Locust Bulletin March 2018

​ISSN 2204-9851

The Locust Bulletin is produced each month during the spring—autumn period and includes a general summary for each major locust species, details of known distributions with regional forecasts and maps of locust distributions.

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General situation in February and outlook for autumn 2018

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Australian plague locust - Chortoicetes terminifera

The locust population level remained low in most regions during February. Low numbers of adults were recorded in the Central West, Northwest Plains, Far West and Far Southwest of New South Wales, and in the Central West, Southwest and South Central regions of Queensland. Small increases in population density from very low levels in previous months were detected in part of Central West NSW and in Southwest Queensland. Although some localised low density breeding is likely to have occurred in other regions during January and February, most habitats dried out rapidly and prolonged high temperatures are likely to have caused increased mortality of nymphs and adults.

In New South Wales, surveys of the Far West, Far Southwest, Northwest Plains and Central West regions identified occasional low density adults in most areas. A localised area of high density young adults and residual late instar nymphs was identified in the Lake Cargelligo–Condobolin area of the southern Central West, indicating some breeding occurred there after heavy rainfall in December.

In Queensland, surveys of the Central West and parts of the Southwest and South Central regions identified low density adults, although recorded more frequently at transects than on previous surveys. No nymphs were detected.

No surveys were conducted in South Australia and no reports were received. Habitat conditions are dry in most regions and, based on previous surveys, locust population numbers are likely to have remained very low.

No surveys were conducted in Victoria and the only report was of yellow-winged locusts, Gastrimargus musicus. Locust population numbers are expected to have remained low.

The outlook for autumn is for population densities to remain generally low in most regions of inland eastern Australia. Rainfall during February was dominated by heavy storm events in eastern and northern Queensland. This will maintain favourable habitat for locust breeding in the Central Highlands, Central West and South Central regions, although aggregation and high density autumn egg laying is unlikely. Sporadic breeding will continue during autumn, and an autumn nymph generation is possible in several regions of Queensland. The majority of eggs laid in NSW, Victoria and equivalent latitudes in South Australia during March will enter diapause and not hatch until spring. Given the current low population levels, there is a low risk of regional infestations developing and a very low risk of swarms affecting any agricultural region during autumn. At this stage there is no indication of high density nymph infestations developing in any region during spring.

5 March 2018

Spur-throated locust - Austracris guttulosa

There is a widespread low density population of adults in inland Queensland. Surveys in February recorded Isolated–Scattered density adults in Central West Queensland and Isolated density adults in the surveyed parts of the Southwest and South Central regions. No nymphs were detected in surveyed areas. Previous surveys recorded low density nymphs south of Emerald in the Central Highlands and in the Roma–Mitchell area of the South Central region. Several heavy rainfall events in parts of the Central Highlands and South Central Queensland maintained favourable habitat for continued egg laying and nymph survival. However, previously recorded adult densities were low. Rainfall distributions suggest nymphs are likely to have developed in the Queensland Gulf region. Dry conditions during February are likely to have increased nymph mortality parts of Northwest, Southwest and Central West Queensland.

Fledging of nymphs will continue during March and April, with the possibility of a late cohort in the Queensland Central Highlands and South Central regions that would fledge in May. Young adults will gradually replace the current breeding population, but large population increases are unlikely except in the Queensland Gulf and Central Highlands regions. The likelihood of an overall population increase during 2018 compared to 2017 has declined.

Migratory locust - Locusta migratoria

This species was not detected by February surveys. Survey during January identified low numbers of adults in parts of the Queensland Central Highlands and South Central regions. Isolated density adults were recorded at several locations in the Central Highlands and Maranoa Regional Council areas, and in Banana Shire. This species is common in these regions and rapid population increases are possible in favourable habitat.  Gregarious populations can develop at local scales and are often associated with forage or cereal cropping.

