Locust Bulletin October 2017

​​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 September and outlook to December2017

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Australian plague locust - Chortoicetes terminifera

Locust populations declined to low densities in most regions of New South Wales, Victoria, Queensland and South Australia during autumn. Medium density adults persisted in parts of the Far North region of South Australia during March, but habitat conditions became dry. Regions in the eastern half of NSW and Queensland received moderate-heavy rainfall during March, which could have initiated some localised autumn egg laying, particularly in the NSW Central West and Northwest Plains, or in Central West, South Central and the Central Highlands of Queensland. However, there was little winter rainfall and September remained dry in all regions, so habitat conditions are unsuitable for nymph survival in most areas. Surveys during September identified only low density adults and occasional nymphs.

In New South Wales, survey of the northern Central West and Northwest Plains identified only occasional low density adults. No nymphs were detected.

Survey was conducted in the Central Highlands and parts of the Central West and South Central regions of Queensland in early September. Low density adults and occasional late instar nymphs were identified.

In South Australia, surveys in late September identified only occasional adult locusts in the Far North region and around the Flinders Ranges.

There was no survey or report information from Victoria during September. Any spring hatching will commence in mid-October.
Current locust distributions are at low background population densities. Dry habitat conditions will limit the survival of spring generation nymphs. Low soil moisture may also have left some eggs in quiescence, which could hatch after moderate rainfall. The outlook for the remainder of spring is for population densities to remain low in all regions of inland eastern Australia. Spring hatchings have been reported in parts of the Western Australian wheatbelt, including Katanning and Wongan-Ballidu Shires. Landholders have carried out some control in localised areas.

The probability of population increases during November and summer is dependent on the distribution of moderate–heavy rainfall during the next three months. Given the current very low population densities, rapid development of widespread regional infestations is unlikely during summer. However, seasonal rainfall forecast models suggest an average rainfall expectation over coming months and even isolated heavy rainfall events can result in localised large population increases.

4 October 2017

Spur-throated locust - Austracris guttulosa

Adult population levels in autumn 2017 were lower than those of recent years in Queensland. There was a widespread medium density population of young adults and residual nymphs in the Northwest, Central West Central Highlands and South Central regions of Queensland during March, but no swarms were identified or reported. Young adults of this species live through winter in a non-reproductive state, often forming swarms that occupy woodlands and riparian tree lines. Migrations and local swarm movements can occur during spring and early summer.

Survey in September identified only Isolated density adults in the Central Highlands and parts of the Central West and South Central regions of Queensland. Breeding does not usually commence until the onset of the northern wet season. Habitat conditions in most regions are currently unfavourable for breeding. Egg development to hatching in this species takes 3–4 weeks and nymph development a further 8–10 weeks. Females can lay multiple times during summer, usually following significant rainfall. Nymphs of this species do not usually aggregate to form cohesive bands, but can reach densities of 30/ m2 in favourable habitats.

There is currently a low risk of swarms developing or migrating into agricultural regions during the remainder of spring and summer. The outlook is for the maintenance of moderate population levels during 2017–18.

Migratory locust - Locusta migratoria

Survey of the Queensland Central Highlands and the northern South Central region during September identified low density adults at several locations south of Emerald. Isolated density adults were recorded in the Rolleston and Taroom–Roma areas but no nymphs were detected. Populations of this species are commonly found in these regions and rapid population increases are possible in favourable habitat.  Gregarization can occur at local scales and is often associated with forage or cereal cropping.

Small gregarious populations could develop in localised areas of the Central Highlands during 2017-18. However, there is a low probability of a widespread infestation developing in the Central Highlands, eastern Central West or South Central regions of Queensland during spring or summer.

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 September to 30 September 2017 

 

Australian plague locust (Chortoicetes terminifera)

Situation in September and forecast to December2017

New South Wales

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

Locusts and conditions

  • The locust population is at very low density in surveyed areas and there were no reports.
  • Surveys in Central West and Northwest Local Land Services (LLS) areas in late September identified only occasional Isolated density adults in most areas. Isolated–Scattered densities were recorded in the Collie and Quambone districts.
  • Hatching of autumn laid eggs will have commenced during September, where soil moisture allowed complete development.
  • Parts of these regions received 50–100 mm rainfall during March and moderate falls during May, but no significant rainfall during winter or September. Pasture grasses are now dry in most areas.

