Locust Bulletin September 2010

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 and rainfall events. 

Locust Bulletin September 2010 - table of contents

General locust situation
Australian plague locust situation
Australian plague locust map August 2010
Forecast development times
Rainfall winter 2010
Terms and Abbreviations used in the Bulletin
Map of forecast districts used in the Bulletin
Map of forecast regions used in the Bulletin

General situation in August and outlook to October 2010

Australian Plague Locust
Spur-throated Locust
Migratory Locust

The spring outlook is for a serious widespread nymphal infestation of locusts in several regions of New South Wales, northern Victoria and eastern South Australia as a result of extensive egg laying by adult swarms during autumn. The plague situation, where numerous regions across several states are affected by high densities of locusts, could continue during summer if there is a high level of nymphal survival in spring.

The widespread heavy rainfall in inland areas during last summer and autumn produced favourable habitat conditions, allowing three generations of population increase during 2009-2010. A large number of swarms formed in New South Wales, northern South Australia and southwest Queensland in early April 2010. Migrations to the south during April brought swarms into the Murray Valley and Northeast regions of South Australia, Northwest and North Central Victoria and the southern Riverina in New South Wales. Despite intensive control of nymphs of the third generation in New South Wales, eggs laid in autumn will produce a further generation of high density nymphs during spring.

Inter-agency meetings have continued to plan and coordinate the response to the anticipated spring populations in New South Wales, Queensland, South Australia and Victoria. State agencies and industry groups are conducting landholder information meetings in areas likely to be affected. Information to assist landholders prepare for and implement locust control has been developed and made available through websites, industry group newsletters and discussions at landholder meetings.

Widespread high density hatching of eggs and the development of nymphal bands is expected during spring in the Central West, Far Southwest and Riverina regions of New South Wales, the Northwest and North Central regions of Victoria, and the Northeast and Murray Valley regions of South Australia. More localised high density hatchings are likely in Far West New South Wales, Southwest Queensland and the Far North and Southeast regions of South Australia. Formation of swarms could occur during November and December, following the fledging of nymphs.

In New South Wales spring hatching of eggs will commence in early September in northern areas, during September in the Central West and Far West, and from early October in the Riverina and Far Southwest. In South Australia hatchings will commence in mid-September in the Flinders Ranges area and the Murray Valley, and will continue during October in southern areas. Spring hatchings will commence in late September in Northwest Victoria, through to mid-October in areas south of Echuca and late October in the Horsham area.

Spring hatching at most locations will be distributed over a period of several weeks and timing will vary depending on local conditions and temperatures during early spring. Variations are likely as a result of the high proportion of non-diapause eggs laid during late autumn and differences in soil type. Lower than average temperatures during July and August in southern states and high soil moistures levels indicate later peak spring hatching times than in recent years. However, samples show embryo development in non-diapause eggs is more advanced in sandy soils than in loam or predominantly clay soils. This is likely to be significant in Northwest Victoria and the Murray Mallee district in South Australia, where protracted hatchings are likely to occur from mid-September to mid-October.

  

•  Spur-throated locust           Austracris guttulosa
  

Swarm formation continued in Central West, South Central and Southwest Queensland during July and August. The over-wintering adult population in these regions is significantly larger than has occurred in recent years. Surveys by Biosecurity Queensland in the Central West region identified many swarms in the Barcaldine–Blackall and Tambo–Charleville areas. Swarms were also identified in the Thargomindah–Cunnamulla and Bollon areas. Biosecurity Queensland officers carried out aerial control of 109 swarms during June–August, covering a total area of over 26,000 ha.

There were numerous reports of swarm activity in the Hughenden, Winton, Richmond and Julia Creek areas of Northwest Queensland and in the Thargomindah-Cunnamulla area of Bulloo and Paroo Shires during July and August. The swarms are formed by immature adults which are the offspring from breeding during the 2009-2010 wet season. Similar densities of adults are likely to be in the Queensland Gulf region, other shires of Southwest and Northwest Queensland and in Murweh, Balonne and Paroo Shires in South Central Queensland. Only Isolated–Scattered density adults were detected in the Central Highlands in Autumn, but swarms were reported from near Laglan, in the west of Isaac Regional Council area, at the start of September. APLC survey during August identified low density adults in Murweh and Roma–Mitchell–St George areas, but consistent Numerous density adults and several swarms in the Cunnamulla-Bollon area.

In New South Wales Numerous–Concentration density adults were identified in the Brewarrina–Goodooga area of Northwest Livestock Health and Pest Authority (LHPA) area during April, but survey in early August detected mostly Scattered–Numerous density adults in this area. Surveys in August and early September show a widespread Scattered–Numerous density adult population throughout Darling and northern Western LHPA areas.

