Locust Bulletin November 2015

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

Table of Contents



General situation in October and outlook to January 2016

Australian Plague Locust
Spur–throated Locust
Migratory Locust

Australian plague locust
Chortoicetes terminifera

The locust population did not increase markedly in October, despite protracted hatching of nymphs from overwintering eggs in Central West New South Wales and adjacent regions. Nymphs consequently increased in these regions with a range of age cohorts apparent, and developed into localised medium to high density adults. Adult populations generally decreased to sparse but consistent low densities in the arid/semi-arid eastern interior, while medium densities persisted in Central West Queensland.

The southeast section of the eastern Australian locust habitat received moderate to heavy rainfall in the past month. In early October, there was little or no rain over the habitat, and only showers and light storms fell over scattered areas of the southeast in mid-October. Later in October, a surface trough over eastern Australia combined with a cold front crossing Tasmania produced moderate falls scattered across central NSW. A surface trough and low pressure system later developed in eastern Queensland and generated localised moderate storms from central Queensland to central NSW. At the end of October, another surface trough and cold front combination resulted in moderate to localised heavy storms over an area from central NSW extending to the Queensland gulf. The arid interior had light to localised moderate rainfall in early November. The current strong El Niño in the Pacific Ocean is forecast to persist until the end of the year, so warmer and drier conditions are generally expected in southeast Australia.

In Central West NSW and surrounding areas, hatchings were first reported in mid-September and continued to the end of October. The majority of bands were reported from the Dubbo-Gulargambone-Mullaley-Mudgee area, and some from Gunnedah-Narrabri-Moree-Tamworth-Quirindi and Condobolin-Nyngan-Forbes areas. The NSW Local Land Services conducted aerial surveys in mid- and late October and identified a number of bands scattered over a wide area of Central West and adjacent regions. Medium to high density adults were detected in Nyngan-Nymagee-Girilambone and Moree-Narrabri areas from surveys in late October, and such localised high density adults are expected to occur in other parts of this region despite landholder control. Only low-density adults were observed in the Far West and Riverina, and are likely to be present in the Far Southwest. Scattered low to medium density late instar nymphs were found in the Broken Hill area, while first hatchings were seen in the Deniliquin area in late October with more expected elsewhere in the Riverina.

Only localised medium density adults remained in the Tambo area of Central West Queensland, with low density adults found elsewhere. No further nymphs were detected during surveys in early November.

Adult numbers are forecast to have remained low in South Australia. Surveys were only conducted in the northeast corner of the Far North where occasional low density adults detected, but generally low density adults are expected in all regions. This is based on the very limited rainfall in October and only two isolated reports of late instar nymphs from Murray Valley and Southeast in the second half of October.

Low density adults are expected to have remained in northern Victoria, with localised hatchings expected in the coming weeks. Based on adult populations present at the end of autumn, the density and extent of these hatchings is forecast to be limited.

The outlook to January is for localised areas of high density adults in Central West NSW and surrounding areas, with a small chance of population redistribution. Low densities are expected to persist in the other regions of eastern Australia except for the Tambo region, with no significant immediate population build up resulting from recent rainfall. There is a low risk of widespread infestations across regions.

6 November 2015

Spur-throated locust
Austracris guttulosa

Following a report of high density adults from the Tarcombe area 120 km southwest of Longreach, surveys confirmed Concentration to Low-density-swarm densities present in the area. There were also consistent low-density adults found elsewhere in Central and Western Queensland, and occasionally in New South Wales and South Australia during surveys in mid-October and early November. The annual breeding sequence should be initiated soon after the recent widespread moderate to heavy rainfall in most central and eastern areas of Queensland and central and northeast of New South Wales. Localised hatchings are likely to appear from late November.

There is a low risk of widespread infestations, but a moderate probability of localised medium to high density nymph populations developing in Queensland during 2015.

Migratory locust
Locusta migratoria

There were very few migratory locusts detected in the areas surveyed from mid-October to early November, but the low-density adults found from previous surveys are expected to have remained in the Clermont and Springsure areas of the Central Highlands and South Central Queensland regions. The recent widespread moderate to heavy rainfall should encourage reproduction in these areas.

