Locust Bulletin April 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 March and outlook for spring 2017

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Australian plague locust - Chortoicetes terminifera

Locust populations remained at low densities in most regions during March. However, medium density adult populations were maintained in the Far North region of South Australia and in parts of Southwest Queensland, as a result of breeding in late January. Several small swarms were recorded in the North Flinders Ranges area in late March. Few nymphs were recorded during March, indicating only limited egg laying during February. Habitat conditions in these regions are now mostly unsuitable for autumn breeding. There is unlikely to be significant numbers of nymphs in any region during April or May. Heavy rainfall was limited to the eastern regions of New South Wales and Queensland during March. Parts of Central West and Northwest New South Wales and the South Central, Darling Downs and Central Highlands regions of Queensland received heavy storm rainfall in late March. Habitat conditions will remain favourable for autumn breeding in those regions, but current population levels are low. Most eggs laid in autumn will enter diapause dormancy and not hatch until spring.

The locust population remained at low densities in New South Wales during March. Only occasional low density adults were identified in surveyed areas of the Central West and Riverina regions. More consistent Isolated–Scattered density adults were recorded in the Broken Hill–Tibooburra and White Cliffs–Wanaaring areas of the Far West region. No nymphs were detected during surveys and habitat conditions are now generally dry in most regions.

In Queensland, medium density adults were recorded in the Quilpie and Bulloo Shires of the Southwest region in early March. Medium density adults and occasional late instar nymphs were also identified in the Arcadia Valley and Emerald areas of the Central Highlands. Consistent low density adults were identified in the Longreach and Blackall-Tambo areas of the Central West, the Mitchell–Morven–Augathella area of the South Central region and the Taroom area in Banana Shire. Occasional late instar nymphs were detected in the Augathella–Morven area.

In South Australia, medium density adults and occasional late instar nymphs were identified in the Hawker area in early March, with low density adults elsewhere in the Northeast and the Murray Valley region. Surveys at the end of March identified a widespread medium density adult population in the Far North region, extending from Frome Downs to Murnpeowie in the North Flinders Ranges, across to Maree and Oodnadatta. Localised swarm activity was recorded in the Arkaroola area.

Population levels remain low in Victoria. Surveys in early March identified only occasional adults in the Northwest and North Central regions.

The outlook for the remainder of autumn is for locust population densities to remain generally low in most regions of New South Wales and Queensland. Adult numbers are likely to decline to low densities in the Far North, Northeast and Western Agricultural Northwest regions of South Australia during April and May. The probability of migrations within South Australia will decline by May, but some southward movements are possible in April. Medium density populations could breed in parts of the Northeast and Western Agricultural regions. The majority of eggs laid during April in all regions will be at low densities and will remain in diapause dormancy during winter. There is a low probability of swarm infestations in any state during autumn. Consequently, there is a low risk of widespread nymph infestations developing in agricultural regions during spring.

4 April 2017

Spur-throated locust - Austracris guttulosa

A widespread medium density population was recorded throughout inland Queensland during February and March, with a relative decline in breeding adult and nymph numbers detected in some regions. There were also widespread, low and medium density nymphs in Central West and Northwest Queensland, and similar populations are likely in to be the Queensland Gulf region. Low density nymphs were recorded in the Southwest and South Central regions.

Surveys in March identified Scattered–Numerous density adults in the Clermont area of the Central Highlands, the Blackall–Barcaldine–Tambo area of the Central West and the Charleville–Augathella area of South Central Queensland. Lower densities of adults were recorded in Banana Shire, areas south of Emerald in the Central Highlands Regional Council (RC area) and the Roma–Mitchell area in Maranoa RC area. Present density nymphs, mostly at late instar stages, were recorded at numerous locations in the Blackall–Tambo and Clermont areas, and occasionally in other parts of these regions.

Isolated–Scattered density adults were recorded in Quilpie and Bulloo Shires of Southwest Queensland and Isolated density adults in the Far West region of NSW and the Far North region of South Australia.