An increase in adult numbers and formation of swarms in late autumn is usual for this species. Migratory activity of immature adults can result in regional population redistribution during autumn and again in late spring. Adults form largely sedentary swarms during winter, which may move into woodland areas. Breeding of adults usually commences in November and December in Queensland, but could occur earlier if heavy rainfall continues in western Queensland in September or October. The population densities in the Central Highlands remained low during winter, but migration at the start of the wet season could result in an increase in swarm numbers in this region and in the Northwest LHPA of New South Wales. The outlook is for a significant adult summer breeding population in parts of Southwest, Northwest and Central West Queensland. If there is high rainfall during spring and summer in several regions of western Queensland, widespread successful breeding could result in a further significant population increase in 2011.

 

• Migratory locust                Locusta migratoria

APLC surveys in during August identified occasional Isolated density adults of this species in the Cunnamulla and Roma areas in South Central Queensland and also in the Goodooga–Collarenebri area of the Northwest LHPA in New South Wales. Continued rainfall and green vegetation conditions in these regions has provided suitable conditions for breeding and continued low–medium density populations are likely during September and October. Heavy rainfall in the Queensland Central Highlands during August could also initiate egg laying and a potential population increase in that region.

   

6 September 2010

• Australian plague locust situation

  New South Wales
  Queensland
  Victoria
  South Australia

Probable Australian plague locust infestattions: spring 2010

Forecast hatching and development times

Forecast development dates for indicative locations during spring 2010

Location - NSW	Egg laying	Hatching	Mid-instar	Fledging
Brewarrina-Bourke	April	7 September	22 September	15 October
Tibooburra-Wanaaring	April	10 September	25 September	18 October
Broken Hill-Wilcannia	April	15 September	30 September	22 October
Ivanhoe-Hillston	April	25 September	13 October	2 November
Nyngan-Tottenham	April	15 September	6 October	26 October
Tullamore-Condobolin	April	5 October	19 October	7 November
Dubbo-Peak Hill	April	6 October	20 October	11 November
Parkes-Cowra	April	14 October	28 October	17 November
Forbes-West Wyalong	April	12 October	26 October	14 November
Hay-Balranald	April	5 October	21 October	4 November
Wagga-Cootamundra	April	25 October	6 November	26 November
Narrandera-Griffith	April	15 October	29 October	17 November
Jerilderie-Deniliquin	April	18 October	31 October	20 November
Location - Victoria	Egg laying	Hatching	Mid-instar	Fledging
Mildura-Ouyen	April	25 September	14 October	5 November
Swan Hill-Boort	April	6 October	25 October	14 November
Echuca-Bendigo	April	24 October	6 November	25 November
Shepparton-Tungamah	April	20 October	3 November	22 November
Nhill-Warracknabeal	April	17 October	1 November	20 November
Horsham-Stawell	April	24 October	6 November	1 December
Location - SA	Egg laying	Hatching	Mid-instar	Fledging
Marree-Lyndhurst	April	2 September	17 September	10 October
Andamooka-Roxby	April	5 September	21 September	15 October
Hawker-Orroroo	April	24 September	10 October	30 October
Port Augusta-Quorn	April	19 September	4 October	27 October
Renmark-Morgan	April	26 September	12 October	4 November
Pinnaroo-Karoonda	April	2 October	21 October	10 November
Keith-Bordertown	April	17 October	1 November	25 November
Kimba-Cowell	April	1 October	18 October	10 November
Location - QLD	Egg laying	Hatching	Mid-instar	Fledging
Thargomindah	April	24 August	9 September	3 October

Peak hatchings dates are a guide only, as hatchings will extend for several weeks before and after the dates given. Forecast dates are based on development models for known or possible egg laying by adult populations and assume sufficient soil moisture for development after diapause. Dates are estimated using recorded temperatures to 30 August and long-term average temperatures. Dates indicate the majority of the population entering the life stage. Egg laying occurred over an extended period during autumn. Egg development rate is sensitive to temperature variation in late winter and early spring and early hatchings have occurred in recent years.

NEW SOUTH WALES

Situation in August and forecast to mid-October 2010

Central West

Lachlan, Central West & Central North LHPA

Locusts and conditions

• Swarm density egg laying occurred in many locations in the Central West and Lachlan LHPA areas during April. Low density early hatchings were reported in the northern Central West at the start of September, but the bulk of the nymph population will emerge from mid-September in northern Central West LHPA, and early October in the southern areas. Peak hatching in western Lachlan LHPA is expected at the start of October and from mid-October in east. Many Bands are expected to develop throughout the region during October.

