrund von Funden aus dem Eozän wurde die Gattung Pterotriasmecaptor aufgestellt, die Art Pterotriasmecaptor americanus aus der Green-River-Formation besaß wie die rezente Triasmecaptor drei Grabsporne an den Tibien.[35]
Die Maulwurfsgrillen (Gryllotalpidae) sind eine Familie der Heuschrecken. Sie umfasst etwa 100 Arten in sechs Gattungen (plus einige nur fossil bekannte). In Mitteleuropa ist die Europäische Maulwurfsgrille (Gryllotalpa gryllotalpa) die einzige Art.
Mole crickets are members of the insect family Gryllotalpidae, in the order Orthoptera (grasshoppers, locusts, and crickets). Mole crickets are cylindrical-bodied, fossorial insects about 3–5 cm (1.2–2.0 in) long as adults, with small eyes and shovel-like fore limbs highly developed for burrowing. They are present in many parts of the world and where they have arrived in new regions, may become agricultural pests.
Mole crickets have three life stages: eggs, nymphs, and adults. Most of their lives in these stages are spent underground, but adults have wings and disperse in the breeding season. They vary in their diet: some species are herbivores, mainly feeding on roots; others are omnivores, including worms and grubs in their diet; and a few are largely predatory. Male mole crickets have an exceptionally loud song; they sing from a burrow that opens out into the air in the shape of an exponential horn. The song is an almost pure tone, modulated into chirps. It is used to attract females, either for mating, or for indicating favourable habitats for them to lay their eggs.
In Zambia, mole crickets are thought to bring good fortune, while in Latin America, they are said to predict rain. In Florida, where Neoscapteriscus mole crickets are not native, they are considered pests, and various biological controls have been used. Gryllotalpa species have been used as food in West Java, Vietnam, Thailand, Laos, and the Philippines.
Mole crickets vary in size and appearance, but most of them are of moderate size for an insect, typically between 3.2 and 3.5 cm (1.3 and 1.4 in) long as adults. They are adapted for underground life and are cylindrical in shape and covered with fine, dense hairs. The head, fore limbs, and prothorax are heavily sclerotised, but the abdomen is rather soft.[1] The head bears two threadlike antennae and a pair of beady eyes.[2] The two pairs of wings are folded flat over the abdomen; in most species, the fore wings are short and rounded and the hind wings are membranous and reach or exceed the tip of the abdomen; however, in some species, the hind wings are reduced in size and the insect is unable to fly. The fore legs are flattened for digging, but the hind legs are shaped somewhat like the legs of a true cricket; however, these limbs are more adapted for pushing soil, rather than leaping, which they do rarely and poorly. The nymphs resemble the adults apart from the absence of wings and genitalia; the wing pads become larger after each successive moult.[3]
The Gryllotalpidae are a monophyletic group in the order Orthoptera (grasshoppers, locusts, and crickets). Cladistic analysis of mole cricket morphology in 2015 identified six tribes, of which four were then new: Indioscaptorini (Scapteriscinae), Triamescaptorini, Gryllotalpellini and Neocurtillini (Gryllotalpinae), and two existing tribes, Scapteriscini and Gryllotalpini, are revised.[4] The group name is derived straightforwardly from Latin gryllus, cricket, and talpa, mole.[5]
Within the extant subfamilies, genera include:[6]
Mole cricket fossils are rare. A stem group fossil, Cratotetraspinus, is known from the Lower Cretaceous of Brazil.[9] Two specimens of Marchandia magnifica in amber have been found in the Lower Cretaceous of Charente-Maritime in France.[10] They are somewhat more abundant in the Tertiary amber of the Baltic and Dominican regions; impressions are found in Europe and the American Green River Formation.[11]
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Mole crickets are not closely related to the "pygmy mole crickets", the Tridactyloidea, which are in the grasshopper suborder Caelifera rather than the cricket suborder Ensifera. The two groups, and indeed their resemblance in form to the mammalian mole family Talpidae with their powerful front limbs, form an example of convergent evolution, both developing adaptations for burrowing.[12]
Adults of most species of mole cricket can fly powerfully, if not with agility, but males do so infrequently. The females typically take wing soon after sunset, and are attracted to areas where males are calling, which they do for about an hour after sunset. This may be to mate, or they may be influenced by the suitability of the habitat for egg-laying, as demonstrated by the number of males present and calling in the vicinity.[1]
