Locust Bulletin March 2016

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​​​​​​​​​​​​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 forecast and maps of locust distributions. 

Table of Contents


General situation in February and outlook to May 2016

Australian Plague Locust
Spur–throated Locust
Migratory Locust

Australian plague locust
Chortoicetes terminifera

The locust population increased in parts of Southwest Queensland and the Far North region of South Australia, where breeding in early January produced localised nymphs that fledged during the second half of February. Medium and high density late instar nymphs, associated with fledgling adults up to swarm density were recorded in limited habitat areas. Low density nymphs were also recorded at numerous locations in Central West Queensland. Population densities remained generally low elsewhere in these regions and in surveyed areas of the Far West, Far Southwest, Central West and Northwest regions of New South Wales, the Northeast and Northwest regions of South Australia, and in South Central Queensland. Heavy rainfall in inland Queensland and New South Wales in late January and early February maintained favourable habitat conditions for locust survival, but subsequent high temperatures have dried out pasture vegetation in many areas.

Surveys in Central West and Northwest New South Wales in mid-February identified low density adults in most areas and only occasional late instar nymphs. Low density adults were recorded in the Far West and Far Southwest regions, with a small area of high density young adults and residual late instar nymphs near Moolbong in the Hillston–Ivanhoe area.

Surveys in Southwest and Central West Queensland identified low density adults and mid–late instar nymphs in parts of Longreach Regional Council area, and in Barcoo and Quilpie Shires, with localised high density fledglings at one location west of Windorah. Only occasional low density adults were recorded during limited surveys in Bulloo and Paroo Shires. Fledgling adults were also identified by Biosecurity Queensland near St George in Balonne Shire. The yellow-winged locust infestation persisted in the Charters Towers district and high populations of other grasshopper species were reported in the Richmond–Winton area.

In the Far North region of South Australia, breeding in early January produced nymphs in habitat areas near Clifton Hills and Cordillo Downs. Surveys in mid-February identified medium–high density late instar nymphs and young adults in these areas. Only occasional low density adults were recorded elsewhere in the Far North, Northwest and Northeast regions.

The locust population remained low in northern Victoria. There were no reports of locust activity and no surveys were conducted.

The outlook for autumn is for adult numbers to increase in the Far North region of South Australia and in Southwest and Central West Queensland. The majority of nymphs from breeding in early January will have fledged in early March and further significant increases in population level are unlikely. The localised swarm density adults were recorded where nymphs were fledging and, although similar densities were likely to have developed in some other habitats in Southwest Queensland, widespread swarm formation is unlikely. Although these adults will be capable of breeding during March, favourable habitats will become restricted in the absence of further rainfall in those regions. A significant further generation of nymphs is therefore unlikely at this stage of the season as any eggs laid in southern regions will enter diapause dormancy. Only low density breeding is likely to have occurred in other regions during summer and population densities are expected to remain generally low. There is a moderate probability of migratory redistribution in western Queensland and northern South Australia during March, and of some southward migrations to Far West New South Wales or Northeast South Australia. There is a low risk of widespread infestations affecting agricultural regions in several states during autumn.

4 March 2016

Spur-throated locust
Austracris guttulosa

Surveys during February identified a consistent low density adult and nymph population in the Longreach and Blackall areas of Central West Queensland. Adults were recorded at Isolated–Scattered densities and there were Present density early and mid-instar nymphs at numerous locations. Isolated density adults were identified in Barcoo Shire in Southwest Queensland, with Present density early instar nymphs in the Windorah area. The Longreach light trap recorded this species on most nights during February, with over 40 individuals on 3, 24 and 28 February. Nymphs at various developmental stages were recorded at high density in an area west of Longreach at the end of February. Very few adults and no nymphs were recorded in Quilpie, Bulloo and Paroo Shires, or in northern New South Wales and South Australia.

The appearance of early-mid instar nymphs in Central West Queensland and Barcoo Shire reflects the favourable habitat conditions produced by rainfall during January. The expansion of green vegetation areas in these regions in January and February allowed egg laying to continue during February and enhanced the survival of nymphs. Egg development to hatching in this species takes 3-4 weeks and nymph development 8-10 weeks. Females can lay multiple times during summer. However, any nymphs hatching in late February or March may become susceptible to dry conditions, resulting in mortality in some areas.