Heavy rainfall was restricted to parts of the Central West, South Central, Central Highlands and Gulf regions of Queensland during March. This will enable remaining nymphs in those areas to survive to fledging. Females can lay several pods over the course of the wet season, but hatchings will decline in April. Egg development to hatching in this species takes 3–4 weeks and nymph development a further 8–10 weeks. Fledging of nymphs hatched in previous months will continue and the numbers of young adults will increase during autumn. These will largely replace the previous generation as it ages and declines, although some swarms of immature adults are likely to form in late autumn. Those adults will not breed before next spring. There is a low risk of a large increase in overall population level during 2016–17.

Migratory locust - Locusta migratoria

Low numbers of adults were recorded south of Emerald in the Central Highlands and north of Roma in South Central Queensland in early March. Surveys identified mostly Isolated density adults in the Springsure–Injune, Buckland Plains and Arcadia Valley districts in the Central Highlands Regional Council (RC) area. Isolated–Scattered density adults were identified in the Taroom area of Banana Shire and in the Roma–Mitchell area of Maranoa RC. Numerous density adults were recorded at one location between Roma and Taroom. No nymphs were detected.

Rapid population increases can occur in the Central Highlands, eastern Central West and South Central regions of Queensland. Patchy storm rainfall during each week of March, and heavy rainfall at the end of the month will maintain favourable habitat conditions for continued breeding during autumn. Small gregarious populations could develop in localised areas of the Central Highlands, but there is a low probability of a widespread infestation developing during autumn or spring.

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.

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Australian plague locust distribution 1 March to 4 April 2017

Map of Australian plague locust distribution 1 January to 3 February 2017

Spur-throated locust distribution February-March 2017

Map of Spur-throated locust distribution February to March 2017

Australian plague locust (Chortoicetes terminifera)

Situation in March and forecast for spring 2017

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 remained at low densities during March. There were no reports of locust activity.
  • Surveys in the southern Central West Local Land Services (LLS) area in early March identified occasional Isolated density adults in the Narromine, Tottenham and Condobolin districts. No nymphs were detected.
  • There was light–moderate rainfall (<20-40 mm) in parts of the Central West and Northwest regions during each week of March, with localised heavy storms (>40 mm) in several areas. Total March rainfall in several districts was >100 mm. Pasture vegetation is becoming green in those areas.

Forecast

  • Autumn breeding is likely to be at low densities. The majority of eggs laid during April will enter diapause dormancy and not hatch until late August in the Northwest LLS area and September in the Central West LLS.
  • The adult population is likely to remain at low densities during the remainder of autumn, but heavy rainfall in parts of the Northwest and Central West at the end of March could initiate some Numerous density aggregation and sporadic egg laying during April.
  • Nymphs are likely to develop at low-medium densities during spring, but localised small Bands are possible in favourable habitats.
  • There is a low probability of significant immigration from other regions during April or May.

Risks

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

Riverina
Riverina and Murray Local Land Services

Locusts and conditions

  • The locust population remained at low densities during March and there were no reports.
  • Only occasional Isolated density adults were recorded in the Hay, Hillston, Narrandera, Deniliquin and Moulamein districts during surveys in in early March. No nymphs were detected.
  • There was patchy light rainfall (<20 mm) in the eastern areas of Riverina LLS during 15-21 March and widespread moderate rainfall (20-40 mm) across the region during the last week of the month. Pasture vegetation remains dry in most areas.

Forecast

  • No significant locust breeding is likely during autumn, given the dry habitat conditions in most areas and the low level background population.
  • The majority of any eggs laid during autumn will enter diapause and remain dormant during winter.
  • Spring hatchings will start in late September in the northern districts and October in the southern part of the region.
  • There is a moderate probability of low density migrations from adjacent regions.

Risks

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

Far West and Far Southwest
Western Local Land Services

Locusts and conditions

  • Locust population levels remained at low density in surveyed areas during March. Habitat conditions were unfavourable for breeding in most areas.
  • Surveys of the Far West region in early March identified Isolated–Scattered density adults in the Broken Hill–Milparinka–Tibooburra and White Cliffs–Wanaaring areas. No nymphs were detected.
  • Occasional Isolated density adults were identified in the Broken Hill–Wentworth area of the Far Southwest region.
  • The Fowlers Gap and White Cliffs light traps only recorded very low numbers of locusts during the second half of March.
  • There was light–moderate rainfall (<20–40 mm) in the Bourke and Brewarrina districts during 8–14 March, and in the Ivanhoe, Cobar and Bourke districts during 15–21 March. Pasture vegetation is mostly dry in locust habitat areas.