• Limited survey in late August did not identify any significant population of over-wintering nymphs.

• In Central West LHPA area large swarms appeared in the Nyngan area in the second half of April and egg laying was observed at a number of locations. First low density hatchings were reported from this area on 2 September, but the majority of nymphs are likely to emerge in mid-September. There was more sporadic swarm activity in the Narromine–Warren–Trangie and Coonamble–Quambone areas and localised high density hatchings are expected in mid-September. In the eastern parts of the Central West there were egg laying reports from the Dubbo–Wellington, Peak Hill and Yeoval-Cumnock areas, where hatchings are likely from early October.

• In Lachlan LHPA area, the majority of swarms resulted from breeding within the region, and swarms persisted in some areas from March to May. Extensive egg laying occurred in the Condobolin–Lake Cargelligo, Tullamore–Tottenham and West Wyalong–Ungarie areas during March and April, where high density hatchings are likely from late September. Swarm density egg laying continued in the eastern part of Lachlan LHPA during April and May. Hatchings and localised Band development are expected in the Cowra–Canowindra, Grenfell–Young, Parkes-Eugowra and Forbes–Quandialla areas from mid-October.

• Sporadic swarm egg laying was reported from the Merrygoen–Gilgandra, Mullaley, Tambar Springs and Dunedoo–Mudgee areas of Central North LHPA in April.

• There were frequent moderate falls of rain during winter, which have maintained green pasture and crop conditions. Total rainfall for July throughout the region exceeded 50 mm. Pastures are green throughout the region.        

Forecast

• Many Bands are likely to develop in Central West LHPA area from mid-September in the north, to mid-October in the south and east. The intensity of hatchings and Band development is likely to reflect the occurrence of swarm activity during autumn. Based on the distribution of swarms in April, the Nyngan–Trangie area is likely to have a high intensity of hatchings, but some Bands are also likely to develop in the Coonamble–Armatree, Warren–Gilgandra, Dubbo–Wellington, Peak Hill and Yeoval–Cumnock areas.

• Persistent swarm activity in autumn and egg laying reports indicate widespread hatchings and Band development throughout the Lachlan LHPA, commencing in late September in the west to mid-October in the east. Hatchings are likely in the Condobolin–Lake Cargelligo and Tullamore–Tottenham areas from late September, followed by Band formation in early October. Hatchings should occur progressively later further east, with the majority of nymphs emerging in mid-October in the West Wyalong, Forbes, Parkes and Cowra districts.

• Localised hatchings and some Bands may develop in western parts of the Central North LHPA from early October.

• The majority of eggs laid during March and early April would have entered diapause and ceased development during May. However, the proportion of non-diapause eggs laid increases during April and nearly all eggs laid during May do not enter diapause, but develop slowly when soil temperature exceeds 16^o C. Eggs are often laid near the soil surface during autumn and non-diapause eggs in sandy soils in exposed locations could have developed past the mid-embryo stage by late autumn. Therefore eggs in sandy soils are likely to commence hatching earlier than forecast dates in the table. Lower than average temperatures recorded during July and August, along with continued rainfall, has resulted in slow development of many eggs laid in heavier soils. These conditions are likely to produce more protracted hatchings over September and October than has occurred in recent years, resulting in nymphs over a range of development stages during October and November.

• Continued rainfall in most parts of the region during winter has maintained soil moisture levels, so that egg quiescence as a result of dry soils is unlikely to cause delayed hatchings during spring. Dense vegetation and moist conditions could result in cooler local soil temperatures and later hatchings in some locations.  

Risk(s)

• There is a high probability of a high density nymphal generation with widespread Band development in Central West and Lachlan LHPA areas during October.

• There is a risk of localised damage to cereal and other crops in this region during October.

• Some swarm formation is likely to occur during November, following the fledging of nymphs.   

Riverina

Riverina & Hume LHPA

Locusts and conditions

• Extensive high density egg laying occurred throughout this region by swarms during autumn. Swarm numbers increased throughout the Riverina during April, largely as a result of fledging of the local March nymph population. Southward migration of swarms resulted in the infestation extending throughout Riverina. A serious nymphal infestation with many Bands is expected to develop during October and November.

• In the Narrandera and Wagga districts swarm egg laying was recorded from early March through to mid-May.

• In the Hay–Hillston area swarm egg laying began in mid-April and continued into mid-May.