Mole crickets undergo incomplete metamorphosis; when nymphs hatch from eggs, they increasingly resemble the adult form as they grow and pass through a series of up to 10 moults. After mating, a period of 1-2 weeks may occur before the female starts laying eggs. She burrows into the soil to a depth of 30 cm (12 in), (72 cm (28 in) has been seen in the laboratory), and lays a clutch of 25 to 60 eggs. Neoscapteriscus females then retire, sealing the entrance passage, but in Gryllotalpa and Neocurtilla species, the female has been observed to remain in an adjoining chamber to tend the clutch. Further clutches may follow over several months, according to species. Eggs must be laid in moist ground, and many nymphs die because of insufficient moisture in the soil. The eggs hatch in a few weeks, and as they grow, the nymphs consume a great deal of plant material either underground or on the surface. The adults of some species of mole crickets may move as far as 8 km (5.0 mi) during the breeding season. Mole crickets are active most of the year, but overwinter as nymphs or adults in cooler climates, resuming activity in the spring.[1]
Mole crickets live almost entirely below ground, digging tunnels of different kinds for the major functions of life, including feeding, escape from predators, attracting a mate (by singing), mating, and raising of young.[13]
Their main tunnels are used for feeding and for escape; they can dig themselves under ground very rapidly, and can move along existing tunnels at high speed both forwards and backwards. Their digging technique is to force the soil to either side with their powerful, shovel-like fore limbs, which are broad, flattened, toothed, and heavily sclerotised (the cuticle is hardened and darkened).[13]
Males attract mates by constructing specially shaped tunnels in which they sing.[13] Mating takes place in the male's burrow; the male may widen a tunnel to make room for the female to mount, though in some species, mating is tail-to-tail.[13] Females lay their eggs either in their normal burrows or in specially dug brood chambers, which are sealed when complete in the case of the genus Neoscapteriscus[13] or not sealed in the case of genera Gryllotalpa and Neocurtilla.
Male mole crickets sing by stridulating, always under ground.[14] In Gryllotalpa gryllotalpa, the song is based on an almost pure tone at 3.5 kHz, loud enough to make the ground vibrate 20 cm all round the burrow; in fact, the song is unique in each species. In G. gryllotalpa, the burrow is somewhat roughly sculpted; in G. vineae, the burrow is smooth and carefully shaped, with no irregularities larger than 1 mm. In both species, the burrow has two openings at the soil surface; at the other end is a constriction, then a resonating bulb, and then an escape tunnel. A burrow is used for at least a week. The male positions himself head down with his head in the bulb, and his tail is near the fork in the tunnel.[14][16]
Mole crickets stridulate like other crickets by scraping the rear edge of the left fore wing, which forms a plectrum, against the lower surface of the right fore wing, which has a ratchet-like series of asymmetric teeth; the more acute edges face backwards, as do those of the plectrum. The plectrum can move forward with little resistance, but moving it backwards makes it catch each tooth, setting up a vibration in both wings. The sound-producing stroke is the raising (levation) of the wings. The resulting song resembles the result of modulating a pure tone with a 66-Hz wave to form regular chirps. In G. vineae, the wing levator muscle, which weighs 50 mg, can deliver 3.5 milliwatts of mechanical power; G. gryllotalpa can deliver about 1 milliwatt. G. vineae produces an exceptionally loud song from half an hour after sunset, continuing for an hour; it can be heard up to 600 m away. At a distance of 1 m from the burrow, the sound has a mean power over the stridulation cycle up to 88 decibels; the loudest recorded peak power was about 92 decibels; at the mouths of the burrow, the sound reaches around 115 decibels. G. gryllotalpa can deliver a peak sound pressure of 72 decibels and a mean of about 66 decibels. The throat of the horn appears to be tuned (offering low inductive reactance), making the burrow radiate sound efficiently; the efficiency increases when the burrow is wet and absorbs less sound. Mole crickets are the only insects that construct a sound-producing apparatus. Given the known sensitivity of a cricket's hearing (60 decibels), a night-flying G. vineae female should be able to detect the male's song at a range of 30 m; this compares to about 5 m for a typical Gryllus cricket that does not construct a burrow.[14]
The loudness of the song is correlated with the size of the male and the quality of the habitat, both indicators of male attractiveness. The loudest males may attract 20 females in one evening, while a quieter male may attract none. This behaviour enables acoustic trapping; females can be trapped in large numbers by broadcasting a male's song very loudly.[17][18][19]