Forecast

  • Only low density nymphs are likely to develop during October, particularly in eastern parts of the Central West or Northwest LLS areas. Fledging of any nymphs in October and November is unlikely to contribute to a noticeable population increase. It is possible that some eggs remain in quiescence due to low soil moisture. Moderate rainfall in October or November could produce some late low density hatchings.
  • There is a low probability of significant immigration from other regions during October or November.

Risks

  • There is a low risk of widespread infestations developing during spring or December.

Riverina
Riverina and Murray Local Land Services

Locusts and conditions

  • Locust population level is expected to have remained very low during September. No APLC surveys were conducted and there have been no reports.
  • Given the very low locust numbers in autumn, only sporadic low density egg laying was possible.
  • The region received moderate rainfall (20–40 mm) during April and May. There was further moderate rainfall in Murray LLS area during July and August. Pasture vegetation is dry throughout most of the region.

Forecast

  • Spring hatching will have commenced in late September in northern districts through to mid-October in the south. The absence of green pasture vegetation could reduce nymph survival in most areas.
  • Nymphs are only likely to develop at low densities and are unlikely to contribute to any significant population increase during spring.
  • Dry habitat conditions will limit breeding and egg laying during October and November.
  • There is a low probability of significant immigration from other regions during spring or December.

Risks

  • There is a low risk of a widespread regional infestation developing during spring or December.

Far West and Far Southwest
Western Local Land Services

Locusts and conditions

  • Adult locust densities are expected to have been very low during September, given the dry habitat conditions.
  • Only sporadic low density egg laying was possible during autumn.
  • No APLC surveys were carried out and there were no reports.
  • The Fowlers Gap and White Cliffs light traps recorded no locusts in August or September.
  • Parts of the Far Southwest region received moderate rainfall (20–40 mm) during April and August. Pasture vegetation was very dry in most areas during September.

Forecast

  • Spring hatchings will have commenced in early September in the Far West to mid-September in the Far Southwest region. The dry habitat conditions are likely to reduce nymph survival in most areas.
  • Fledging of any nymphs will commence in early November in the Far West region and mid-November in the Far Southwest. This is unlikely to contribute to any significant population increase.
  • Dry habitat conditions will limit breeding and egg laying during October and November.
  • There is a low probability of any significant immigration from other regions during October or November.

Risks

  • There is a low risk of a widespread regional infestations developing during spring or December.

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

  • Medium density adults persisted in a few areas in March, but habitats became dry and numbers declined in late autumn.
  • There were no APLC surveys and no locust reports during September.
  • The Birdsville and Nooyeah Downs light traps did not record any locusts during August or September.
  • There was patchy light rainfall (<20 mm) in parts of the region during July. Pasture vegetation is very dry in most areas.

Forecast

  • Only sporadic low density egg laying was likely during autumn and winter. Low density hatchings may have occurred during August and September, but the absence of green vegetation could reduce nymph survival in many areas. Fledging of surviving nymphs in October is unlikely to contribute to any significant population increase.
  • Dry conditions will limit locust breeding or egg laying during October and November.
  • There is a low probability of immigration from other regions during spring or December.

Risks

  • There is a low risk of a widespread infestation developing during spring or December.

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 was low in areas surveyed during September. There were no reports.
  • Part of Barcaldine Regional Council (RC) area was surveyed in mid-September. Only occasional adults and Present density late instar nymphs were identified in the Alpha area.
  • The Longreach light trap recorded no locusts during August or September.
  • Most areas in these regions have received no significant rainfall since March. There was light rainfall in Blackall-Tambo and Longreach Regional Council (RC) areas and in Winton and Boulia Shire during July. Pasture vegetation is very dry.

Forecast

  • Locust population level is expected to remain low in these regions during spring.
  • The absence of green vegetation will reduce nymph survival and fledging nymphs are unlikely to contribute to a significant population increase during spring.
  • Dry habitat conditions will limit breeding and egg laying during October and November.
  • There is a low probability of any immigration from other regions during spring or December.

Risks

  • There is a low risk of a widespread regional infestations developing during spring or December.

Central Highlands
Central Highlands and Isaac Regional Council

Locusts and conditions

  • Locust population level was low in surveyed areas during September.
  • Survey of Isaac and Central Highlands RC areas in mid-September identified Isolated density adults in most areas, with Scattered density adults near Taroom. Present density late instar nymphs were detected at one location in the Clermont area.
  • There was an unconfirmed report of low numbers of locusts from the Comet area in early September.
  • Most of this region received no significant rainfall since March. Pasture vegetation was dry in September.