Nymphs of this species usually do not aggregate to form bands, but can reach densities >30 m2 in locally favourable habitats. Nymph numbers are likely to peak in Central West Queensland during March, but residual late instars will be present during April. Fledging of early hatched nymphs will have commenced in mid-February and will continue during autumn. Significant nymph populations are also likely to have developed in parts of the Central Highlands, Northwest and Gulf regions of Queensland, and in the Northern Territory. Any egg laying in northern New South Wales or South Australia is likely to have produced only occasional low density nymphs.

The outlook is for an overall increase in the young adult population during autumn to a higher level than in recent years. There is a moderate risk of localised swarm formation during late autumn 2016, particularly in the Central Highlands and Central West regions of Queensland. Migrations of young adults can occur during autumn and swarms often form in forest areas and riparian tree lines during winter.

Migratory locust
Locusta migratoria

This species was not detected during surveys in February. However, the regions where it is more commonly found; the Central Highlands, eastern Central West and South Central regions of Queensland, were not surveyed. The low density population identified previously in these regions is likely to have persisted in some locations. The widespread heavy rainfall in these regions in January and early February will have maintained favourable habitats for continued low density breeding, but may limit the development of gregarious populations. This species is capable of continuous breeding during summer and autumn, resulting in populations comprising multiple life stages.

There is a moderate probability of small gregarious populations developing in parts of the Central Highlands or eastern Central West regions of Queensland during autumn. Gregarisation can occur at local scales and is often associated with cropping. However, the absence of any identified high densities or any nymphs at this stage of the season indicates a low probability of infestations developing during autumn 2016.

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 February to 29 February 2016

Local Distribution Map

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Situation in February and forecast to May 2016

New South Wales

Central West and Northwest Plains

Central West, Northwest and Central Tablelands Local Land Services

Locusts and conditions

  • The locust population remained at generally low densities in surveyed areas of these regions. The Central West Local Land Services (LLS) received reports of low numbers of locusts from near Gilgandra and Peak Hill.
  • Surveys of Central West LLS area in early February identified Isolated–Scattered density adults in the Coonamble, Carinda, Condobolin and Narromine districts, with low density mid-instar nymphs recorded at only one location. Very few locusts were recorded in the Nyngan–Bobadah area. In the Northwest LLS area, only occasional adults and late instar nymphs were identified in the Moree, Walgett and Lightning Ridge districts.
  • There was patchy light–moderate rainfall (<20-40 mm) in Northwest and Central Tablelands LLS areas, along with isolated falls around Coonamble during the first week of February. The heavy rainfall in some areas in late January maintained green vegetation in some areas, but high temperatures have dried pastures during February.

Forecast

  • Populations are likely to remain at generally low densities in most areas during autumn. Given the previous low population level in the region, any undetected breeding in late January is only likely to result in a moderate increase in adult numbers during March.
  • There is unlikely to have been any significant egg laying during February and there is unlikely to be a further cohort of nymphs in autumn. The majority of any eggs 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 widespread infestations developing autumn.

Riverina

Riverina and Murray Local Land Services

Locusts and conditions

  • Population level is likely to have remained low in most of the region during February. There were no reports of locust activity.
  • There was light–moderate rainfall (<20­–40 mm) in Murray LLS area during the first week of February.

Forecast

  • Given the low numbers of adults recorded in the region during January and the current dry habitat conditions, no significant breeding is likely to have occurred during February. However, habitat conditions were suitable for locust breeding in parts of the eastern Riverina during January and February, and moderate adult population densities could occur in some areas during March.
  • The majority of any eggs laid during March or April will enter diapause and not commence hatching until late September.
  • There is a low probability of any significant immigration from other regions during autumn.

Risks

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

Far West and Far Southwest

Western Local Land Services

Locusts and conditions

  • Population densities remained generally low in areas surveyed during February, but localised high density adults were identified in the Ivanhoe district.
  • Surveys in mid-February identified occasional Isolated density adults in the Broken Hill and Tibooburra districts. Following a report from Hillston LLS staff, Concentration density young adults and Present density fifth instar nymphs were identified at one location near Moolbong in the Ivanhoe district. Scattered–Numerous density adults had been recorded in this area in previous months and the young adults represent local breeding in early January. Isolated and Scattered density adults were recorded at other locations in that area.
  • No locusts were recorded at the White Cliffs light trap during February. Scattered density adults were reported in the Fowlers Gap area in late February.
  • There was patchy light rainfall (<20 mm) in the Wanaaring district in the first week of February. Vegetation remained green in localised areas in mid-February, but will have become mostly dry during the second half of the month.