The sequence of rainfall in the Central Highlands and South Central regions of Queensland during February has maintained favourable soil and vegetation conditions for continued breeding. An increase in overall population level in possible during autumn. Small gregarious populations could develop in localised areas during 2018. However, there is a low risk of a widespread infestation developing during autumn.

It is important that any locust activity be reported as soon as possible to your local biosecurity authority, primary industries department or to the commission. A toll–free call to the APLC can be made on 1800 635 962. An answering machine is attached for after–hours calls. Reports can also be e–mailed to APLC or made through the internet at Australian Plague Locust Commission.

Locust distribution map – Chortoicetes terminifera

Map of Australian plague locust distribution 1 February to 28 February 2018 

 

Australian plague locust (Chortoicetes terminifera)

Situation in February and forecast to May 2018

New South Wales

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Central West and Northwest Plains
Central West, Northwest and Central Tablelands Local Land Services

Locusts and conditions

  • A localised medium density population developed in the Condobolin–Lake Cargelligo area during February. Elsewhere in the Central West and Northwest Plains Local Land Services (LLS) areas, locusts were recorded at low densities.
  • Following a report in early February, Numerous–Concentration density young adults and residual mid–late instar nymphs were identified at several locations in the Condobolin–Lake Cargelligo district. The age distribution indicates breeding after heavy rainfall in early December. Habitat conditions were becoming dry in mid-February.
  • Survey of the Northwest LLS in mid-February identified only Isolated density adults in the Walgett, Narrabri, Moree and Brewarrina districts. Occasional Isolated density adults were recorded in Central West LLS, along with Present density mid-instar nymphs near Coonamble.
  • There was light–moderate rainfall (<20-40 mm) in Central Tablelands and eastern parts of Central West and Northwest LLS areas during the last week of February, with heavy falls (>40 mm) in parts of the Central Tablelands Pasture vegetation is becoming dry in most areas.

Forecast

  • Habitat conditions continued to dry out in most areas during February, which resulted in limited breeding opportunities. Locust densities are likely to remain low in these regions during autumn. Localised storm rainfall in parts of the Central West and the widespread rain in Northwest LLS area at the end of the January could have initiated some low density egg laying. Most resulting nymphs will develop at low densities.
  • The majority of eggs laid from early March in the Central West and mid-March in the Northwest LLS will enter diapause and not hatch until early spring.
  • There is a low probability of a large population increase during autumn.
  • There is a low probability of significant immigration from other regions during autumn.

Risks

  • There is a low risk of a widespread infestation developing during autumn.

Riverina
Riverina and Murray Local Land Services

Locusts and conditions

  • The regional locust population level is expected to have remained low during February. There were no reports.
  • Previous surveys identified only Isolated density adults in the region.
  • There was light–moderate rainfall (<20–40 mm) in the eastern districts of Riverina and Murray LLS areas during the last week of February. Pasture vegetation is becoming dry in most other areas.

Forecast

  • The locust population level is likely to remain low during autumn. Rainfall in eastern districts at the end of January could have initiated sporadic, low density egg laying and February rainfall may have maintained locally favourable habitat for nymph survival.
  • A small increase in autumn adult numbers is possible as a result of low density local breeding and migration from the Central West or Far Southwest regions. The majority of any eggs laid after early March will enter diapause and not complete development until spring. Autumn breeding is unlikely to result in significant nymph populations in spring.
  • There is a low probability of significant immigration from other regions during autumn.

Risks

  • There is a low risk of a widespread regional infestation developing during autumn.

Far West and Far Southwest
Western Local Land Services

Locusts and conditions

  • Locust population levels remained low in surveyed areas during February.
  • The Far Southwest and Far West regions were surveyed in mid-February. In the Far Southwest, only occasional Isolated density adults were identified in the Broken Hill, Menindee and Ivanhoe districts.
  • The Fowlers Gap and White Cliffs light traps recorded no locusts during February.
  • There was localised light rainfall (<20 mm) in these regions during the last week of February. There was localised light–moderate (20-40 mm) storm rainfall in the Bourke district during the last week of February. Pasture vegetation is now dry in most areas.