• Swarms moved into the Jerilderie–Deniliquin area in early April and egg laying was recorded in many locations extending south to the Murray River near Mathoura and Tocumwal. Many Bands are expected to develop in the Colleambally–Jerilderie, Berrigan–Finley and Deniliquin–Mathoura areas. More localised Bands are likely in the Lockhart–Urana–Rand area and areas south of Wagga.

• In the Balranald–Moulamein area swarms developed from Bands which developed locally during March. High density egg laying was reported during April.

• Swarms moved into the eastern part of Hume LHPA during March and egg laying was reported. from Junee, Bethungra, Stockinbingal, Wallendbeen and Temora. Egg laying was reported near Wagga and The Rock in late March, but there were few reports from southern part of Hume LHPA.

• Most of the Riverina received total rainfall >50 mm for the months of May and August. And moderate totals (20–40 mm) for June and July. Pasture vegetation is green in most areas.  

 Forecast

• A widespread major infestation of nymphs, forming many Bands is expected during spring. The cumulative result of continuous egg laying in the Narrandera and Wagga districts during March–May is likely to be many high density hatchings and Bands, particularly in areas north of Narrandera and Wagga. The bulk of hatchings are likely to occur in mid-October in the Narrandera–Griffith–Rankins Springs area. Eggs sampled during winter from sites laid during March–May in the Narrandera and Wagga disitricts showed that the majority of eggs laid after mid-April did not enter diapause. Samples from 12 egg beds indicated that the proportion of pods affected by the parasitic wasp Scelio fulgidis ranged from 15–70% and that Scelio was active even during May. Because of the high number of egg beds in the area, it is unlikely that parasitism will have a significant effect on the number of Bands forming in spring.

• In the Hay–Hillston area early hatchings are likely in sandy soils from mid-September, but the bulk of nymphs should emerge at the start of October. In the Jerilderie–Deniliquin area early hatchings are likely from the start of October in sandy exposed sites, but the bulk of the population is expected to emerge from mid-October. In the Balranald–Moulamein area the bulk of hatching is likely to occur from the start of October, but eggs laid in sandy sites could commence hatching from mid-September.

• The bulk of hatchings in the Hume LHPA are expected from mid-October.

• The majority of eggs laid during March and early April would have entered diapause and ceased development during May. However, the proportion of non-diapause eggs laid increases during April and nearly all eggs laid during May do not enter diapause. Eggs are often laid near the soil surface during autumn and non-diapause eggs in sandy soils in exposed locations could have developed past the mid-embryo stage by late autumn. Eggs in sandy soils are likely to commence hatching several weeks earlier than forecast dates in the table. The lower than average temperatures recorded during July and August, along with continued rainfall, has resulted in slow development of eggs laid in heavier clay soils. These conditions are likely to produce more protracted hatchings over September and October than has occurred in recent years, resulting in nymphs over a range of development stages during October and November.

• Fledging of nymphs will commence from early November in the northern and western districts, through to late November in the eastern and southern parts of the regions. Swarm formation is likely to follow in the weeks after fledging. A significant swarm population could develop in December.    

Risk(s)

• There is a high probability that a serious pest infestation of nymphs forming many Bands will develop during October and November.

• There is a high probability of some swarm formation during December by locusts remaining after fledging in November.

• There is a risk of localised damage to cereal and other crops in the region during October and November.   

Northwest Slopes and Plains

Northwest LHPA

Locusts and conditions

• Locust population remained at low–medium densities in most areas during late autumn, with only the southern corner of the Walgett district near Carinda recording some swarms. Surveys at end of August in the Collarenebri–Mungindi area identified only occasional adults.

• Most of the region received total rainfall >50 mm for July and moderate (20–40 mm) totals for August.  

Forecast

• Based on the autumn distribution of adults, this region is unlikely to experience a significant infestation during spring. However, some localised hatchings and medium density nymphs are possible in southern Walgett and Narrabri districts from early September.

• This region had the lowest infestation level of all reporting regions in NSW during autumn. Surveys suggested there was no significant immigration during autumn. The probability of immigration from adjacent regions will increase in November after fledging of the spring generation of nymphs.    

Risk(s) 

• There is a low probability of a significant nymph infestation in this region during spring. Some localised high density nymphs could develop in the western areas of the Walgett district.   

Far West

Darling & Western LHPA

Locusts and conditions

• A large number of swarms formed in this region in early April and subsequent migrations resulted in a general southward redistribution of the adult population. Egg laying by swarms was reported in a few locations near Broken Hill, but was likely to have been more widespread in the Broken Hill, Wilcannia and White Cliffs districts. Some localised high density egg laying may also have occurred in the southern parts of the Bourke and Brewarrina districts.