Forecast

  • The absence of any significant rainfall during February will have limited opportunities for further locust breeding, except in limited areas of the Tibooburra district that received heavy rainfall in late January. Given the generally low known regional population density, any undetected breeding is likely to result in maintaining the low overall regional population density.
  • The majority of any eggs laid from late March in the Far West region, and from mid-March in the Far Southwest, will enter diapause and not hatch until early spring.
  • There is a moderate probability of some low density immigration from Southwest Queensland or the Far North of South Australia during March.

Risks

  • There is a low risk of a widespread regional infestation 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.

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Queensland

Southwest

Barcoo, Bulloo, Quilpie and Diamantina Shire

Locusts and conditions

  • Locust population density increased in Barcoo and Quilpie Shires as a result of breeding in early January.
  • Parts of Barcoo and Quilpie Shires were surveyed in mid-February. Isolated–Scattered density adults and Present density fourth and fifth instar nymphs were identified at numerous locations in the Windorah–Mt Howitt–Eromanga–Quilpie area. Late instar nymphs and swarm density young adults were identified in one area west of Windorah, but no other high density adults were recorded.
  • A report from near Lake Yamma Yamma indicates possible locally high density locusts also occurred elsewhere in favourable habitats in this region.
  • The Nooyeah Downs light trap recorded low numbers of locusts during 10-16 February.
  • Limited survey in the southern part of Bulloo Shire, and the Birdsville area in Diamantina Shire in mid-February identified Isolated–Scattered density adults, but no nymphs were detected.
  • There was moderate–heavy rainfall (20->40 mm) in Bulloo, Quilpie, Barcoo and part of northern Diamantina Shires during the first week of February, but no further significant rain was recorded. Vegetation remains green in habitat areas that received heavy rainfall in late January and early February.

Forecast

  • Many habitat areas remained favourable for further egg laying throughout January, but detected nymphs indicate egg laying occurred in the first half of the month. Rain in early February will allow young adults to mature eggs and further sporadic egg laying possibly occurred during the month. Further localised hatchings were therefore possible in late February and some nymphs may develop in March.
  • Adult population densities will continue to increase in March after the fledging of nymphs. A number of small swarms could form at fledging sites or as adults move to remaining favourable habitats, but the overall regional population is likely to increase to Numerous density during March.
  • There is a moderate probability of migratory redistribution within the region and some movements to adjacent regions during March.

Risks

  • There is a moderate risk of significant adult population increase, but a low risk of a widespread regional infestation developing in 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 generally low in surveyed areas during February, but nymphs identified in several areas indicate adult numbers will increase during March.
  • Limited surveys in mid-February identified Isolated density adults in the Longreach and Blackall-Tambo Regional Council (RC) areas. Present density third–fifth instar nymphs were detected at several locations.
  • The Longreach light trap recorded low numbers of locusts during 6–9 February.
  • There was moderate–heavy storm rainfall (20->40 mm) in the Central West region and in parts of Winton, Cloncurry and Boulia Shires during the first week of February. Pasture response has been patchy with green vegetation in localised areas.

Forecast

  • Adult numbers will increase to an overall Numerous density population in the Central West during March. Some localised higher densities and possibly small swarms could develop in Longreach or Blackall-Tambo RC areas. The detected nymphs indicate more widespread breeding was possible during January and February in the Central West, and similar favourable habitats also occurred in parts of Winton Shire. The early February rains extended favourable habitat conditions for nymph survival and possibly initiated further localised egg laying. This could produce some further localised nymphs in early March that would not fledge until the end of the month. A moderate increase in overall population density is therefore expected during March, but widespread swarm formation remains unlikely.
  • There is a moderate probability of some migratory redistribution within these regions during March, or of low density exchange migrations with Southwest Queensland.

Risks

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

Central Highlands

Central Highlands and Isaac Regional Council

Locusts and conditions

  • Locust densities are expected to have remained low during February.
  • No surveys were conducted and there were no reports of locust activity.
  • There was widespread heavy rainfall (>40 mm) throughout the region during the first week of February.

