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

Lepidoptera
Amongst the Lepidoptera that attack Poaceae, the Noctuidae are generally polyphagous (Witt and McConnachie 2004). A high
proportion of Satyrinae (Nymphalidae) and Hesperiidae are grass feeders (Braby 2000). A study of 13 satyrines and 3 hesperines
showed that they all stored the grass secondary metabolite flavonoid tricin, while one species stored glycosylflavones, with the
flavone stored in the wings and body and constituting 1-2% of their dry weight.(Harborne and Williams 1986). One important
role of flavonoids in grasses is probably as grazing deterrents (Harborne and Williams 1986) and these butterflies have therefore
to some extent overcome those defences. A species of Gelechiidae has been found rarely attacking the florets of Chionochloa
spp. in New Zealand (Kelly et al. 1992).
Australian Grassland Invertebrate Faunas
A few studies of the faunas of particular natural grassland associations have been undertaken in Australia including Sharp
(1997), Melbourne (1993), Farrow (1999 2006), New (2000), Gibson and New (2007) and the studies of Yen and colleagues in
Victoria. The study of Farrow (1999) was a pioneering quantification of the biodiversity of a major part of the insect fauna of
ACT grasslands.
Victoria
Terrestrial invertebrates of western Victorian Basalt Plains Grasslands have been surveyed and discussed by Yen (1999) and
assessed by Yen, Horne, Kay and Kobelt (1994) and Yen et al. (1995), and in the western region of Melbourne by Yen, Kobelt,
Lillywhite and Van Praagh (1994). These were the first baseline invertebrate surveys of native temperate grasslands in southeastern
Australia (Farrow 1999), however these are long unpublished reports containing little analysis. Previous studies covered
only a very limited number of individual taxa (e.g. Key 1978, Horne 1992, McDougall 1989), or were a part of dietary studies of
endangered vertebrates including Delma impar (Coulson 1990, Wainer 1992) and Perameles gunnii (Yen 1995) or related to
agricultural pest species (e.g. Schroder 1983). Approximately 50 taxa were identified from pitfall trap specimens taken at
Derrimut Grassland Reserve by Kathy Ebert (Coulson 1990) but only ants and some spiders were identified, and only to genus.
Initial pitfall trap sampling suggested that basalt plains grasslands have lower invertebrate divesity than other habitats in Victoria
(Yen 1999), paralleling Willis’s (1964) view of the vascular plant and bryophyte diversity.
Hadden (1997, 1998) investigated invertebrates in both the Northern and Western Plains, but did not provide specific
identifications. Hadden and Westbrooke (1999) detected 160 arthropod morphospecies using pitfall traps, sweep net and hand
searching in a grazed T. triandra pasture near Ballarat: 26 Formicidae, 90 Coleoptera and 44 Araneae. The Coleoptera and
Araneae were identified to family level and the Formicidae to genus. Various features of the fauna were identified including the
low number of aerial web-building spiders, the dominance of Iridiomyrmex spp. ants and the small size of those Coleoptera spp.
that were abundant. Gibson and New (2007) detected 24 morphospecies of Formicidae and 27 Coleoptera species by pitfall
trapping in spring and summer at Craigieburn grassland, Victoria. Both major taxa appeared to be representative of regional
diversity and included no rare or apparently grassland-specific species.
Collecting techniques used in the surveys of Yen et al. were pitfall trapping, weeping, suction sampling, canopy fogging and
direct searching. Yen, Horne, Kay and Kobelt (1994) reported on 1992-3 seasonal surveys of 12 remant grassland sites
representative of the range of site types, management practices and conservation ranking of all sites previously listed McDougall
and Kirkpatrick (1994): 5 roadside reserves (4 burnt annually), 3 railway reserves (2 burnt annually), 2 privately owned pastures,
1 conservation reserve and 1 cemetry; and an additional 5 sites were surveyed once: 2 rail, 1 roadside, 2 private, along with 6
areas adjacent to seasonally sampled sites. Yen, Kobelt, Lillywhite and Van Praagh (1994) surveyed a variety of vegetation types
during 1991-93 that included 2 Poa grasslands (Point Cook and Werribee) and 5 T. triandra grasslands (Truganina, Derrimut, St
Albans rail reserve, Manor rail reserve, Evan St rail reserve). Yen et al. (1995) surveyed 29 additional grassland sites during
1994, completing their coverage of all the remnant grasslands listed by McDougall and Kirkpatrick (1994) that were still in
existence. 5 of these sites were in the Melbourne region and the remainder between Ballarat and Hamilton.
Yen, Kobelt, Lillywhite and Van Praagh (1994) quantified the numbers of individuals collected by order, and by genus or
species (where possible) for Coleoptera (beetles), Formicidae (ants) and Araneae (spiders). Yen, Horne, Kay and Kobelt (1994)
and Yen et al. (1995) duplicated this analysis but also included species or genus level data for Orthoptera (grasshoppers and
crickets) and Hemiptera (true bugs) and reported on spiders only at family level.
A reference collection of grassland invertebrates has been established at the Museum of Victoria under the supervision of Peter
Lillywhite, and identification of included taxa is proceeding gradually (Yen pers. comm. 2006, Kobelt pers. comm. 2007).
Miller and New (1997) determined the ant fauna of (?derived) Austrodanthonia grasslands at Mount Piper, Victoria. The fauna
was a far less diverse subset of that found in nearbye woodland and only one species was restricted to grassland. They found that
sites invaded by Holcus lanatus supported an average of c. 16 and a total of 28 morphospecies while the more natural grasslands
supported an average of c. 21 and a total of 33 morphospecies. However matched invaded and uninvaded sites”only a few tens of
metres apart, did not differ significantly from each other in diversity” (p. 378) and “many species” showed “little apparent
discrimination in relation to dominant grass species” (p. 381). Four morphospecies were trapped only at H. lanatus sites, while
seven were trapped only at the Austrodanthonia sites. “Overall disturbance may be more significant to ants than simple
replacement of native by exotic grass species” (Miller and New 1997 p. 381).
Few unique features have been noted about Victorian grassland invertebrate assemblages. One such example is the presence of
ants that make use of rocks as a habitat. These ants are absent from ACT grasslands (Melbourne 1993).
Australian Capital Territory
Little is known about the distribution and ecological requirements of most invertebrate species in ACT grasslands (Sharp 1997 p.
4), although the fauna is much better studied that most other grassland areas, partly due to the presence of CSIRO Entomology
and its predecessors in the national capital since 1928. Driscoll (1994) integrated knowledge then available to develop an
invertebrate conservation and research strategy for the ACT. Numerous localised studies of selected grassland groups or species
have been undertaken, including Edwards (1994) on the Golden Sun Moth, Rowell and Russell (1995) on the grasshopper
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