Forecast

  • Habitat conditions continued to dry out during February, which limited breeding opportunities and may have increased the mortality of any nymphs. Localised storm rainfall could have initiated sporadic egg laying, but only low density nymphs are likely to develop.
  • There is a low probability of a significant population increase during autumn. The majority of any eggs laid from mid-March will enter diapause and not hatch until spring.
  • There is a low probability of any significant immigration from other regions during autumn.

Risks

  • There is a low risk of widespread regional infestations developing during autumn.

All locust activity should be reported to your Local Land Services or the Department of Primary Industries, NSW. A toll-free call to the APLC can be made on 1800 635 962. An answering machine is attached for after-hours calls. Reports can also be e–mailed to APLC or sent through the web page at Australian Plague Locust Commission.

Queensland

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Southwest
Barcoo, Bulloo, Quilpie and Diamantina Shire

Locusts and conditions

  • The locust population level remained low in surveyed areas during February.
  • Survey of Quilpie and Barcoo Shires in mid-February identified Isolated density adults in most areas, with Scattered density adults in the Eromanga area. Although at low densities, locusts were recorded on most transects in habitat areas, which represents an increase in population level. Immigration from South Central Queensland and redistribution in mid-February could have contributed to this increase.
  • Sequences of high temperature (>40° C) days during January and February are likely to have resulted in increased mortality rates of adults and any nymphs.
  • The Birdsville and Nooyeah Downs light traps did not record any locusts during February.
  • There was localised light rainfall (<20 mm) in part of Quilpie Shire during the first week of February. Pasture vegetation is dry in most areas.

Forecast

  • Habitat conditions remain unfavourable for locust breeding. Given the very low population densities previously recorded, any eggs laid during autumn are likely to produce mostly low density nymphs. Without moderate–heavy rainfall, dry vegetation will increase nymph mortality rates. The majority of eggs laid after late March will enter diapause to hatch in early spring.
  • There is a low probability of a significant population increase in autumn.
  • There is a low probability of immigration from other regions during autumn.

Risks

  • There is a low risk of a widespread infestation developing during autumn.

Central West & Northwest
Longreach, Barcaldine and Blackall-Tambo Regional Council. Boulia, Cloncurry, Flinders, Mckinlay, Mt Isa, Richmond and Winton Shire

Locusts and conditions

  • The locust population level remained low in areas surveyed during February.
  • Survey in mid-February identified Isolated–Scattered density adults in the Longreach and Blackall-Tambo Regional Council (RC) areas No nymphs were detected.
  • The Longreach light trap recorded no locusts during February.
  • There was light–moderate localised storm rainfall (<20-40 mm) in the Central West and Northwest regions during the first week and last weeks of February, with localised heavy falls (>40 mm). Pasture vegetation remains dry in most areas.

Forecast

  • Locust population levels are expected to remain generally low in these regions during autumn. Rainfall during February provided localised egg laying opportunities and further low density egg laying is possible in March.
  • A localised, low density autumn nymph generation is likely to develop during March. Given the low adult population level, high densities or Bands are unlikely. The majority of eggs laid in March will develop to hatching, while any laid in April will enter diapause and hatch in early spring.
  • There is a low probability of any immigration from other regions during autumn.

Risks

  • There is a low risk of widespread regional infestations developing during autumn.

Central Highlands
Central Highlands and Isaac Regional Council

Locusts and conditions

  • Locust population densities are likely to have remained generally low during February. There were no reports.
  • Survey in late January identified Isolated–Scattered density adults in many habitat areas of Central Highlands RC and Banana Shire, with occasional adults in parts of Isaac RC area. Present density third–fifth instar nymphs were recorded in the Rolleston, Taroom and Mitchell districts, indicating some breeding occurred during December.
  • Several other species were also recorded, including low numbers of migratory and spur-throated locusts, and Numerous density Oedaleus australis, the eastern Oedaleus.
  • Nymphs of the yellow-winged locust, Gastrimargus musicus, were reported from near Collinsville in late February.
  • There was moderate–heavy storm rainfall (20->40 mm) throughout the region during 1–7, 15–21 and 22–28 February. Pasture grasses are green in many areas.