Forecast

  • Habitat conditions remained favourable for local breeding and provided further opportunities for egg laying during February. However, given the low previously identified population level, any egg laying is only likely to maintain the overall low regional population density in autumn.
  • There is a low probability of any significant 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

  • Locust density remained generally low in surveyed areas during February, but some localised breeding occurred in recent months.
  • Limited survey was conducted in part of Paroo Shire in mid-February. Only occasional Isolated density adults were identified in the Cunnamulla area.
  • Biosecurity Queensland officers investigated a locust report near St George in mid-February and identified a small area of fledgling adults and high density late instar nymphs west of town, but no other locusts were detected in the district.
  • There was widespread moderate rainfall (20-40 mm) rainfall in most areas of the region and some heavy falls (>40mm) in Maranoa Regional Council (RC) area during the first week of February. Pasture vegetation remains green in many areas, but is drying out in the western shires.

Forecast

  • Rainfall during February has maintained habitat conditions suitable for locust breeding in Maranoa and Western Downs RC areas, and in northern Murweh Shire. Despite several months of suitable soil and vegetation conditions, no known significant population increase has occurred. However, the nymphs near St George may indicate more widespread breeding occurred during January and a moderate increase in adult densities is therefore likely during March.
  • At this stage in the season, there is a low probability that further breeding will produce swarms in autumn.
  • There is a low probability of significant immigration from other regions during autumn.

Risks

  • There is a low risk of a widespread regional infestation 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.

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South Australia

Far North, Northeast, Northwest & Western Agricultural Region

Locusts and conditions

  • Locust densities increased in some habitat areas of the Far North region during February. Nymphs that resulted from early January breeding fledged from the middle of the month.
  • Surveys were conducted in the Northwest, Far North and Northeast regions in mid-February. Numerous–Subband density late instar nymphs, along with Numerous–Concentration density fledgling adults, were identified at a number of locations in the Clifton Hills and Cadelga areas in the Far North region. Most were associated with drainage line vegetation on stony plains. Band density nymphs and swarm density young adults were recorded at one location. The age distribution indicates egg laying in early January, after heavy rainfall in the region. Elsewhere in these regions only occasional adults were recorded, with a few Scattered density adults in the Arkaringa and Mt Dare areas in the Northwest.
  • Localised high density young adults were reported from Moolawatana, east of the North Flinders Ranges, in mid-February.
  • The Oodnadatta light trap recorded low numbers of locusts during 3–14 February.
  • There was light–moderate rainfall (20-40 mm) in the Western Agricultural region and patchy light rainfall (<20 mm) in the Marree district of the Far North region during the first week of February.

Forecast

  • Survey results indicate high density egg laying in early January was restricted to habitat areas in the northeast corner of the state. No nymphs were detected in similar green habitats in the Oodnadatta–Mt Dare or Marree–Mungeranie areas. However, the report from Moolawatana indicates that localised high density young adults may be more widespread during March.
  • Nymphs in the Far North will have fledged by the end of February and adult numbers will increase in early March. The formation of a few small swarms is possible, but vegetation is becoming dry in most locust habitat areas, so further significant breeding is unlikely in those areas and adults are likely to disperse or migrate.
  • There is a moderate probability of migratory redistributions or some small migrations to adjacent regions in South Australia during March. However there is a low probability of further successful breeding as a result of any migrations.

Risks

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

Murray Valley, Mt Lofty Ranges & Southeast Region

Locusts and conditions

  • The locust population is expected to have remained at a low level during February.
  • There was light–moderate rainfall (<20-40 mm) in parts of the Murray Valley and Southeast regions during the first week of February.

Forecast

  • There is a low probability of a significant population increase during autumn.
  • There is a low probability of any significant immigration during autumn.

Risks

  • There is a low risk of an 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.

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Victoria

North West & North Central Victoria

Locusts and conditions

  • Locusts are expected to have remained at low densities in Victoria during January.
  • No surveys were conducted and there were no locust reports.
  • There was localised light–moderate rainfall (<20–40mm) in parts of Northwest and North Central Victoria in the first week of February. Pastures remain dry in most areas.

Forecast

  • The locust population is expected to remain at low densities during autumn. At this stage in the season there is insufficient time for local breeding to produce a significant population increase during autumn.
  • There is a low probability of immigration into Victoria 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
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)
Victoria

Biosecurity 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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