• Survey in the Bourke–Enngonia–Goodooga area in early August identified only occasional Isolated density adults.

• Survey in the White Cliffs, Wanaaring and Tibooburra areas at the end of August detected only occasional Isolated density adults. No nymphs were found during survey and hatching had not commenced at the known egg bed site at Langawirra. There was a range of other species, including Austracris guttulosa, at Scattered–Numerous density throughout surveyed areas.

• There was moderate rainfall (20–40 mm) in the southern parts of the region during May, June and August. Rainfall during July gave monthly totals >50 mm throughout the region.    

Forecast

• There were few confirmed reports of egg laying in April, but it is likely that there are many egg beds in areas north of Broken Hill–Wilcannia, despite the emigration of swarms from this region. Aerial survey is planned during September to assess the extent of any high density nymphs in the region.

• Cooler than average temperatures and frequent rainfall are expected to delay hatchings until early September in the Tibooburra area and mid-September in the Broken Hill–Wilcannia area. The frequency and amount of rainfall during winter indicates that hatching will not be delayed by quiescence due to dry soil conditions.

• Many nymphal Bands are likely to develop in the Broken Hill, White Cliffs, Wilcannia, Tibooburra, Wanaaring and Tibooburra areas during September. Fledging will occur after mid-October.  

Risk(s)

• There is a moderate probability that a significant infestation of nymphs with many Bands developing in parts of Western and Darling LHPA areas during September.   

Far South West

Western LHPA

Locusts and conditions

• Swarms formed after the widespread infestation of nymphal Bands fledged at the end of March. Swarms extended through much of the region during April, including the Hillston–Ivanhoe–Booligal and Pooncarie–Wentworth–Willandra Lakes. Swarm egg laying was reported in the Balranald–Clare area, but egg beds are likely to be widespread throughout the region. A widespread pest infestation of nymphs is expected to develop during October.

• Most of this region received moderate (20–40 mm) total rainfall in each month during May–August. Vegetation in locust habitats in green.   

Forecast 

• Swarms are likely to have laid in localised areas in the Lake Victoria–Coombah, Wentworth–Pooncarie, Menindee–Ivanhoe–Hillston, Clare–Balranald and Willandra Lakes–Euston areas during April and early May.

• Hatching of the majority of nymphs will commence in the Menindee–Ivanhoe area from mid-September and in the Balranald–Wentworth area from the start October. Earlier hatchings are likely on sandy exposed soils and hatchings will continue for several weeks.    

Risk(s)

• There is a high probability of a pest infestation of nymphs occurring in late September and October, with Bands developing in many locations.

• There is a risk of localised damage to cereal and other crops in the southern part of the region during October.    

All locust activity should be reported to your Livestock Health and Pest Authority or Primary Industries, Industry & Investment NSW.
A toll-free call to the APLC can be made on 1800 635 962. An answering machine is attached for after-hours calls.

 

QUEENSLAND

Situation in August and forecast to mid-October 2010

Southwest

Barcoo, Bulloo, Quilpie & Diamantina Shire

Locusts and conditions

• Adult population density and the number of swarms declined in Bulloo Shire during late autumn. The extent of swarm egg laying in autumn was difficult to estimate because of limited access at that time. Localised high density nymphs could develop in some areas during September. A very low density adult population was identified during early surveys.

• Early September surveys in Bulloo, Paroo and Quilpie Shires identified occasional Isolated density adults and Present density early-mid instar nymphs.

• No activity was recorded at the Birdsville or Nooyeah Downs light traps during August.

• There was widespread heavy rainfall (>40 mm) throughout most of the region in late July. Vegetation in habitat areas remains green.

Forecast

• The limited survey of this region at the start of September did not detect any significant nymph population. However, access was restricted to sealed roads and there may have been localised high density nymphs in some other locations. Habitat conditions are suitable for nymphal survival and rainfall during July may have initiated breeding and some low-medium egg laying.

• An increase in adult population is possible during September and October, following fledging of nymphs from late autumn or early August laid eggs.  

Risk(s)

• There is a moderate probability that some egg laying occurred in favourable habitat areas in this region in late autumn or winter, which could result in a medium density adult population during the forecast period.   

Locust activity should be reported to Biosecurity Queensland (Queensland Primary Industries and Fisheries). A toll free call to the APLC can be made on 1800 635 962. An answering machine is attached for after-hours calls.

Central West and Northwest

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

Locusts and conditions  

• Population density was low in areas surveyed during August and early September.

