What Bug Is That? The guide to Australian insect families.

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Acrididae

Overview

This is the largest family of Caelifera. The species exhibit little of the specialisation seen in the other acridoid groups. Dirsh (1961) recognised 17 subfamilies, including 6 from Australia; only 4 of the latter are currently recognised. No representatives of the sound-producing Gomphocerinae, which are common in the Northern Hemisphere, occur in Australia. At the generic level there is 90% endemicity. The most common chromosome number throughout the world is 2n [male] = 23 but numbers as low as 8 are known.

Chromosomal studies have been made of Austroicetes interioris (Nankivell 1967), Goniaea australasiae (Peacock 1970) and a gynandromorph Valanga irregularis (White 1968). For the Caledia captiva complex Shaw and Wilkinson (1980) have studied chromosome differentiation and population genetics, and Daly et al. (1980) the distribution of allozymic variation in relation to reproductive isolation. Peters (1981) studied polysomy in Atractomorpha similis .

Distribution

The Oxyinae include 12 genera of Indo-Malayan origin. Many are associated with water and grasslands. Oxya japonica , one of the most destructive grasshoppers in rice fields in South-East Asia, also occurs in Australia where it does minimal damage. Bermiella acuta which occurs on sedges, rushes and grasses near water, has a number of adaptations for semiaquatic life, such as dense patches of hairs on the distal abdominal sterna and tegmina and an air chamber formed by the doming of the costal area of the tegmen over the 1st abdominal spiracle. John and Freeman (1976) have studied the chromosome systems of 3 species of the tropical and subtropical oxyine Tolgadia .

The spur-throated grasshoppers of the Catanotopinae comprise 84% of the Australian acridoid fauna. This is a disparate percentage when compared with other regions of the world. Goniaea is a typical example with species living among fallen leaves under eucalypts. Their cryptic colouration and the leaf-like shape of nymphs render them invisible until they move. Coryphistes is found on tree trunks, dead branches and leaf litter where it is also cryptically concealed. Ecphantus quadrilobus is velvety green or light brown and seems restricted to plants of the genus Sida .

Of all the grasshoppers only one genus, Phaulacridium , is shared with New Zealand. P. vittatum , the wingless grasshopper , is predominantly brachypterous but macropters become more numerous as population densities increase (Nicolas et al. 1982). It is of economic importance because of the damage it does to pastures (see Clark 1962; Farrow 1982c). Dearn (1984 for refs.) has studied colour pattern polymorphism in this species as it relates to habitat and distribution, as well as the influence of inheritance and natural selection in maintaining pattern polymorphism. Raniliella has an enlarged pronotum with dorsal tubercles which help to conceal it on stony substrates. Urnisiella rubropunctata has very long mid legs which it uses to bury itself in sand at dusk.

The large spur-throated grasshoppers of the Cyrtacanthacridinae are represented by large, mostly tropical species. Some of the world's most important locust pests are in this subfamily. Both Australian genera, Nomadacris and Valanga , have Malayan and Pacific distributions. Nomadacris guttulosa (formerly Austracris ), the spur-throated locust, is found all over Australia although it is primarily adapted to tropical grasslands in which the adults overwinter in reproductive diapause often roosting in trees and shrubs. Maturation and oviposition at the onset of the rains of summer has been studied by Farrow (1977a). Plagues originate from these grasslands and may damage both dicotyledonous and monocotyledonous summer crops (Elder et al. 1979; Casimir and Edge 1979).

One of the world's largest acridoids is Valanga irregularis , a species of the Tropics and Subtropics, feeds on leaves of trees and shrubs and can cause some damage to fruit and nut trees.

The Acridinae is a large group with world-wide distribution. Several locusts are included. This group contains some of the most phylogenetically advanced grasshoppers with 22 genera and 33 species known from Australia. About one-third of this total is contributed by Old World genera. For example, Acrida , Gastrimargus and Sphingonotus , are represented in Australia by single species. Chortoicetes terminifera is the most important Australian locust pest; it is characterised by a black spot at the tip of the hind wing (see Key 1958; Casimir 1962).

Other important contributions concerning this species are as follows: on the frequencies and inheritance of pattern morphs (Byrne 1967); on the protein and amino acid content of the haemolymph in relation to diet and hydration (Djajakusumah and Miles 1966; Muljadi 1967), on egg development in relation to temperature and moisture, with reference to the induction of diapause (Wardhaugh 1972; Gregg 1983; Hunter and Gregg 1984); on flight, the factors initiating it, and its significance in migration (D.P. Clark 1969, 1971; Drake and Farrow 1984; Hunter et al. 1981); on plague dynamics and field ecology (L.R. Clark 1947; D.P. Clark 1972; D.P. Clark et al. 1969; Farrow 1977a,b,c; Farrow and Longstaff 1987; Key 1954; Symmons and Wright 1981; Wright and Symmons 1987); and, finally, on population dynamics (D.P. Clark 1974, 1978; Farrow 1979, 1982a, 1982b).

One of the most important Old World locust pests, Locusta migratoria migratorioides is widely distributed in coastal and sub-coastal grasslands but only one plague has broken out to date; this occurred between 1973 and 1976 (Elder et al. 1979). The Australian population is identical to the tropical race of this locust (Farrow and Colless 1980). Sound production by males is well developed in this family and varies from stridulation by the hind femora in Schizobothrus flavovittatus , to wing clicking in Gastrimargus musicus and L. m. migratorioides , and the wing buzzing produced by Froggatina australis , in flight. [Ritchie 1982; Vickery 1977.]

  • Chortoicetes terminifera (Australian plague locust)

  • Coryphistes ruricola

  • Acrididae

  • Goniaea sp.

  • Perala sp.

  • Raniliella sp.

  • Bermioides nigrobivittatus

  • Acrida conica

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