Forecast

  • There is unlikely to have been any significant breeding during March, as most habitats are dry.
  • Sporadic egg laying in April will produce mostly diapause eggs that will not hatch until spring. Hatching will commence in early September in the Far West region and mid-September in the Far Southwest.
  • Nymphs are likely only to develop at low–medium densities during spring.
  • There is a moderate probability of small migrations from the Far North region of South Australia during April, becoming less likely in May.

Risks

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

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 adult population remained at generally low densities in surveyed areas during March, but Numerous density adults persisted in parts of Quilpie and Bulloo Shires. The maintenance of medium density adult populations is likely to be the result of local breeding in late January.
  • Surveys in early March identified Scattered–Numerous density adults in the Quilpie and Kihee–Noccundra areas. Isolated–Scattered density adults were recorded in other areas. No nymphs were detected.
  • Surveys in Barcoo and Bulloo Shire at the end of March identified Isolated–Scattered density adults in the Stonehenge–Windorah and Morney–Arrabury areas.
  • No locusts were recorded at the Birdsville or Nooyeah Downs light traps during March.
  • There was light rainfall (<20 mm) in parts of Quilpie and Barcoo Shires during 8–15 March and localised light–moderate falls in Bulloo and Quilpie Shires during the last week of the month. Vegetation is now mostly dry in locust habitat areas.

Forecast

  • Habitat conditions are mostly unfavourable for locust breeding in much of the region. Adult numbers should decline to low levels in late autumn.
  • Only sporadic low density egg laying is likely in April or May. The majority of eggs laid in April will enter diapause and remain dormant during winter. Low density hatchings are likely from late August.
  • There is a moderate probability of some low density exchange migration with adjacent regions during April.

Risks

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

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 remained at generally low levels in surveyed areas during March.
  • Limited surveys of the Central West in early March identified consistent Isolated–Scattered density adults in the Blackall-Tambo Regional Council (RC) area and occasional adults in the Barcaldine RC area.
  • The Longreach light trap recorded no locusts during March.
  • There was moderate–heavy rainfall (20->40 mm) in the northern shires of these regions during each of the last three weeks of March. The Longreach, Barcaldine and Blackall-Tambo RC areas received moderate–heavy falls during 15–21 March.

Forecast

  • Locust population levels are expected to remain generally low in these regions during April and May. Any breeding is likely to produce only localised, low density nymphs in winter and spring.
  • There is a low probability of significant immigration during April or May.

Risks

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

Central Highlands
Central Highlands and Isaac Regional Council

Locusts and conditions

  • The locust population level remained generally low during March, but medium density adults were recorded in several areas.
  • Surveys in early March identified Scattered–Numerous density adults in the Clermont, Capella and Arcadia Valley districts, with Isolated–Scattered densities in the Springsure–Buckland and Taroom districts. Occasional late instar nymphs in the Arcadia area indicate continued breeding of the local population.
  • There was patchy, moderate–heavy rainfall (20->40 mm) in parts of the region each week during March. There was heavy storm rainfall associated with Cyclone Debbie at the end of March.

Forecast

  • Rainfall during March provided localised favourable vegetation and soil conditions for locust breeding. Egg laying could produce low density nymphs in some areas, while a proportion of eggs would enter diapause and not hatch until early spring. Nymphs would likely only develop at low–medium densities, but localised high densities are possible.
  • There is a low probability of immigration from other regions during April or May.

Risks

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

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

Locusts and conditions

  • Locust population levels remained generally low in surveyed areas during March. There were no reports of locust activity.
  • Surveys in part of Murweh Shire in early March identified Isolated–Scattered density adults and occasional late instar nymphs in the Mitchell–Morven–Augathella area. Only occasional adults were recorded in Maranoa and Western Downs RC areas.
  • There was patchy moderate–heavy storm rainfall in Balonne Shire and light–moderate rainfall (<20-40 mm) in Murweh Shire and Maranoa RC area during 8–14 March and widespread light–moderate falls (<20–40 mm) during 15–21 March. There was heavy rainfall (>40 mm) in Western Downs and Goondiwindi RC areas during the last two weeks of March.

