Orthoptera

Introduction

The more than 20,000 species in this order have a worldwide distribution but are most diverse in the tropics. Body size varies from less than 5 mm to some of the world's largest insects, with body lengths up to 11.5 cm, and wingspans of over 22 cm. Orthopterans are a common component of terrestrial insect faunas and include some of the most voracious pests (locusts and certain katydids). Members of both suborders are generally phytophagous but many species are omnivores. Females of most species lay clutches of eggs, either in the ground or in vegetation. Some of the best examples of cryptic coloration are seen in this group, involving mimicry of leaves and other vegetation or other resemblance to the background (Chopard 1938; Hewitt 1979; Kevan 1982; Rentz 1991). Grasshoppers, katydids and crickets are well known for their abilities to jump and particularly for singing by males (females are typically silent). There are few places in the world where the calls of grasshoppers (usually diurnal), katydids and crickets (usually nocturnal) cannot be heard during warm seasons. Organs of sound production and sound reception involve quite different body parts in the two subgroups (Alexander 1960; Dumortier 1963).

The first fossil Orthoptera appear in the upper Carboniferous with the first Ensifera (Chopard 1920) appearing in the Permian and the first Caelifera (Ander 1939) in the Triassic (Gorochov 1995; Kukalova-Peck 1991; Sharov 1968; Zeuner 1939). The two groups are usually considered suborders of the Orthoptera. Attempts to create a separate order for the two suborders Caelifera and Ensifera (e.g. Kevan 1986, in which Ensifera = Grylloptera) have not found general entomological acceptance (see Discussion of Phylogenetic Relationships).

Characteristics

The name Orthoptera is derived from "orthos" meaning "straight" and "pteron" = "wing."

Shared-derived characters: in addition to the saltatory hind legs, most orthopterans have small and well separated hind coxae, a pronotum with large descending lateral lobes, nymphal wing rudiments reversing their orientation in later instars and hind tibiae with two dorsal teeth rows (Kevan 1982; Kukalova-Peck 1991; Rentz 1991). Other characteristics are unsegmented cerci and leathery forewings.

Discussion of Phylogenetic Relationships

General opinion favors a monophyly hypothesis for the order Orthoptera (Hennig 1981; Gorochov 1995). Most studies have examined extant taxa. Although numerical analyses of orthopteroid character distributions (mainly phenetic) by Blackith (1968) show the Blattodea-Mantodea clade and not Caelifera as the sister group of Ensifera, Kamp's (1973) analysis of a more expanded morphological character matrix supports monophyly. Kristensen's (1991) discussion also supports monophyly. Formal analyses of molecular characters (Flook and Rowell 1997) also support the conventional view of a unitary order Orthoptera. For discussions that include extinct taxa, Kukalova Peck (1991) suggests the group may not be monophyletic but Gorokhov (1995) supports monophyly. A sister group relationship between Ensifera and Phasmatodea has been proposed (Sharov 1968), but this is inconclusively supported according to Kristensen (1995) who suggested that the characters involved (wing venation) are not synapomorphies. Molecular data show a unitary Orthoptera as the sister group of a clade comprising the Phasmida and the Embiidina (Flook and Rowell 1998, Flook et al. 1999). Trees of extinct and extant Orthoptera (Sharov 1968; Zeuner 1939) show Caelifera as derived from a primitive ensiferan stock (not more recently than the Permo - Triassic boundary). However both authors show all extant groups as monophyletic. This interpretation is consistent with the numerical analyses of morphological characters in orthopteroid insects (Blackith and Blackith 1968; Kamp 1973), a recent review of the phylogeny of extant hexapods (Kristensen 1991), and molecular sequence data (Flook and Rowell 1998, 1999, non-technically reviewed by Rowell and Flook 1998).

Other Names for Orthoptera

• orthopterans
• Crickets, katydids, grasshoppers, etc.