Landholders are encouraged to report any locust activities. There is a moderate probability of small gregarious populations developing in the Central Highlands region.

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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News

Detailed rainfall information is available on the Bureau of Meteorology website.

Maps of previous locust distributions can be found in the Locust Bulletins and are available on the APLC webpage.

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Australian plague locust distribution 13 October to 05 November 2015

Local Distribution Map

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Spur-throated locust distribution 13 October to 05 November 2015

Local Distribution Map

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Situation in September and forecast to December 2015

New South Wales

Central West and Northwest Plains

Central West, Northwest and Central Tablelands Local Land Services

Locusts and conditions

  • Locust sightings were reported throughout October from landholders in Central West, Northwest and Central Tabelands. Reports of hopper bands, continued hatchings and fledglings were followed up by NSW Local Land Services (LLS) staff. Over 130 confirmed cases were recorded mainly within the Dubbo-Gulargambone-Mullaley-Mudgee area, with some in the Gunnedah-Narrabri-Moree-Tamworth-Quirindi and Forbes-Condobolin-Nyngan areas. New hatchings continued to be reported at the end of October.
  • NSW LLS conducted aerial surveys in mid- and late October and identified more than 20 large-scale bands mainly in Central West. Landholders were provided with pesticides to implement localised ground control.
  • Surveys in late October identified Low-density-swarm adults in Nyngan-Nymagee-Girilambone area, and consistent Isolated to Scattered density adults in Coonamble, Narrabri and Moree districts with some localised Numerous to Concentration density adults. Present to Numerous density nymphs were also occasionally encountered, and nymph age varied widely.
  • Most of the region had dried out with only some localised green pasture vegetation remaining, but received moderate (20-40 mm) to heavy (>40 mm) rainfall from late October to early November, in addition to light falls in mid-October. Reports included Mendooran >105 mm, Coolah >90 mm, Dunedoo and Narrabri >80 mm, Dubbo and Mullaley 70-80 mm, Gilgandra and Moree >60 mm in the past three weeks.

Forecast

  • A moderate adult infestation is likely to continue in the area bounded by Dubbo-Gulargambone-Mullaley-Mudgee. Any overwintering eggs in this area would have hatched into nymphs already, and hopper bands and residual nymphal populations are likely to form some localised swarms in November.
  • Localised swarm formation is also likely in other parts of Central West and Northwest Plains.
  • Recent rainfall will generate favourable soil and pasture conditions for nymph development and adult reproduction. Sporadic egg laying is likely from mid-November.
  • The locust population is forecast to remain at moderate levels, with some likelihood of mature adults redistributing into adjacent regions. Nocturnal emigration may occur when disturbed weather occurs in this region.

Risks

  • There is a moderate risk of high density adults and localised swarm formation in the eastern Central West and adjacent regions.

Riverina

Riverina and Murray Local Land Services

Locusts and conditions

  • Surveys in mid-October detected only Isolated densities of adults remaining in the Narrandera-Jerilderie area, but no nymphs found.
  • Numerous density first and second instar nymphs appeared in the Deniliquin area in late October.
  • Pasture was drying off with some localised green vegetation. There was only light rainfall in this region in the beginning of mid-October in this region (Griffith 9 mm and Deniliquin 10 mm), but moderate (20-40 mm) totals recorded in one week time from the end of October in most areas with some heavy (>40 mm) falls. Hay received >100 mm, Hillston >70 mm, Deniliquin >60 mm, Narrandera >40 mm, Ivanhoe and Griffith >20 mm in the past week.

Forecast

  • Given the localised areas where high density adults were recorded in autumn, some nymph Bands may be expected to develop in the Deniliquin–Moulamein area. However, egg laying was likely to have been more widespread during autumn and low–medium density nymphs could hatch in other areas, particularly in the eastern Riverina.
  • Hatching could have occurred already from mid-October in northern areas and nymphs would have reached mid-instars by now. The bulk of hatching in the Deniliquin area would occur in early November and reach mid-instars later in the month. Fledging of the overwintering generation would start by the end of November.
  • Pasture vegetation will be green and sufficient for nymph development.