Forecast

  • Favourable habitat conditions for breeding were maintained throughout February in many areas. Localised low density egg laying could have commenced in mid-February and green vegetation will enable complete nymph development in March.
  • An autumn nymph generation is likely in the southern Central Highlands RC area or in Banana Shire. Nymphs will develop at mostly low densities, but localised higher densities are possible. A moderate increase in adult numbers to Scattered–Numerous density is likely in April.
  • There is a low probability of immigration from other regions during autumn.

Risks

  • There is a low risk of a widespread infestation developing during autumn.

South Central & Darling Downs
Balonne, Murweh and Paroo Shire. Maranoa, Western Downs and Goondiwindi Regional Council

Locusts and conditions

  • The locust population level remained generally low in surveyed areas during February.
  • Survey of the Augathella-Charleville area in mid-February identified Isolated–Scattered density adults.
  • There was moderate–heavy storm rainfall (20->40 mm) in eastern areas of the region during 1–7, 15–21 and 22–28 February. Pasture grasses are green in many areas.

Forecast

  • Locust population levels are likely to remain generally low during autumn. Favourable habitat conditions for breeding were maintained throughout February in many areas and will continue during March. Localised low density egg laying was possible in many areas and low density nymphs could develop at various stages in March. An autumn nymph generation is possible in Maranoa or Western Downs RC areas. Nymphs will develop at mostly low densities and a moderate increase in adult numbers to Scattered–Numerous density is possible in April.
  • Any eggs laid during February will develop directly and hatch during March, while the majority of those laid after mid-March will enter diapause and not hatch until early spring.
  • There is a low probability of significant immigration from other regions during autumn.

Risks

  • There is a low risk of a widespread regional infestation developing during autumn.

Locust activity should be reported to Biosecurity Queensland (Queensland Department of Agriculture and Fisheries) on 132 523. A toll free call to the APLC can be made on 1800 635 962. An answering machine is attached for after-hours calls. Reports can also be e–mailed to APLC or sent through the web page at Australian Plague Locust Commission.

South Australia

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Far North, Northeast, Northwest & Western Agricultural Region

Locusts and conditions

  • Locust population levels are likely to have remained very low in these regions during February as habitat conditions remained very dry in most regions.
  • No survey was conducted and there were no reports of locust activity.
  • The Dulkaninna and Oodnadatta light traps recorded no locusts during February.
  • There was light–moderate rainfall (<20–40 mm) in parts of the Western Agricultural and Northwest regions during the first week of February. Pasture grasses are dry in most other regions.

Forecast

  • Locust numbers are likely to remain low in these regions during autumn. The very low population level identified over recent months and continued dry habitats indicate that only sporadic low density autumn breeding is likely and that a significant spring nymph population is unlikely.
  • The only areas that have received rainfall over recent months are parts of the Western Agricultural and Northwest regions. Scattered–Numerous density autumn breeding populations could develop in localised areas.
  • The majority of any eggs laid during March in southern South Australia will enter diapause and hatch during spring, while in the north of the state those laid after mid-March will enter diapause and hatch in early spring.
  • There is a low probability of significant migrations into these regions during autumn.

Risks

  • There is a low risk of widespread regional infestations developing in autumn.

Murray Valley, Mt Lofty Ranges & Southeast Region

Locusts and conditions

  • Locust numbers are likely to have remained very low in these regions during February.
  • There was no significant rainfall (<20–40 mm) in these regions during February.

Forecast

  • Given the very low numbers identified in previous months and the generally dry habitat conditions, locust population level is likely to remain low during autumn.
  • There is low probability of any significant immigration during autumn.

Risks

  • There is a low risk of a widespread infestation developing during autumn.

