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