Australian Plague Locust
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The Australian plague locust (''Chortoicetes terminifera'') is a species of
locust Locusts (derived from the Latin ''locusta'', locust or lobster) are various species of short-horned grasshoppers in the family Acrididae that have a swarming phase. These insects are usually solitary, but under certain circumstances they b ...
in the family
Acrididae Acrididae are the predominant family of grasshoppers, comprising some 10,000 of the 11,000 species of the entire suborder Caelifera. The Acrididae are best known because all locusts (swarming grasshoppers) are of the Acrididae. The subfamily Oedi ...
native to
Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
, where it is a significant
agricultural pest A pest is any organism harmful to humans or human concerns. The term is particularly used for creatures that damage crops, livestock, and forestry or cause a nuisance to people, especially in their homes. Humans have modified the environment fo ...
. Adult Australian plague locusts range in size from 20 to 45 mm in length, and the colour varies from brown to green. In profile, the head is higher than the
thorax The thorax (: thoraces or thoraxes) or chest is a part of the anatomy of mammals and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main di ...
, and the thorax has an X-shaped mark. The legs have a reddish shank and the wings are clear other than for a dark spot on the periphery.


Range and habitat

The locusts occur naturally in far northwestern
New South Wales New South Wales (commonly abbreviated as NSW) is a States and territories of Australia, state on the Eastern states of Australia, east coast of :Australia. It borders Queensland to the north, Victoria (state), Victoria to the south, and South ...
and the adjoining areas of
Queensland Queensland ( , commonly abbreviated as Qld) is a States and territories of Australia, state in northeastern Australia, and is the second-largest and third-most populous state in Australia. It is bordered by the Northern Territory, South Austr ...
and
South Australia South Australia (commonly abbreviated as SA) is a States and territories of Australia, state in the southern central part of Australia. With a total land area of , it is the fourth-largest of Australia's states and territories by area, which in ...
, as well as
Western Australia Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Aust ...
. From these areas, the locusts can expand from time to time to be found in the agricultural areas of South Australia, New South Wales, including the
Riverina The Riverina () is an agricultural list of regions in Australia, region of south-western New South Wales, Australia. The Riverina is distinguished from other Australian regions by the combination of flat plains, a climate with significant seaso ...
, and
Victoria Victoria most commonly refers to: * Queen Victoria (1819–1901), Queen of the United Kingdom and Empress of India * Victoria (state), a state of Australia * Victoria, British Columbia, Canada, a provincial capital * Victoria, Seychelles, the capi ...
. The locust can be found in a variety of grassland and open wooded habitats across the inland areas of the Australian mainland. Upper-level winds may occasionally carry locusts to coastal areas of the mainland and northern
Tasmania Tasmania (; palawa kani: ''Lutruwita'') is an island States and territories of Australia, state of Australia. It is located to the south of the Mainland Australia, Australian mainland, and is separated from it by the Bass Strait. The sta ...
and may establish populations in the eastern valleys of the
Great Dividing Range The Great Dividing Range, also known as the East Australian Cordillera or the Eastern Highlands, is a cordillera system in eastern Australia consisting of an expansive collection of mountain ranges, plateaus and rolling hills. It runs roughl ...
; these populations usually fail to establish themselves for more than a few generations. Climatic change is projected to influence spatial patterns of pest outbreaks, as
climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...
is a primary limiting factor for insect dispersal. The most commercially important locust species in Australia is the Australian plague locust, Chortoicetes terminifera. Invasions wreak havoc on agricultural crops and pastures on a massive scale.


Life-cycle

Adult locusts feeding on green shoots that follow rain within 24 to 48 hours in warmer months will mature and lay eggs within 5 to 7 days of a rain event. Using their
ovipositor The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typica ...
s to drill a hole, locusts lay their eggs in the soil in a pod. Pods contain around 30 to 50 eggs and locusts lay two or three pods, 5 to 10 days apart. Egglaying often happens ''en masse'', with as many as a million laid in a hectare of suitable soil. In good conditions (i.e. warm and moist), eggs take around two weeks to develop. After hatching, the
nymphs A nymph (; ; sometimes spelled nymphe) is a minor female nature deity in ancient Greek folklore. Distinct from other Greek goddesses, nymphs are generally regarded as personifications of nature; they are typically tied to a specific place, land ...
take around 20–25 days to complete development in mid-summer. The locust has five
instar An instar (, from the Latin '' īnstar'' 'form, likeness') is a developmental stage of arthropods, such as insects, which occurs between each moult (''ecdysis'') until sexual maturity is reached. Arthropods must shed the exoskeleton in order to ...
s, with the wings becoming more prominent with each moult. After the first and second instars, nymphs form aggregations known as bands; these tend to disperse by the fifth instar. Late-instar bands travel up to 500 m per day. Drier country has large bands congregating that are visible from the air, while in the agricultural regions, bands tend to be smaller. After its final moult—6 to 8 weeks after egglaying—the adult locust is called a fledgling. Fledglings have three development stages; a growth phase, where wings are strengthened and the
exoskeleton An exoskeleton () . is a skeleton that is on the exterior of an animal in the form of hardened integument, which both supports the body's shape and protects the internal organs, in contrast to an internal endoskeleton (e.g. human skeleton, that ...
hardened, a fat accumulation stage, and lastly,
oocyte An oocyte (, oöcyte, or ovocyte) is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in a female fetus in the ovary during female gametogenesis. The female ger ...
development. Gregarious populations of locusts form swarms, recurring in central Eastern Australia once every two or three years. The Australian plague locust is less gregarious than other locust species and swarms occur in a continuum from dense swarms through a range of densities down to scattered adults. Swarms may persist for days, dispersing and reforming while following the wind. Swarms may move up to 20 km in a day. Swarms can infest areas up to , although typical infestations are less than . Swarms can travel up to , tending to move with hot winds and generally towards the coast in most cases.