Mole crickets vary in their diets; some like the tawny mole cricket are herbivores, others are omnivores, feeding on larvae, worms, roots, and grasses, and others like the southern mole cricket are mainly predacious.[20][21] They leave their burrows at night to forage for leaves and stems, which they drag underground before consumption, as well as consuming roots underground.[3]
Besides birds, toads, and insectivorous mammals, the predators of mole crickets include subterranean assassin bugs, wolf spiders, and various beetles.[22] The South American nematode Steinernema scapterisci kills Neocapteriscus mole crickets by introducing bacteria into their bodies, causing an overwhelming infection.[23] Steinernema neocurtillae is native to Florida and attacks native Neocurtilla hexadactyla mole crickets.[24] Parasitoid wasps of the genus Larra (Hymenoptera: Crabronidae) attack mole crickets, the female laying an egg on the external surface of the mole cricket, and the larva developing externally on the mole cricket host. Ormia depleta (Diptera: Tachinidae) is a specialized parasitoid of mole crickets in the genus Neoscapteriscus; the fly's larvae hatch from eggs inside her abdomen; she is attracted by the call of the male mole cricket and deposits a larva or more on any mole cricket individual (just as many females as males) with which she comes in contact.[25] Specialist predators of mole cricket eggs in China and Japan include the bombardier beetle Stenaptinus jessoensis, whereas in South America, they include the bombardier beetle Pheropsophus aequinoctialis (Coleoptera: Carabidae); the adult beetle lays eggs near the burrows of mole crickets, and the beetle larvae find their way to the egg chamber and eat the eggs.[26] Fungal diseases can devastate mole cricket populations during winters with sudden rises of temperature and thaws.[27] The fungus Beauveria bassiana can overwhelm adult mole crickets[28] and several other fungal, microsporidian, and viral pathogens have been identified.[22] Mole crickets evade predators by living below ground, and vigorously burrowing if disturbed at the surface. As a last-ditch defence, they eject a foul-smelling brown liquid from their anal glands when captured;[29] they can also bite.[30]
Mole crickets are relatively common, but because they are nocturnal and spend nearly all their lives under ground in extensive tunnel systems, they are rarely seen. They inhabit agricultural fields and grassy areas. They are present in every continent except Antarctica; by 2014, 107 species had been described and more species are likely to be discovered, especially in Asia. Neoscapteriscus didactylus is a pest species, originating in South America; it has spread to the West Indies and New South Wales in Australia.[31] Gryllotalpa africana is a major pest in South Africa; other Gryllotalpa species are widely distributed in Europe, Asia, and Australia.[32] They are native to Britain (as to Western Europe), but the former population of G. gryllotalpa may now be extinct in mainland Britain,[33] surviving in the Channel Islands.[34]
Invasive species are those that cause harm in their newly occupied area, where biological control may be attempted. The first-detected invasive mole cricket species was Neoscapteriscus didactylus, a South American species reported as a pest in St. Vincent, West Indies, as early as 1837; by 1900, it was a major agricultural pest in Puerto Rico. It had probably slowly expanded its range northwards, island by island, from South America.[31] The only biological control program against N. didactylus was in Puerto Rico, and it succeeded in establishing the parasitoid wasp Larra bicolor from Amazonian Brazil.[35] In 2001, N. didactylus in Puerto Rico seemed to be a pest only in irrigated crops and turf. Small-scale experimental applications of the nematode Steinernema scapterisci were made in irrigated turf, but survival of the nematode was poor.[36] Very much later, this same species was reported as a pest in Queensland, Australia, presumably arriving by ship or plane.[37] The next-detected invasive species was in the late 19th century in Hawaii, probably by ship. It was named as Gryllotalpa africana, but much later as perhaps G. orientalis. It was not identified as Gryllotalpa krishnani until 2020.[38] It attacked sugarcane and was targeted with Larra polita from the Philippines in 1925, apparently successfully.[39]
