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

found in all mainland states, O. compositus is not known from Victoria or NSW. Other Pseudonampomyza spp. with angulate
third antennal segments have host plants restricted to Poaceae, but no known Australian hosts: P. probata Spencer, P. rara
Spencer, P. salubris Spencer and P. pudica Spencer. Agromyza mellita Spencer and A. venusta, both known from northern
Queensland have male genitalia with “the characteristic form of grass-feeders” (Spencer 1977 p. 122).
Some Anthomyiidae (Diptera) also attack grasses including the wheat bulb fly Delia coarctata (Fallén), D. extreminata
(Malloch) in Bromus in the USA, and Phorbia spp. mining stems and shoots (Ferrar 1987). Others are known to breed on
Epichloe fungi on grasses (Ferrar 1987).
Larvae of numerous Chloropidae species live in young shoots and stems of grasses and may feed largely on bacteria (Colless and
McAlpine 1991) or be saprophagous rather than phytophagous (Ferrar 1987), however little is known of the biology of
Australian species (Sabrosky 1989). Ferrar (1987) provided summary information on some pests of cereals and pasture grasses
elsewhere in the world, plus a tabulation of the genera known from Poaceae. Most Chloropinae attack Poaceae or Cyperaceae, as
do some Oscinellinae (Ferrar 1987). Some Oscinella species appear to be monophagous on particular grass species, while others
have multiple known grass hosts (Ferrar 1987). Thirty-two Chloropidae spp., mostly endophages, have been collected from
Phragmites, over 20 of which are monophagous (Witt and McConnachie 2004). Diplotaxa similis Spencer has been commonly
found in the florets of Chionochloa spp. in New Zealand and has been viewed as the major seed predator, although they may
actually often destroy the flower before seed formation, and there has been considerable confusion about whether the damage is
caused by the chlropopid or Cecidomyiidae (Kelly et al. 1992). The wingless D. moorei (Salmon) Spencer is a predator of
Festuca novae-zelandiae author (Kelly et al. 1992).
Some Ephydridae, mostly Hydrellini, attack grasses, and some are cereal pests, but most breed in aquatic situations or wet areas
and feed on decaying matter, algae etc. (Ferrar 1987). Hydrellia spp. are recorded from Lolium, Poa, Pennisetum, Holcus,
Panicum, Echinochloa and other grasses outside Australia (Ferrar 1987)
Hemiptera
Hemiptera also appear to have good representation on grasses. Specialist insects on Spartina alternifolia are mainly Hemiptera
(Witt and McConnachie 2004). Among the Heteroptera, the Leptocorisini (Alydidae: Leptocorisinae) is closely associated with
grasses and includes a number of rice pests, while the Stenodernini (Miridae) and Blissinae (Lygaeidae) are also grass
inhabitants (Ahmad 1965). Lygaeids are mostly seed eaters but the Blissinae (Chinch Bugs) feed on grass sap (Slater 1991).
Subfamily Cyminae of Lygaeidae contains “small, brown bugs that live in seed heads and resemble seeds of various sedges and
rushes” (Slater 1991 p. 502) and possibly includes some grass feeders. The pachygronthine Stenophyella macreta Horváth “is
often common in seed heads of grasses” (Slater 1991 p. 502) and “appears to feed on a number of grasses even when they are
completely dry” (Slater 1976 p. 135). Nabidae are predacious but oviposit in grass stems (Gross and Cassis 1991). Many grassfeeding
Homoptera have a narrow host range, but mealybugs Pseudococcidae and soft scales Coccidae are generally
polyphagous (Witt and McConnachie 2004).
Farrow (1999) found that Cicadellidae (leafhoppers) were very numerous in grasslands in the Australian Capital Territory and
this family along with other planthoppers (Delphacidae, Eurymelidae, Flatidae, Membracidae, Ricanidae), froghoppers
(Cercopidae), cicadas (Cicadidae) and allies, collectively classified in the suborder Auchenorryhncha, has been identified as a
highly appropriate higher taxon for evaluation of the conservation significance of grasslands and monitoring environmental and
habitat change, at least in Europe (Biedermann et al. 2005). They are diverse, with many rare species, wholy herbivorous, their
numerical abundance supports higher trophic levels, and perhaps most importantly, rhey have high and rapid sensitivity to a
range of disturbances (Biedermann et al. 2005). The European grassland fauna however is much better described than that of
Australia, baseline studies of whole faunas have been undertaken and some effects of grassland management on the faunas have
been determined.
Poaceae probably supports a higher diversity of Australian cicadas (Cicadidae) than any other plant family, but few species
inhabit the grasslands of the south-east (Moulds 1990). Nymphs of the grass-feeding species feed on grass roots, and the adults
of some species oviposit in grass stems or leaves (Moulds 1990). Evans (1966) considered the cicadelloid fauna of Australian
grasses and herbs to be depauperate and Australian grasslands to carry “a very small leafhopper population and ... even fewer
cercopids” (p. 20) in comparison with other parts of the world. However Day and Fletcher (1994 p. 1119) noted that there had
been “little systematic collecting” of Cicadelloidea in Australia and that distribution data was “very inadequate”. According to
Evans (1966 p. 21) both Cicadelloidea and Cercopoidea were “not usually abundant on grasses” in Australia, and most grassfrequenting
species were introduced, but he acknowledged that records of food plants were very scanty. However Evans (1966 p.
133) thought it “probable” that all species of Hecalini (Cicadellidae) are grass-feeders. Hecaleus arcuatus (Motschulsky) known
from Queensland and outside Australia is recorded from T. triandra and Heteropogon (Day and Fletcher 1994). Day and Fletcher
(1994) listed numerous species with known grass hosts in Australia but their designation of “host” is not rigorous; e.g. Evans
(1966) stated that Mircrolopa minuta Evans was collected on grasses, which became in Day and Fletcher (1994 p. 1123):
“Known hosts: Poaceae (Evans 1966: 87)”. Their host information “frequently reflects the plant species on which specimens
were colleced and do not necessarily reflect the true hosts” (Day and Fletcher 1994 p. 1121).
Hymenoptera
Many ‘seed chalcids’ Eurytomidae (Hymenoptera) are host specific and different species develop in different positions within
the culm (Witt and McConnachie 2004). They can cause major reductions in forage yield and seed weight, including a reduction
of 60% in Heterostipa comata (Trin. and Rupr.) Barkworth, with consequent reduction in germinability (Witt and McConnachie
2004). A Tetramesa sp. in Africa that bores in the stems of Sporobolus spp. was found to infest 33% of culms at one site.
Infested culms were significantly shorter than uninfested and 60% had deformed infloresences (Witt and McConnachie 2004).
The tribe Cephini of the sawfly family Cephidae consists of grass-mining specialists, a number of which are cereal pests, but is
restricted to the Nearctic and Holarctic (Ivie 2001).
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