• Surveys in early August and the start of September in Longreach, Blackall-Tambo and Barcaldine Regional Council areas identified only occasional Isolated density adults in the Tambo area.

• There were moderate rains (20-40 mm) in Boulia and Winton Shires, and throughout the Central west during May. Areas east of Longreach received moderate total rainfall during August. Vegetation in habitat areas was mostly dry in grassland areas in early September.  

Forecast

• No evidence of a significant spring generation of nymphs was detected in surveyed areas. However, there could be localised areas of medium density fledging nymphs during September or October in southern areas of this region.   

Risk(s)

•  There is a low probability of a large population increase during the forecast period.     

Central Highlands

Central Highlands and Isaac Regional Council

Locusts and conditions

• Population density is likely to have remained low during winter and there have been no reports of locust activity.

• There were several rainfall events during August which brought total rainfall for the month to 100 mm in some locations.

Forecast   

• The heavy rainfall during August will produce a pasture vegetation response and may initiate some low density localised egg laying. This could produce nymphs in late September and a possible increase in adult numbers at the end of October.     

Risk(s)

• There is a moderate probability of localised increases in population level during October.          

South Central Queensland and Darling Downs

Balonne, Murweh and Paroo Shire. Roma, Dalby and Goondiwindi Regional Council

Locusts and conditions

• Population density in this region remained generally low and there were no reports of locust activity.

• Survey was conducted in parts of Roma Regional Council and Murweh, Paroo and Balonne Shires in early August. There were Isolated–Scattered density adults in the Roma–St George area, but Numerous density adults were recorded near Roma. Present density early instar nymphs were detected at one location south of Cunnamulla.

• Rainfall total for July was >50 mm in areas south of St George, while areas north of St George received > 50 mm during August. Pasture vegetation is green in most areas.   

Forecast

• While population density was generally low in this region during August, the frequency of detection in the Roma area was higher than in other regions surveyed. Nymphs in the Cunnamulla area indicate some low density egg laying in late autumn or winter. Vegetation conditions are suitable for nymphal survival and rainfall during August could initiate further breeding and egg laying.

• If breeding of the local population occurs during September, a nymphal generation could be produced from late September, possibly at medium–high densities in localised areas.

• Some nymphs may appear in Murweh or Paroo Shire during August–September, but a continuing low density population is likely in most Shires and Council areas during spring.   

Risk(s)

• There is a moderate probability of some nymphs developing during September and an increase in population level to medium densities in October.    
              

Locust activity should be reported to Biosecurity Queensland (Primary Industries & Fisheries). A toll free call to the APLC can be made on 1800 635 962. An answering machine is attached for after-hours calls.

VICTORIA

Situation for August and forecast to mid-October 2010

Locusts and conditions

• Locust swarm activity increased across northern Victoria from March 2010 and persisted into June in some areas. Widespread and repeated egg laying by swarms produced a very large number of dense egg beds during April and May. Further immigration and southward migration within Victoria resulted in an increase in swarm numbers, and reports as far south as Horsham, Toolondo and Stawell. A major pest infestation of nymphs is expected to develop in October and November.

• Areas of highest intensity swarm activity and egg laying were Mildura–Ouyen–Sea Lake, Swan Hill–Boort–Wedderburn, Kerang–Mitiamo–Rochester and Hopetoun–Horsham. More sporadic egg laying occurred in areas along the Murray River east as far as Numurkah, around Bendigo–Elmore, Shepparton and as far east as Tungamah.

• Examination of eggs from Northwest Victoria by DPI Victoria and APLC staff identified a pattern of late embryo development stages from sites in sandy soils, and of earlier embryo stages in loam or clay soils.

• Most areas in these regions received moderate (20–40 mm) total rainfall for May, June and July, and total rainfall >50 mm during August. Pasture vegetation will to remain green in September and October.           

Forecast

• The majority of eggs laid during late March and early April would have entered diapause and ceased development during winter. However, the proportion of non-diapause eggs laid increases during April and nearly all eggs laid during May do not enter diapause, but continue developing slowly at temperatures above 16^o C. Eggs are often laid near the soil surface during autumn and non-diapause eggs in sandy soils in exposed locations developed past the mid-embryo stage by winter. Eggs in sandy soils are likely to commence earlier than forecast dates in the table.

• The lower than average temperatures recorded during July and August, along with continued rainfall, has resulted in slower development of eggs laid in heavier soils. The result of these variations in different soil type and different vegetation densities is likely to be protracted hatchings extending over September and October, and nymphs at a range of development stages during October and November. The extended period of egg laying from late March to June will also influence the stages of egg development and hatching dates in spring.