The next detection was in Georgia, USA, and at that time was assumed to be N. didactylus from the West Indies.[2] It was, in fact, three South American Neoscapteriscus species, N. abbreviatus, N . vicinus, and N. borellii, probably having arrived in ship ballast. They caused major problems for decades as they spread in the Southeastern USA.[40]Scapteriscus mole cricket populations had built up since the early decades of the 20th century and damaged pastures, lawns, playing fields, and vegetable crops. From the late 1940s, chlordane had been the insecticide of choice to control them, but when chlordane was banned by the U.S. EPA in the 1970s, ranchers were left with no economic and effective control method. Especially to aid Florida ranchers, a project that became known as the UF/IFAS Mole Cricket Research Program was initiated in 1978. In 1985, a multiple-authored report was published on accomplishments.[41] In 1988, an account was published on prospects for biological control,[42] and in 1996 an account of promising results with biological control.[43] The program ended in 2004 after 25 years of running monitoring stations, and in 2006 a summary publication announced success: a 95% reduction in mole cricket numbers in northern Florida, with biological control agents spreading potentially to all parts of Florida.[44] Efforts to use Larra bicolor as a biological control agent in Florida began by importing a stock from Puerto Rico. It became established in a small area of southeastern Florida, but had little effect on Neoscapteriscus populations.[45] A stock from Bolivia became established in northern Florida and spread widely (with some help) to most of the rest of the state and neighboring states.[46] Its survival depends upon the availability of suitable nectar sources.[47][48]
Once gravid female Ormia depleta flies were found to be attracted to the song of Neoscapteriscus males in South America,[49] a path to trap these flies with synthetic mole cricket songs was opened. Experimentation then led to a rearing method.[50] Laborious rearing of over 10,000 flies on mole cricket hosts allowed releases of living fly pupae at many sites in Florida from the far northwest to the far south, mainly on golf courses, and mainly in 1989-1991. Populations were established, began to spread, and were monitored by use of synthetic mole cricket song. Eventually, the flies were found to have a continuous population from about 29°N then south to Miami, but the flies failed to survive the winter north of about 29°N. Shipment and release of the flies to states north of Florida was thus a wasted effort. As the flies had been imported from 23°S in Brazil and could not overwinter north of 29°N, whether flies from 30°S in Brazil might survive better in northern Florida was investigated in 1999, but they did not.
The third biological control agent to target Neoscapteriscus in Florida was the South American nematode Steinernema scapterisci.[23] Small-scale releases proved it could persist for years in mole cricket-infested sandy Florida soils. Its use as a biopesticide against Neoscapteriscus was patented, making it attractive to industry. Industrial-scale production on artificial diet allowed large-scale trial applications in pastures[51] and on golf courses,[52] which succeeded in establishing populations in several counties, and these populations spread, but sales were disappointing, and the product was withdrawn from the market in 2014. Although experimental application was made in states north of Florida, only in southern Georgia was establishment of the nematode verified, suggesting little interest in the other states.
The main damage done by mole crickets is as a result of their burrowing activities. As they tunnel through the top few centimetres of soil, they push the ground up in little ridges, increasing evaporation of surface moisture, disturbing germinating seeds, and damaging the delicate young roots of seedlings.[2] They are also injurious to turf and pasture grasses as they feed on their roots, leaving the plants prone to drying out and damage by use.[3]
In their native lands, mole crickets have natural enemies that keep them under control.[53] This is not the case when they have been accidentally introduced to other parts of the world. In Florida from the 1940s through the 1980s, they were considered pests and were described as "a serious problem". Their population densities have since declined greatly. A University of Florida entomology report suggests that South American Neoscapteriscus mole crickets may have entered the United States at Brunswick, Georgia, in ship's ballast from southern South America around 1899, but were at that time mistakenly believed to be from the West Indies.[40] One possible remedy was biological pest control using the parasitoidal wasps Larra bicolor.[54] Another remedy that has been successfully applied is use of the parasitic nematode Steinernema scapterisci. When this is applied in strips across grassland, it spreads throughout the pasture (and potentially beyond) within a few months and not only controls the mole crickets, but also remains infective in the soil for future years.[39]
In Zambia, Gryllotalpa africana is held to bring good fortune to anyone who sees it.[55] In Latin America, Scapteriscus and Neocurtilla mole crickets are said to predict rain when they dig into the ground.[56] In Japan in the past, they seem to have been associated with the worms/corpses/bugs that announce a person's sins to heaven in the Koshin/Koushin belief.