Forecast

  • Locust population level is likely to remain generally low for the remainder of spring. Fledging of remaining nymphs is unlikely to contribute to any significant increase in population densities.
  • Rainfall distribution during the remainder of spring and December will influence the likelihood of any significant population increase during summer.
  • There is a low probability of immigration from other regions during spring or December.

Risks

  • There is a low risk of a widespread infestation developing during spring or December.

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

Locusts and conditions

  • Locust population levels remained low in areas surveyed in September. There were no reports.
  • Limited survey was conducted in Maranoa Regional Council (RC) area and Murweh Shire in mid-September. Isolated density adults were identified in the Roma–Mitchell–Injune area, with Present density late instar nymphs at one location.
  • There was light rainfall in Murweh Shire, and in Maranoa and Western Downs RC areas in early July. Pasture vegetation is dry in most areas.

Forecast

  • Locust population level is likely to remain low for the remainder of spring. Fledging of remaining spring generation nymphs is unlikely to contribute to any significant increase in population densities.
  • Rainfall distribution during November and December will influence the likelihood of any significant population increase during summer.
  • There is a low probability of significant immigration from other regions during spring or December.

Risks

  • There is a low risk of a widespread regional infestation developing during spring or December.

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

  • Medium density adults persisted in parts of the Far North region during March and early April, but habitats became dry in most areas. Only a very low density background population was identified in September. There were no reports of locust activity.
  • Surveys in late September identified only occasional Isolated density adults around the North Flinders Ranges. No locusts were detected in the Far North region from Maree to Oodnadatta, in the Northwest from Coober Pedy to Woomera or on the western side of the Flinders Ranges. There were more consistent Isolated density counts in the Southern Flinders Ranges area from Hawker to Port Augusta.
  • The Dulkaninna light trap did not record any locusts in August or September.
  • The Northeast, Northwest and Western Agricultural regions received moderate rainfall (20–40 mm) totals during April, but there was no significant rainfall during winter. Ground vegetation in locust habitats was dry during September. There was moderate–heavy rainfall in the Oodnadatta area on 30 September.

Forecast

  • Locust population level is likely to remain low for the remainder of spring. Dry habitat conditions will limit the survival of any spring generation nymphs and any breeding or egg laying. It is possible that some eggs remain in quiescence due to low soil moisture. Moderate rainfall in October or November could produce some late low density hatchings.
  • Hatching of nymphs would have commenced in August in the Far North and September in the Northeast and Western Agricultural regions, where soil moisture allowed complete egg development. Fledging of surviving spring nymphs is unlikely to contribute to any significant population increase.
  • Rainfall distribution during the remainder of spring and December will influence the likelihood of breeding and any significant population increase during summer.
  • There is a low probability of significant migrations into these regions during spring or December.

Risks

  • There is a low risk of widespread regional infestations developing in spring or December.

Murray Valley, Mt Lofty Ranges & Southeast Region

Locusts and conditions

  • Locust densities are expected to have remained very low. No APLC surveys were conducted and there have been no reports.
  • The Southeast and Mt Lofty regions received moderate rainfall (20-40 mm) totals during July and August, and further moderate falls during the first week of September. Pasture vegetation remains green in localised areas.

Forecast

  • Locust population level is likely to remain very low for the remainder of spring. Low density nymphs could develop in a few locations during October and November.
  • There is low probability of any significant immigration during spring or December.

Risks

  • There is a low risk of a widespread infestation developing during spring or December.

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

  • The locust population declined to very low background level during autumn. Only sporadic low density egg laying was possible.
  • There has been no APLC survey and no locust reports.
  • Parts of North Central and Northwest Victoria received moderate–heavy (20->40 mm) monthly rainfall totals during July and August.

Forecast

  • Spring hatchings will commence in early October in the Northwest region and mid-October in North Central Victoria and the Wimmera district. Only occasional low density nymphs are likely to develop in Victoria. Fledging of nymphs in late November or December is unlikely to contribute to a significant population increase.
  • There is a low probability of any significant immigration during spring or December.

Risks

  • There is a low risk of a widespread infestation developing during spring or December.

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
diapausePeriod of dormancy in anticipation of unfavourable 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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