• Hatchings are likely to commence in mid-September in the Mildura–Ouyen area and continue into early October, and in early October around Swan Hill. Hatchings in areas south and east of Echuca will commence in mid-October, around Bendigo–Wedderburn from mid-October, while in the Horsham area most hatchings are likely in late October.

• High soil moisture content as a result of regular rainfall during winter and at the start of September will ensure that hatchings will not be delayed by quiescence induced in dry conditions. Dense crop and pastures may retard the increase in soil temperatures occurring in native pastures and lead to later hatchings in some areas.

• The very green ground vegetation conditions will continue to provide adequate food for locust nymphs during October, but in some cases very dense vegetation and moist conditions could inhibit growth and survival of early instars.

• Swarm development is likely to occur in late November and December after the fledging of surviving nymphs. 

Risk(s)

• There is a high probability of a serious widespread pest infestation of nymphs in Northwest and North Central Victoria developing in October and November.

• There is a risk of localised damage to cereal and other crops during October and November.            

Locust activity should be reported to the Department of Primary Industries, Victoria. A toll-free call to the APLC can be made on 1800 635 962. An answering machine is attached for after-hours calls. 

SOUTH AUSTRALIA

Situation in August and forecast to mid-October 2010

Far North, Northwest & Western Agricultural region

Locusts and conditions

• Swarms developed in parts of the Far North region in early April, but densities declined following emigration. The extent of any dense egg beds in this region is unknown, but sporadic egg laying is likely to have occurred. Egg laying occurred in late March on the eastern Eyre Peninsula and hatchings will commence from late September.

• Hatchings were reported from the Commodore Swamp area, near Parachilna, on 4 September.

• No activity was recorded in the Dulkaninna or Oodnadatta light traps during August.

• The Northwest region received moderate rainfall (20–40 mm) during May and August, the Far North received total rainfall >50 mm during July in some areas, and moderate rainfall during August. The northern Eyre Peninsula received moderate totals in June, July and August. Vegetation is green in most areas of these regions.     

Forecast

• Rainfall during April around the northern Flinders Ranges and Roxby Downs areas could have prompted some swarm egg laying activity in late April, which could produce localised Bands during September.

• Hatching of any eggs laid in the Moomba–Innamincka, Marree–Lyndhurst and the northern Flinders Ranges will occur in early September and may continue over several weeks. Some localised Band development is likely during September, particularly in habitats associated with drainage lines.

• Hatchings on the Eyre Peninsula will commence in early October and small localised Bands are likely to develop during October in the Kimba–Buckleboo area during October.     

Risk(s)

• There is a high probability of localised small Bands developing on the eastern Eyre Peninsula during October.

• There is a moderate probability of a significant infestation of nymphs and Bands forming in areas around the northern Flinders Ranges and of localised Band development in areas further north in the Far North region.
  

 Northeast, Murray Valley & Southeast region

Locusts and conditions

• Swarms developed from nymphal Bands in the southern Flinders Ranges at the start of April. Migrations from further north in South Australia and from western NSW brought many swarms into the southern Northeast and Murray Valley regions, extending into the Southeast region. Widespread high density egg laying occurred during April and continued in May, with many reports from the Murray Mallee district and from Pinnaroo and Bordertown in the Southeast region. Southward migration also resulted in swarms extending from Hawker to Peterborough and in the Port Augusta–Wilmington area in mid-April, with reports as far south as Kadina on the Yorke Peninsula in late April. A serious widespread nymph infestation is expected in spring.

• Early hatchings were reported from several locations near Loxton in early September.

• Most areas in these regions received moderate (20–40 mm) rainfall totals for May, June and August, while areas south of the Murray River received >50 mm during August 

Forecast

• The majority of eggs laid during late March and early April would have entered diapause and ceased development during May. However, the proportion of non-diapause eggs laid increases during April and nearly all eggs laid during May do not enter diapause, but continue developing slowly at temperatures above 16^o C. Eggs are often laid near the soil surface during autumn and non-diapause eggs in sandy soils in exposed locations developed past the mid-embryo stage by late autumn. Eggs in sandy soils are likely to commence hatching earlier than forecast dates in the table and the hatchings reported in the Riverland are likely to an example of this.

• The lower than average temperatures recorded during July and August, along with continued rainfall, has resulted in slow development of eggs laid in heavier soils. Variations in soil type and vegetation densities is likely to result in protracted hatchings extending over September and October, and nymphs over a range of development stages during October and November.

• The majority of eggs should hatch from mid-September in the areas around Hawker, Orroroo and Port Pirie, and in late September in the Burra¬¬–Morgan area. In the Renmark–Waikerie area hatchings are likely to extend from mid-September in sandy soils through to early October.