Gryllotalpa mole crickets have sometimes been used as food in West Java and Vietnam.[57] In Thailand, mole crickets (Thai: กระชอน) are valued as food in Isan. They are usually eaten fried along with sticky rice.[58]
In the Philippines, they are served as a delicacy called camaro in the province of Pampanga[59][60] and are a tourist attraction.[61][62] They are also served in parts of Northern Luzon.[57]
Mole crickets are members of the insect family Gryllotalpidae, in the order Orthoptera (grasshoppers, locusts, and crickets). Mole crickets are cylindrical-bodied, fossorial insects about 3–5 cm (1.2–2.0 in) long as adults, with small eyes and shovel-like fore limbs highly developed for burrowing. They are present in many parts of the world and where they have arrived in new regions, may become agricultural pests.
Mole crickets have three life stages: eggs, nymphs, and adults. Most of their lives in these stages are spent underground, but adults have wings and disperse in the breeding season. They vary in their diet: some species are herbivores, mainly feeding on roots; others are omnivores, including worms and grubs in their diet; and a few are largely predatory. Male mole crickets have an exceptionally loud song; they sing from a burrow that opens out into the air in the shape of an exponential horn. The song is an almost pure tone, modulated into chirps. It is used to attract females, either for mating, or for indicating favourable habitats for them to lay their eggs.
In Zambia, mole crickets are thought to bring good fortune, while in Latin America, they are said to predict rain. In Florida, where Neoscapteriscus mole crickets are not native, they are considered pests, and various biological controls have been used. Gryllotalpa species have been used as food in West Java, Vietnam, Thailand, Laos, and the Philippines.
Los grillotálpidos (Gryllotalpidae) son una familia de ortópteros. Esta familia incluye 11 géneros y más de 100 especies descritas. El nombre científico deriva del latín 'gryllus' que significa grillo.
Insectos grandes y medianos, con un cuerpo alargado, cubiertos de pelos gruesos y delgados. Los representantes de la familia alcanzan una longitud de 5-8 cm, llevan un estilo de vida subterráneo, viven en los visones excavados por ellos. Son muy diferentes de otros grillos (Grylloidea) con un pronoto muy desarrollado y grande, antenas relativamente cortas, que solo se extienden ligeramente más allá del margen posterior del pronoto, y patas delanteras fuertemente modificadas adaptadas para cavar y moverse en el suelo. La coloración del cuerpo y el abdomen en la parte superior suele ser de color marrón oscuro, brillante hacia la parte inferior, del mismo color y extremidades. Abdomen en la parte inferior de color marrón-amarillo, visualmente parece sedoso debido a la presencia de una cubierta densa de pequeños pelos dorados. La cabeza y el tórax son de color marrón oscuro.
Los adultos de la mayoría de las especies de grillos topo pueden volar poderosamente, si no con agilidad, pero los machos lo hacen con poca frecuencia. Las hembras suelen volar poco después de la puesta del sol y se sienten atraídas por las áreas donde los machos llaman, lo que hacen durante aproximadamente una hora después de la puesta del sol. Esto puede ser para aparearse o puede estar influenciado por la idoneidad del hábitat para la puesta de huevos, como lo demuestra el número de machos presentes y llamando en las cercanías. Esto puede ser para aparearse o puede estar influenciado por la idoneidad del hábitat para la puesta de huevos, como lo demuestra el número de machos presentes y llamando en las cercanías.