Plagues

When food and climatic conditions are favourable, huge swarms of locusts may develop. The first recorded swarm was in 1844, with further outbreaks from the 1870s onward. After 1900, the intensity and frequency of locust swarms increased, and since the 1920s, a pattern has developed of localised, high-density populations in some locations most years and less frequent major plagues over large areas persisting for one to two years. Infestations in Western Australia are less frequent. Widespread heavy inland rains, especially in summer, allow plague locusts to reach plague proportions with less regular rain maintaining these high-density populations. During these conditions, the lifecycle pattern may change to one in which the period from hatching to maturity is reduced to 2.5 months. Dry conditions reduce populations back to background levels. Due to its large range and frequent plagues, the Australian plague locust is the most damaging locust species in Australia. Damage is mainly confined to
pasture Pasture (from the Latin ''pastus'', past participle of ''pascere'', "to feed") is land used for grazing. Types of pasture Pasture lands in the narrow sense are enclosed tracts of farmland, grazed by domesticated livestock, such as horses, c ...
, although crop damage can occur. Advanced winter crops have generally hardened off by early summer, when plague locusts become active and therefore are not favoured, but dry conditions and less advanced crops can be highly susceptible to locust infestation as can young autumn crops.


Human control

Losses in a plague can amount to $3–4 million if protection barriers are ineffective. The Australian Plague Locust Commission is responsible for the monitoring and control of locust outbreaks using the control agent
fipronil Fipronil is a broad-spectrum insecticide that belongs to the phenylpyrazole insecticide class. Fipronil disrupts the insect central nervous system by blocking the ligand-gated ion channel of the GABAA receptor ( IRAC group 2B) and glutamate-g ...
and growth regulators such as
diflubenzuron Diflubenzuron is an insecticide of the benzoylurea class. It is used in forest management and on field crops to selectively control insect pests, particularly forest tent caterpillar moths, boll weevils, gypsy moths, and other types of moths. ...
in the juvenile nymphal stage. Two older-generation
organophosphates In organic chemistry, organophosphates (also known as phosphate esters, or OPEs) are a class of organophosphorus compounds with the general structure , a central phosphate molecule with alkyl or aromatic substituents. They can be considered ...
,
fenitrothion Fenitrothion (IUPAC name: ''O'',''O''-dimethyl ''O''-(3-methyl-4-nitrophenyl) phosphorothioate) is a phosphorothioate (organophosphate) insecticide that is inexpensive and widely used worldwide. Trade names include ''Sumithion'', a 94.2% solutio ...
and
chlorpyrifos Chlorpyrifos (CPS), also known as chlorpyrifos ethyl, is an organophosphate pesticide that has been used on crops, animals, in buildings, and in other settings, to kill several pests, including insects and worms. It acts on the nervous systems ...
, are also used occasionally for auxiliary, blanket spray runs, and the bioinsecticide 'Green Guard', made from a native fungal isolate of ''
Metarhizium acridum ''Metarhizium acridum'' is the new name given to a group of fungal isolates that are known to be virulent and specific to the Acrididea (grasshoppers). Previously, this species has had variety status in ''Metarhizium anisopliae'' (var. ''acrid ...
''. The latter is based on technology developed by
CSIRO The Commonwealth Scientific and Industrial Research Organisation (CSIRO) is an Australian Government agency that is responsible for scientific research and its commercial and industrial applications. CSIRO works with leading organisations arou ...
and the
LUBILOSA LUBILOSA was the name of a research program management, programme that aimed at developing biological pest control, a biological alternative to the insecticide, chemical control of locusts. This name is an acronym of the French language, French ti ...
programme, and now accounts for more than 12% of spray applications: for protected, organic farming, or environmentally susceptible areas such as water courses.


See also

*
Agriculture in Australia Although Australia is mostly arid, the nation is a major agricultural producer and exporter, with around 421,000 people employed in agriculture, forestry and fishing as of 2023. Agriculture's farm gate output was $100 billion a year for a 5.7% ...
* APLC * Spur-throated locust, ''Austracris guttalosa'' – another plague locust in Australia * Yellow-winged locust, '' Gastrimargus musicus'' – a similar grasshopper


References

* Wang, B., Deveson, E. D., Waters, C., Spessa, A., Lawton, D., Feng, P., & Liu, D. L. (2019). Future climate change likely to reduce the Australian plague locust (Chortoicetes terminifera) seasonal outbreaks. The Science of the Total Environment, 668(1), 947–957. https://doi.org/10.1016/j.scitotenv.2019.02.439


External links


Department of Agriculture Forestry and Fisheries information page on plague locusts

''Save the Locust''
- information on learning to live with locusts * {{Authority control Locusts Agricultural pest insects Orthoptera of Australia Agriculture in Australia Oedipodinae Articles containing video clips Insects described in 1870