• Hatchings will occur progressively later in more southerly areas, with the majority of hatchings at the start of October in the Pinnaroo area, and after mid-October around Keith.

• Based on the number of swarms and the duration of their activity, the areas where Bands are likely to develop in high numbers include the Riverland and Murray Mallee, extending west to Morgan and south to Karoonda, and also the Pinnaroo-Lameroo area. Less intense hatchings are likely in the Bordertown Keith area, but some Band development is likely to occur.

• In the Northeast region the highest intensity of hatchings and Band development is likely in the Hawker–Quorn–Peterborough. Some Bands are also likely in the Jamestown–Burra-Morgan area and to the north and south of Parachilna–Yunta.

• Fledging of surviving nymphs will commence in late October in northern areas through to mid-November in the south. Swarm formation is possible in the weeks after fledging. 

Risk(s)

• There is a high probability of a significant nymphal infestation developing in farming districts of the southern Flinders Ranges, extending south to Orroroo, Peterborough and Jamestown.

• There is a high probability of a serious nymphal infestation developing in the Riverland and Murray Mallee districts during October and November.

• There is a high risk of localised damage by locust nymphs in cereal and other crops during October and November. 

Locust activity should be reported to Primary Industries & Resources, South Australia.
A toll-free call to the APLC can be made on 1800 635 962. An answering machine is attached for after-hours calls.

Map of Rainfall distribution 

 

Place Name Key for Rainfall Distribution Map

Queensland		Northern Territory		New South Wales
Bo	Boulia	AS	Alice Springs	B	Bourke
Br	Brisbane	TC	Tennant Creek	BH	Broken Hill
Bi	Birdsville			Du	Dubbo
Ch	Charleville	South Australia		Ha	Hay
CT	Charters Towers	Ad	Adelaide	Iv	Ivanhoe
Em	Emerald	CP	Coober Pedy	Na	Narrabri
Hu	Hughenden	Ma	Marree	Sy	Sydney
JC	Julia Creek	Oo	Oodnadatta	Ti	Tibooburra
LH	Lawn Hill	PA	Port Augusta	Wy	West Wyalong
Lo	Longreach	Yu	Yunta
No	Normanton
Qu	Quilpie	Victoria
SG	St. George	Ho	Horsham
Ur	Urandangi	Me	Melbourne
Wi	Windorah	Mi	Mildura

Glossary of terms and abbreviations used in the Locust Bulletin

Where higher densities occur a large proportion of the regional population is concentrated in small areas with lower densities elsewhere, so the high densities cannot be extrapolated across the area of an entire region. Typically a range of density classes is found within surveyed regions and higher densities occur where habitat conditions are favourable. More detail is available about terms and descriptions used here.

Nymph Densities	Number per m2
Present (P)	1        -    5
Numerous (Num)	6        -    30
Sub-band (SB)	31      -    80
Band (B)	>   80
Adult Densities	Number per m2	Number per hectare
Isolated (Iso)	-    0.02	< 200
Scattered (Scat)	0.03   -    0.1	>200   -   1000
Numerous (Num)	0.2     -    0.5	>1000  -  5000
Concentration (Conc)	0.6     -    3.0	>5000  -  30,000
Low Density Swarm (LDS)	4.0     -    10	>30,000 - 100,000
Medium Density Swarm (MDS)	11      -    50	>100,000 - 500,000
High Density Swarm (HDS)	>   50	>500,000
General Density Classes	Nymph Densities	Adult Densities
very low, occasional	Nil-Present	Nil-Isolated
low	Present-Numerous	Isolated-Scattered
medium	Numerous-Subband	Scattered-Numerous
high	Bands	Concentration-Swarms

Reporting locust infestations

It is important that all locust activity is reported as soon as possible to your Department of Primary Industries (Agriculture) or to the Australian Plague Locust Commission.

State	Authority to report locust infestations to
New South Wales	Livestock Health and Pest Authority (LHPA) or Primary Industries, Industry & Investment NSW
Queensland	Biosecurity Queensland, Queensland Primary Industries & Fisheries
South Australia	Primary Industries & Resources South Australia (PIRSA) Plant Health
Victoria	Department of Primary Industries, Victoria - Plague Locust information

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

Free call (Canberra) - 1800 635 962 (24 hours)
Fax (Canberra) - (02) 6272 5074
Email: Locust Report

 

Forecasting Districts used in the Bulletin

General regions referred to in the Bulletin

Location of APLC light traps (black circles).
Locust habitat areas shaded.