Los grillos topo sufren una metamorfosis incompleta; cuando las ninfas eclosionan de los huevos, se parecen cada vez más a la forma adulta a medida que crecen y atraviesan una serie de hasta 10 mudas. Después del apareamiento, puede ocurrir un período de 1-2 semanas antes de que la hembra comience a poner huevos. Ella excava en el suelo a una profundidad de 30 cm (12 plg), (72 cm (28 plg) se ha visto en el laboratorio), y pone una puesta de 25 a 60 huevos. Las hembras Neoscapteriscus luego se retiran, sellando el pasaje de entrada, pero en las especies Gryllotalpa y Neocurtilla, se ha observado que la hembra permanece en una cámara contigua para cuidar la nidada. Pueden producirse más nidadas durante varios meses, según la especie. Los huevos deben depositarse en suelo húmedo y muchas ninfas mueren debido a la falta de humedad en el suelo. Los huevos eclosionan en unas pocas semanas y, a medida que crecen, las ninfas consumen una gran cantidad de material vegetal, ya sea bajo tierra o en la superficie. Los adultos de algunas especies de grillos topo pueden desplazarse hasta 8 km (5 mi) durante la temporada de cría. Los grillos topo están activos la mayor parte del año, pero hibernan como ninfas o adultos en climas más fríos, reanudando su actividad en la primavera.
Tiene una distribución holártica y neártica. Muchas especies han invadido lugares lejos de su distribución original.
Los grillotálpidos (Gryllotalpidae) son una familia de ortópteros. Esta familia incluye 11 géneros y más de 100 especies descritas. El nombre científico deriva del latín 'gryllus' que significa grillo.
Courtilières
Les Gryllotalpidae sont une famille d'Orthoptera ensifères, plus communément appelés Courtilières ou Taupes-grillons. Ce sont des insectes fouisseurs, aux pattes avant transformées pour creuser.
La famille a été décrite par le naturaliste britannique William Elford Leach en 1815[1].
Selon Orthoptera Species File (19 mai 2012)[2] :
Courtilières
Les Gryllotalpidae sont une famille d'Orthoptera ensifères, plus communément appelés Courtilières ou Taupes-grillons. Ce sont des insectes fouisseurs, aux pattes avant transformées pour creuser.
I Grillotalpidi (Gryllotalpidae Leach, 1815) sono una famiglia di insetti ortotteri del sottordine Ensifera.[1]
Questi insetti hanno un corpo molto robusto, di colore bruno, cilindrico e coperto da una corta pubescenza vellutata. Il capo, munito di occhi piccoli e antenne corte, è più stretto del torace. Il protorace è massiccio, protetto da uno scudo chitinoso. Le zampe sono corte e massicce, specialmente quelle anteriori, munite persino di denti da scavo (zampe fossorie).
Sono insetti fossori, che conducono la loro esistenza sottoterra.[1]
Sono polifagi, ma non disdegnano larve di altri insetti, quando le trovano.
La famiglia è presente in tutti i continenti esclusa l'Antartide.[2]
La famiglia comprende i seguenti generi:[1]
I Grillotalpidi (Gryllotalpidae Leach, 1815) sono una famiglia di insetti ortotteri del sottordine Ensifera.