Risks

  • There is a moderate risk of localised, medium–high density nymphs developing in the southern and eastern Riverina.
  • There is a low probability of immigration into this region from adjacent regions during November.

Far West and Far Southwest

Western Local Land Services

Locusts and conditions

  • Adult populations decreased to sparse Isolated density in most areas except for the Bourke district where more consistent Isolated and Scattered density adults were detected along with some Numerous density adults from surveys in late October.
  • Occasional mid- to late-instar nymphs were found in the Broken Hill-Wilcannia-Tibooburra area.
  • Adults started to appear in light traps but at very low numbers.
  • The pasture vegetation was dry with only some green plant bases. There was very limited rainfall across entire area in October, except for some light rainfall patches in Brewarrina (>10 mm) and Wanaaring (>15 mm) areas in mid-October. Localised moderate (20-40 mm) to heavy (>40 mm) totals were recorded in Brewarrina (>90 mm), Bourke >60 mm (105 mm recorded in a farm of west of Bourke in 24 hours), Louth (~50 mm), and Wilcannia (~15 mm) areas in early November.

Forecast

  • Vegetation conditions should remain suitable for nymph development in some areas during November.
  • Low density adults will remain in most areas, and have limited opportunity to breed.
  • There is a low probability of immigration into this region during November.

Risks

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

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 & Diamantina Shire

Locusts and conditions

  • Surveys in Bulloo Shire in mid-October identified occasional Isolated density adults. Surveys in late October found a single Scattered density in Barcoo Shire, and only occasional Isolated density adults in Diamantina and Quilpie shires. No nymphs were detected.
  • Pasture vegetation was very dry. There was only very light rainfall (<10 mm) in the Bulloo Shire during October. Localised light to moderate (10-20 mm) rainfall has been recorded in early November, including Birdsville 14 mm, Eromanga 15 mm, and Bedourie 23 mm.

Forecast

  • Population levels will remain low during November.
  • Localised green vegetation will appear, but will not be sufficient for locust breeding without further significant rainfall in the near future.
  • There is a low probability of any immigration during November.

Risks

  • There is a low risk of a widespread infestation developing during November - December.

Central West & Northwest

Longreach, Barcaldine and Blackall - Tambo Regional Shire. Boulia, Cloncurry, Flinders, Mckinlay, Mt Isa, Richmond and Winton Shire

Locusts and conditions

  • Surveys of the southern half of these two districts in late October and early November identified Isolated density adults in most areas, but Scattered up to Numerous density adults were detected more frequently in the Tambo area. Generally more locusts were encountered towards the south.
  • Very few late instar nymphs were detected during these surveys.
  • Pasture vegetation was very dry. Light rainfall occurred in the second half of October, but moderate (20-40 mm) to heavy (>40 mm) rainfall were recorded in early November. Extreme heavy rainfall occurred in Barcaldine-Alpha area, 157 and 111 mm recorded respectively from 31 October to 2 November, and daily rainfall exceeding 100 mm in both areas on 1 November.

Forecast

  • The previous dry conditions limited development of the spring generation. However, recent heavy rainfall in most areas will provide favourable soil and vegetation conditions for breeding.
  • The improving habitat condition will encourage locust reproduction, but only moderate densities are expected to arise given the current low background population.
  • There is a low probability of any immigration during November.

Risks

  • There is a low risk of a widespread infestation developing during November and December.

Central Highlands

Central Highlands and Isaac Regional Council

Locusts and conditions

  • No further surveys were done in this district since late September to early October when only Isolated adults were detected.
  • There was light to moderate (10–20 mm) rainfall in the second half of October, and further patchy heavy storms in the beginning of November. Clermont received >80 mm, while Emerald and Springsure recorded 20-40 mm over a week time from late October.