Forecast

  • Heavy rainfall will produce favourable breeding habitats in eastern districts during April. Given the low known population levels, autumn breeding will be mostly be at low densities and is likely to produce only low–medium density nymphs in spring. However, some localised aggregation is possible in favourable habitats during April, which could result in small areas of higher density nymphs. Most eggs will enter diapause and start hatching in late August.
  • There is a low probability of significant immigration from other regions during April or May.

Risks

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

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 adult populations were maintained in favourable habitat areas of the Far North region during March, largely as a result of localised breeding in late January and continued migration activity.
  • Surveys of the Northeast region in early March identified Numerous density adults and occasional late instar nymphs in the Hawker–Cradock area. There were Isolated–Scattered density adults in the Orroroo–Peterborough–Burra area and only occasional adults in the Yunta area.
  • Surveys of the Far North region in late March identified consistent Numerous density adults from Frome Downs to Moolawatana on the eastern side of the North Flinders Ranges, along with localised small swarms near Arkaroola. Females from swarms were accumulating fat. Numerous density adults were identified from Murnpeowie to Maree and across to Oodnadatta. No nymphs were detected.
  • Surveys of the Far West region in late March identified Isolated–Scattered density adults north and west of Oodnadatta to the NT border, south to Marla and Coober Pedy. Only occasional adults were recorded south of Coober Pedy to Woomera and Port Augusta.
  • Late March surveys in the Northeast region identified Isolated–Scattered density adults in the Quorn–Hawker area, but only occasional adults in other areas.
  • The Dulkaninna light trap recorded no locusts during March. The Oodnadatta light trap was not operational.
  • There was no significant rainfall in these regions during March. Vegetation has become dry in most locust habitat areas.

Forecast

  • Vegetation and soil conditions became unfavourable for breeding in most habitat areas during March. Only sporadic egg laying is likely in the Far North region, except in localised drainage line habitats flanking the Flinders Ranges during April. Most eggs will enter diapause dormancy and hatch in early spring.
  • Spring hatchings will start in late August in the Far North region, and in September in the Northeast and Western Agricultural regions. Most nymphs are likely to be at low–medium densities and are more likely to develop in the in the Northeast and Western Agricultural regions.
  • Nymphs in the Western Agricultural region will have fledged during March and could persist in areas of green habitat during April. However, most eggs laid in April will enter diapause and remain dormant during winter.
  • Adult numbers will decline to low densities in most regions in May.
  • There is a moderate probability of small migrations from the Far North region to the Northeast or Murray Valley regions during April, but are less likely in May.

Risks

  • There is a moderate risk of small southward migrations from the Far North region to the Northeast or Murray Valley regions during April.
  • There is a low risk of widespread regional infestations during autumn or spring.

Murray Valley, Mt Lofty Ranges & Southeast Region

Locusts and conditions

  • Locust densities remained low in surveyed areas during March.
  • Surveys in early March recorded only occasional adults in the Morgan–Renmark area. No nymphs were detected.
  • There was very light rainfall (<10 mm) in these regions during 8–14 March and localised moderate (20–40 mm) falls in the Southeast during 15–21 March. Pasture vegetation is drying off in many areas.

Forecast

  • Only low density egg laying is likely during April or May. Most eggs will enter diapause and remain dormant during winter. Any hatching will occur in October, but no significant nymph population is likely to result.
  • Small migrations from the Northeast or Far North regions are possible during April. These are unlikely to significantly increase the autumn breeding population.

Risks

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

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 population levels remained generally low during March, and there were no reports of locust activity.
  • Survey of Northwest Victoria in early March detected no locusts between Mildura, Ouyen and Murrayville. Survey in the Echuca–Boort–Kerang area identified only occasional adult locusts.
  • There was light–moderate rainfall (<20-40 mm) in parts of North Central Victoria during 15–21 and 22–28 March. Pasture vegetation remains dry in most locust habitat areas.

Forecast

  • Any breeding of the local population during April will produce diapause eggs that will remain dormant during winter. Hatching would follow in October.
  • Given the very low known population densities, autumn breeding is likely to result in sporadic low density nymphs in spring.
  • There is a moderate probability of small migrations from northern South Australia into Northwest Victoria during April. The likelihood of immigration will decline during May.

Risks

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

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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