Gryllotalpidae trata-se de uma pequena família monofilética, da ordem dos ortópteros (gafanhotos, esperanças e grilos), que contempla mais de 100 espécies distribuídas em três subfamílias (duas existentes e uma fóssil) e que, provavelmente, surgiu entre o final do Jurássico e o início do Cretáceo. A história taxonômica do grupo começa quando Linnaeus (1758) descreveu a espécie Gryllus (Acheta) gryllotalpa. Em 1802, Lattreille descreveu o gênero Gryllotalpa, transferindo a espécie de Linnaeus para status de gênero. Somente em 1815, Leach estabeleceu a família Gryllotalpidae, incluindo a espécie Gryllotalpa gryllotalpa.[1]
São insetos mundialmente distribuídos, exceto nas regiões polares[2]. A maioria de suas espécies ocorre em zonas tropicais e alguns em zonas temperadas.[1] Nesta família estão inclusos alguns dos ortópteros mais distintos, por possuírem pernas dianteiras bem desenvolvidas utilizadas para cavar túneis e galerias profundas no solo, onde se abrigam e acessam as raízes das plantas, onde se alimentam. [3][4] Por isso, se tornaram importantes pragas de gramíneas, plantações e campos de golfe.[5] Os danos são de forma direta e indireta. Sendo direto por conta de cortar o caule e se alimentar das raízes, e indiretamente devido as galerias que afetam diretamente a germinação das sementes. [6]São ativos durante a noite e os machos adultos são capazes de produzir sons bem altos.[4]
As espécies desta família são conhecidas popularmente pelos nomes de ralo (Portugal), paquinha (Brasil), cachorro-d'água, cachorrinho-da-terra, grilo-toupeira, grilotalpa, entre outros.[7]
O voo das paquinhas pode atingir 15 km durante condições climáticas favoráveis, o que faz com que indivíduos adultos possam dispersar de um campo para outro sem muita dificuldade. E é muito provável que fêmeas grávidas postulem seus ovos em um campo e logo voem para outro, causando uma ampla dispersão da espécie. Entretanto, condições climáticas afetam diretamente o voo das paquinhas, que raramente voam em noites frias. Além disso, são frequentemente vistas voando, em grande número, após dias de chuva, especialmente depois de um longo período de seca, indicando que seu sistema de tocas foi destruído. Os adultos que voam logo após a chuva podem facilmente construir novas tocas no solo úmido. Outros fatores que podem influenciar no voo das paquinhas são: a disponibilidade de recursos, o estágio ontogenético, a intensidade da luz (são ativos à noite) e o fator sexual (o percentual de fêmeas com esperma na espermateca aumenta conforme a temporada de voo progride).
As tocas formadas pelas paquinhas podem ser classificadas de duas maneiras: tocas para viver, que compreende as tocas construídas por ambos os sexos para se esconder e se alimentar; e tocas de canto, construídas somente por alguns machos, para amplificar o efeito do som de corte.
As tocas para viver podem ser divididas em:
As tocas de canto consistem em um bulbo acústico com uma a quatro câmaras de entrada em forma de chifres. A abertura da(s) câmara(s) de entrada pode variar em forma, de acordo com a espécies. E o bulbo apresenta um túnel de saída, que vai se afastando dos funis e se conecta com a rede principal de tocas, o que dá maior proteção para o macho e sua parceira (uma vez que ela tenha localizado sua toca) ou fornece uma rota de fuga, caso seu canto atraia um predador.
Outro tipo de toca construída é a com finalidade de oviposição de ovos. As fêmeas escavam tocas profundas e acumulam alimentos, realizando a oviposição no fundo. Após, elas fecham a entrada da toca, para sua proteção e da prole. A fêmea cuida da prole recém nascida e morre antes das ninfas virarem adultas.
Os machos dessa família produzem sons, geralmente à noite, a fim de atrair fêmeas para cópula, quando suas asas anteriores (tégminas) fecham e as estruturas especializadas presentes nessas asas atritam entre si. Essas estruturas são as fileiras de pequenos dentes ou dentículos (saliências triangulares na superfície inferior da veia pós-cubital), presente na tégmina direita e o plectrum (área esclerotizada na região anal), presente na tégmina esquerda. Os sons produzidos são geralmente muito altos (grande amplitude) e de longa duração (algumas espécies são sensíveis até ao ultrassom). Além disso, os sinais tornam-se mais potentes e atingem maiores distâncias por conta da construção das tocas de canto, onde as asas são posicionadas entre o bulbo e a câmara de entrada (com a cabeça do inseto dentro do bulbo) durante a produção de som, para que haja a ampliação.
Os grilos-toupeira podem ser herbívoros ou predadores e são capazes de causar grandes danos a vegetações, seja por escavação de túneis nas raízes ou por se alimentarem diretamente de todas as partes das plantas. O controle desses insetos é difícil, pois vivem enterrados no solo, são móveis e, portanto, menos propensos a entrar em contato com inseticidas. Além disso, fatores como umidade e temperatura do solo, condições climáticas, comportamento e estágio do desenvolvimento podem variar a eficácia dos esforços de controle. Por isso, há a necessidade de um alto uso de inseticidas em plantações e campos de golfe, o que torna o custo financeiro e ambiental do controle das paquinhas muito alto. Portanto, conhecer a biologia desses animais é de extrema importância econômica, agrícola, urbana e ambiental.
