Literature review: Impact of Chilean needle grass ... - Weeds Australia

eing sluggish and wingless, and exist, or once existed, in numerous small sub-populations (Key 1978). Conservation of many of
the remnant populations as possible is desirable because of their large genetic and chromosomal variation.
Three species of Morabinae are known from areas of grassland in south-eastern Australia. Vandiemenella viatica (Erichson), the
first morabine grasshopper described, occurs from south-eastern Tasmania and King Island through south and west Gippsland
and western Victoria to Kangaroo Island, and has 19 and 17 chromosome races, the former present in Victoria and Tasmania
(Key 1976 1981). Vandiemenella species are dicotyledon feeders (Key 1976). The genus has been the subject of the most
comprehensive studies of parapatry in the Morabinae. Twelve species or races have been distinguished based on karyotype, male
cercus and genitalia characters, and size relationships (Key 1981 p. 433). Natural hybrids between the chromosome race of V.
viatica with an estimated fertility depression of only c. 10%, occur in the contact zone in South Australia. Hybridisation
experiments with the various Vandiemenella races and species have found no evidence that offspring males are completely
sterile (Key 1981).
Keyacris Rehn contains c. 10 species that occur on forbs and low shrubs in south-eastern Australia through southern South
Australia to south-east coastal Western Australia (Key 1976). Keyacris scurra (Rehn), Key’s matchstick, is found on the
tablelands of southern NSW and the ACT (Key 1981, Rowell and Crawford 1995) in grassland and grassy woodland (Driscoll
1994), and was considered by Key (1978) to be the second most threatened morabine. New (2000) listed it as one of few flagship
invertebrate taxa for Australian temperate grassland. It was previously found over a large area of south-eastern NSW, the ACT
and Victoria but its range has severely contracted due to destruction of habitat, including grazing and other disturbances (Rowell
and Crawford 1995). It is a small species about 25 mm long with form and colouring that makes it difficult to distinguish from
dry grass and litter (Driscoll 1994). It is “dependent for its survival” upon stands of T. triandra and associated forbs, is
eliminated, “along with its habitat”, under intensive sheep grazing, and is now largely restricted to country cemetry reserves
(Key 1978 p. 7), fenced areas along railway lines, and some paddocks only ever grazed by cattle or horses (Key 1981). Rowell
and Crawford (1995) surveyed 700 ha of potentially suitable habitat in the northern ACT in 1994 and found populations at 7 sites
with widely varying management histories, with a total area of 25 ha, and along the Queanbeyan to Williamsdale rail easement
in adjacent areas of NSW. Colonies occupied areas from 0.1 ha to 20 ha. They also reported on an unconfirmed site in Namadgi
National Park in the southern ACT. Three populations were new records, and two previously known populations were found to
be extinct. Its presence was correlated with that of 14 uncommon to endangered plants, also threatened by grazing and with
Delma impar. Sharp and Shorthouse (1996) mentioned a then current study to determine the effects of vegetation composition
and past management on populations. Farrow (1999) recorded its presence at one ACT grassland.
K. scurra is a winter grasshopper with a single generation per year, hatching in February and reaching maturity by May (males)
or in spring. It has very low fecundity: a maximum of 21 eggs was produced by a female in a laboratory colony. The eggs are
deposited shallowly in surface soil (Rowell and Crawford 1995).
T. triandra is used for shelter and perennial Asteraceae “usually a species of Helichrysum” are eaten (Key 1981 p. 432).
“Helichrysum” is an old portmanteau name, subsequently split into numerous genera. Driscoll (1994) stated that the preferred
food plants are Chrysocephalum semipapposum and C. apiculatum, the former also being used for shelter. The actual diet may be
much more diverse, since individuals ate a wide range of native and exotic herbs and shrubs when offerred no other food (Rowell
andCrawford 1995, citing Blackith and Blackith 1966). Rowell and Crawford (1995) distinguished three inhabited plant
assemblages: Chrysocephalum semipapposum woodland and wet and dry T. triandra grasslands sometimes with derived origins.
Dense T. triandra was not suitable habitat. Other native daisies in the tribe Inulae were suspected to be the food plant in areas
where Chrysocephalum was absent.
K. scurra has two races, with 15 and 17 chromosomes respectively, which are believed to have once been in contact over a
distance ofabout 200 km, but by the late 1950s were much depleted, although a 16 chromosome hybid individual, with an
estimated reduction in fertility of 10% was detected in a relict of the contact zone. An artificial field population consisting of
males of one race and females of the other survived for at least four generations (Key 1981). Rowell and Crawford (1995)
provided additional details of populations, colouration, behaviour and habitat of K. scurra and discussed threatening factors.
These include exotic grass invasion (namely Nassella trichotoma, Anthoxanthum odoratum, Eragrostis curvula and Holcus
lanatus), increased cover of T. triandra, grazing and changed fire regimes.
Achurimima Key contains 17 species found in the herbaceous stratum or on low shrubs, very irregularly in the southern two
thirds of inland Australia (Key 1976). Achurimima sp. P42, appears to be the most threatened morabine, recorded from only 6
localities in south-eastern NSW “where small populations survive on lightly grazed native pastures including the composite
Helichrysum semipapposum” (Key 1978 p. 18) (now Chrysocephalum semipapposum). Driscoll (1994) noted that efforts by the
NSW National Parks and Wildlife Service to reserve an area where this species was present along with K. scurra were frustrated
by an uncooperative landholder.
Replacement of forb-rich T. triandra grassland by Austrostipa-Austrodanthonia pasture due to sheep grazing on the southern
tablelands of NSW produced “a complete change in the grasshopper fauna”, including the loss of two species which became
restricted to cemetries (Key 1978).
Canberra raspy cricket Coorabooraama canberrae Rentz
C. canberrae (Orthoptera: Gryllacrididae) is a very large cricket, with a body about 40 mm long and antennae of twice this
length, recorded only from urban areas in Canberra. The genus is monospecific (Rentz 1996). No populations were known in
1994 (Driscoll 1994). It probably lives under bark and litter and is found in suburban gardens (Driscoll 1994). Rentz (1996)
considered it likely to be a grassland species. Virtually nothing is known about its biology. Farrow (1999) collected an
unidentifed first instar gryllacridid at the Majura grassland in the ACT and noted that adults are known to occur there. Rentz
(1996) provided a colour photograph of a male. Gryllacridids are predatory and often have highly specific food preferences.
They all stridulate and are nocturnal, spending the day in burrows or leaf shelters they construct using silk from the mouthparts
(Rentz 1996).
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