References

Alexander, R.D. 1960. Sound communication in Orthoptera and Cicadidae. In: Animal Sounds and Communication (Eds. W. E. Lanyon and W. N. Tavolga), Amer. Instit. Biol. Sci. No.7., Washington, D.C.:38-92.

Ander, K. 1939. Comparative anatomical and phylogenetic studies on the Ensifera (Saltatoria). Opusc. Entomol. Suppl. II. Lund.

Blackith, R.E., and R.M. Blackith. 1968. A numerical taxonomy of orthopteroid insects. Aust. J. Zool. 16:111-131.

Chopard, L. 1920. Recherches sur la conformation et la développement des derniers segmentes abdominaux des Orthoptères. Thèse, Faculté des Sciences de Paris, Oberthur, Rennes.

Chopard, L. 1938. La biologie des Orthoptères. Encycl. ent. Ser. A 20:iV:1-541.

Dumortier, B. 1963. The physical characteristics of sound emissions in Arthropoda. In: Acoustic Behaviour in Animals (edited by R.-G. Busnel). Amsterdam: Elsevier.

Flook, P. K. & Rowell, C. H. F. 1997. The phylogeny of the Caelifera (Insecta, Orthoptera) as deduced from mitochondrial rRNA gene sequences. Molecular Phylogenetics & Evolution 8: 89-103.

Flook, P. K. & Rowell, C. H. F. 1998. Inferences about orthopteroid phylogeny and molecular evolution from small subunit nuclear ribosomal RNA sequences. Insect Mol. Biol. 7: 163-178.

Flook, P. K. Klee, S., & Rowell, C. H. F. 1999. A combined molecular phylogenetic analysis of the Orthoptera and its implications for their higher systematics. Syst. Biol. 48: 233-253.

Gorochov, A. V. 1995. Contribution to the system and evolution of the order Orthoptera. Zoologichesky Zhurnal 74:39-45.

Hennig, W. 1981. Insect Phylogeny. Chichester: John Wiley and Sons.

Hewitt, G.M. 1979. 1979. Orthoptera: grasshoppers and crickets. Berlin: Gerbruder Borntrager.

Kamp, J.W. 1973. Numerical classification of the Orthopteroids, with special reference to the Grylloblattodea. Can. Entomol. 105:1235-1249.

Kevan, D.K. McE. 1982. Orthoptera. In: Synopsis and Classification of Living Organisms (edited by S. P. Parker). New York: McGraw Hill.

Kevan, D.K. McE. 1986. A rational for the classification of orthopteroid insects - the saltatorial orthopteroids or grigs - one order or two? Proceedings of the Pan American Acridological Society 1985:49-67.

Kristensen, N.P. 1991. Phylogeny of extant hexapods. In: The Insects of Australia (edited by CSIRO). Melbourne: Melbourne University Press.

Kristensen, N.P. 1995. Forty-years' insects phylogenetic systematics. Zool. Beitr. N.F. 36:83-124.

Kukalova-Peck, J. 1991. Fossil history and the evolution of hexapod structures. In: The Insects of Australia (edited by CSIRO). Melbourne: Melbourne University Press.

Rentz, D.C.F. 1991. Orthoptera. In: Insects of Australia (edited by CSIRO). Melbourne: Melbourne University Press.

Rowell C.H.F. and P.K. Flook. 1998. Phylogeny of the Caelifera and the Orthoptera as derived from ribosomal RNA gene sequences. J. Orthopt. Res. 7: 147-156.

Sharov, A.G. 1968. Phylogeny of the Orthopteroidea. Trans. Paleontol. Instit. Acad. Sci. 118:1-216.

Zeuner, F.E. 1939. Fossil Orthoptera Ensifera. London: British Museum Natural History.

Information on the Internet

• Orthopterist's society homepage
• Orthoptera del Noreste amazónico
• The Orthoptera Species File Online (a taxonomic database of the world's orthopteroid insects)
• Orthoptera Photovault.
• Orthoptera. Australian Museum.
• Orthoptera of the Northern Great Plains.
• Singing Insects of North America.
• Checklist of Turkish Orthoptera.