Forecast

  • Vegetation was drying off in October, but recent localised moderate rainfall will generate suitable habitat conditions for locust breeding.
  • There is a low probability of any significant infestation developing in this region.
  • There is a low probability of any immigration during November and December.

Risks

  • There is a low risk of a widespread infestation developing in November-December.

South Central & Darling Downs

Balonne, Murweh and Paroo Shire. Maranoa, Western Downs and Goondiwindi Regional Council

Locusts and conditions

  • Surveys of South Central Queensland in late October identified consistent Isolated to Scattered density adults, but very few late instar nymphs remained.
  • Vegetation was dry but some green stems and localised green grasses were present. There was widespread light (<20 mm) to moderate (20–40 mm) rainfall from the second half of October to early November. Cunnamulla received 28 mm and Charleville recorded only 4.6 mm, but Mitchell recorded >70 mm and Roma and Dalby had 30-40 mm. Chinchilla received >90 mm in the same period.

Forecast

  • Adults will have the opportunity of breeding in some areas where pasture vegetation will respond to the recent moderate rainfall.
  • There is a low probability of immigration during November.

Risks

  • There is a low risk of a widespread regional infestation during November-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 Plagu​e Locust Commission.

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South Australia

Far North, Northeast, Northwest & Western Agricultural Region

Locusts and conditions

  • Surveys covered the Cordillo Downs area in the northeast corner of the Far North in late October, and identified occasional Isolated density adults.
  • Light traps recorded a few locusts in the second half of October.
  • Only one report of 4th instar nymphs was received near Orroroo in mid-October.
  • Vegetation was very dry. There was very little rainfall throughout October, but light–moderate (20–40 mm) falls in early November, including Woomera 6.6 mm, Tarcoola 20-35 mm, Marree 25.4 mm, and Arkaroola 29.4 mm.

Forecast

  • Any spring nymphs in these regions would have moulted into adults during October, but would not contribute to an obvious increase in overall adult population. Very dry vegetation conditions would have limited breeding opportunities in the absence of rainfall in November.
  • The distribution of moderate rainfall in early November will influence the likelihood and possible locations of any high density egg laying and nymph development during November or December.
  • There is a low probability of immigration during November.

Risks

  • There is a low risk of widespread regional infestation in November-December.

Murray Valley, Mt Lofty Ranges & Southeast Region

Locusts and conditions

  • No survey was done in this region in the past month.
  • There was only one report of 5th instar nymphs from the Spalding area in late October.
  • There was only light rainfall in the second half of October, but moderate–heavy rainfall (>40 mm) in early November, including Clare >50 mm, Murray Bridge >25 mm, and Lameroo 40-60 mm. Renmark recorded  <5 mm to add to the 11.8 mm on 21 October.

Forecast

  • Given the current low population level, there is only a low probability of a large population buildup in November and December.
  • There is a low probability of immigration during November and December.

Risks

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

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Victoria

North West & North Central Victoria

Locusts and conditions

  • No surveys were undertaken in Victoria in October, and no report of locust presence was received.
  • There was only light rainfall during October, and most areas received less than 10 mm. Widespread light–moderate rainfall (20–40mm) occurred during the first week of November with localised heavy fall in the Murrayville area (82 mm in 24 hours), Kaniva 33.4 mm, Nhill 18.6 mm, Horsham 16.4 mm, Boort 19 mm, Bendigo 31.4 mm and Echuca 18.2 mm.

Forecast

  • Hatchings would have commenced in northern Victoria from late October, but the bulk of any nymphs will appear in mid-November. There is a moderate probability of Present to Numerous density nymphs developing and persisting in localised areas of Northwest Victoria, with green vegetation from recent rainfall supporting any hatching population.
  • There is a low probability of immigration into Victoria during November.

Risks

  • There is a low risk of a widespread infestation developing during November and 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

Term

Definition

adultA winged locust
bandDense aggregation of nymphs, usually moving forward together
diapausePeriod of developmental suspension in response to predictable and 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
nymphImmature wingless locust. Often referred to as the hopper stage
swarmDense aggregation of flying adults, milling at the same spot or moving en masse

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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