Armadilhas luminosas são eficazes para ambos os sexos. Armadilhas acústicas com o uso de playbacks dos machos são eficazes para a atração das fêmeas. Entretanto, esses métodos são capazes de coletar somente indivíduos que possuem capacidade de voar.[18]
Gryllotalpidae trata-se de uma pequena família monofilética, da ordem dos ortópteros (gafanhotos, esperanças e grilos), que contempla mais de 100 espécies distribuídas em três subfamílias (duas existentes e uma fóssil) e que, provavelmente, surgiu entre o final do Jurássico e o início do Cretáceo. A história taxonômica do grupo começa quando Linnaeus (1758) descreveu a espécie Gryllus (Acheta) gryllotalpa. Em 1802, Lattreille descreveu o gênero Gryllotalpa, transferindo a espécie de Linnaeus para status de gênero. Somente em 1815, Leach estabeleceu a família Gryllotalpidae, incluindo a espécie Gryllotalpa gryllotalpa.
São insetos mundialmente distribuídos, exceto nas regiões polares. A maioria de suas espécies ocorre em zonas tropicais e alguns em zonas temperadas. Nesta família estão inclusos alguns dos ortópteros mais distintos, por possuírem pernas dianteiras bem desenvolvidas utilizadas para cavar túneis e galerias profundas no solo, onde se abrigam e acessam as raízes das plantas, onde se alimentam. Por isso, se tornaram importantes pragas de gramíneas, plantações e campos de golfe. Os danos são de forma direta e indireta. Sendo direto por conta de cortar o caule e se alimentar das raízes, e indiretamente devido as galerias que afetam diretamente a germinação das sementes. São ativos durante a noite e os machos adultos são capazes de produzir sons bem altos.
As espécies desta família são conhecidas popularmente pelos nomes de ralo (Portugal), paquinha (Brasil), cachorro-d'água, cachorrinho-da-terra, grilo-toupeira, grilotalpa, entre outros.
땅강아지과(Gryllotalpidae)는 메뚜기목에 딸린 곤충의 한 과이다. 메뚜기목 중 땅속을 파 생활하는 것으로 알려져 있다. 세계 각지에 분포하고 있으며, 그 중 열대·온대 지방에 많은 종이 살고 있다. 대한민국에 서식하는 종은 땅강아지(Gryllotalpa orientalis)이다.
성충은 30mm ~ 40mm 정도의 크기이다. 몸은 다갈색이며 노란빛갈의 잔털이 나있다. 두부와 앞가슴부위는 계란형으로 뒤가슴부와 복부는 앞가슴부위보다 폭이 좁다. 몸끝부분에는 긴 꼬리가 2개 나있다.
성충에는 날개가 있으며, 길이는 종류와 개체에 따라 다르다. 대개 앞날개가 짧고, 뒷날개가 길다. 수컷은 귀뚜라미와 같이 앞날개의 날개 맥이 복잡한 발성기관을 가지고 있지만, 암컷의 경우 날개의 맥이 단순해 수컷에 비해 발성이 적다. 날기도 한다. 그러나 주로 걸어다니며, 밤에 종종 불빛에 날아들기도 한다.
초원과 논밭에 서식하며, 땅을 파 땅속에서 생활한다. 건조하고 딱딱한 지면보다는 습기가 있는 진흙이나 습지가 보다 서식처로 좋다. 성충과 유충모두 식성은 잡식성으로 식물의 뿌리나 씨앗, 그 밖에 소곤충과 지렁이 등을 먹고 자란다.
산란은 보금자리의 구멍 깊숙한 곳, 진흙으로 만든 고치와 같은 곳에 하며, 산란후 밀폐해 주변을 지킨다. 유충은 성충과 달리 날개가 없을 뿐 성충과 생김새가 같다. 얼마간 집단생활 후 어미곁을 떠나 생활한다.
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