Locust activity should be reported to Biosecurity SA (Primary Industries and Region South Australia) on the Locust Reporting Hotline on 1300 666 101. A toll-free call to the APLC can be made on 1800 635 962. An answering machine is attached for after-hours calls. Reports can also be e–mailed to APLC or sent through the web page at Australian Plague Locust Commission.

Victoria

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North West & North Central Victoria

Locusts and conditions

  • Locust numbers are likely to have remained very low during February.
  • No surveys were undertaken. Victorian Biosecurity and Agriculture received a report of yellow-winged locusts, Gastrimargus musicus, from the Mansfield area in late February.
  • There was light–moderate rainfall (<20–40 mm) in the eastern part of North Central Victoria during the last week of February. Vegetation in locust habitats is becoming dry in other areas.

Forecast

  • Given the low adult population level in previous months, any autumn breeding is likely to be at low densities. The majority of eggs laid during March and April will enter diapause and will resume development to hatch in spring.
  • There is a low probability of a significant nymph population developing during spring.
  • There is a low probability of any significant immigration during autumn.

Risks

  • There is a low risk of a widespread infestation developing during autumn.

Locust activity should be reported to Department of Economic Development, Jobs, Transport and Resources on 1300 135559. A toll-free call to the APLC can be made on 1800 635 962. An answering machine is attached for after-hours calls. Reports can also be e–mailed to APLC or sent through the web page at Australian Plague Locust Commission.

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Glossary of locust terms and density categories used in the Locust Bulletin

Locust biology and behaviour

TermDefinition
adultA fully winged, mature locust capable of breeding and migrating
bandDense aggregation of nymphs, usually moving forward together
diapauseDormancy in autumn laid eggs avoiding winter environmental conditions
egg bedAn area of soil containing many egg pods (up to 1000 per square metre)
fledgeFinal nymphal moult to a soft-bodied adult incapable of long-distance flight
instarDiscrete stages of nymphal development each separated by a moult
layingFemale locusts each depositing clutches of 20-60 eggs into the ground in froth-lined egg pods
nymphJuvenile wingless locust, often referred to as the hopper stage
swarmDense aggregation of adults, milling at the same spot or flying closely together

Locust density categories

Where higher densities occur, a large proportion of the regional population is concentrated in very small areas with lower densities elsewhere, so the higher densities cannot be extrapolated over the area of an entire region. A range of density classes is usually found within a surveyed region.

Nymph DensitiesNumber per m2
Present1 – 5
Numerous6 – 30
Sub–band31 – 80
Band> 80
Adult DensitiesNumber per m2Number per hectare
Isolated– 0.02< 200
Scattered0.03 – 0.1> 200 – 1000
Numerous0.2 – 0.5> 1000 – 5000
Concentration0.6 – 3.0> 5000 – 30,000
Low Density Swarm4.0 – 10> 30,000 – 100,000
Medium Density Swarm11 – 50> 100,000 – 500,000
High Density Swarm> 50> 500,000
General density classesNymph densitiesAdult densities
very low, occasionalNil–PresentNil–Isolated
lowPresentIsolated–Scattered
mediumNumerous—Sub–bandScattered–Numerous
highBandsConcentration–Swarms

Reporting locust infestations

It is important that all locust activity is reported as soon as possible to your nearest state agriculture agency office or to the Australian Plague Locust Commission.

StateAuthority for reporting locusts
New South WalesLocal Land Services (LLS) or Department of Primary Industries
QueenslandBiosecurity Queensland, Department of Agriculture and Fisheries
South AustraliaBiosecurity SA, Primary Industries & Regions South Australia (PIRSA)
VictoriaBiosecurity Agriculture, Department of Economic Development, Jobs, Transport and Resources

Reports to the Australian Plague Locust Commission can be made by:

Free call (Canberra): 1800 635 962 (24 hours)
Fax (Canberra): (02) 6272 5074
E–mail: APLC
Internet: Australian Plague Locust Commission

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