Locust Bulletin November 2018

The locust population level remains very low over its range in eastern Australia. Habitat conditions remained dry in most regions, limiting any opportunity for successful breeding. Most areas that received rainfall during October are drying out rapidly. Only limited surveys have been conducted, which detected very few adults and no nymphs. There have been no locust reports and no light trap detections. Separate regional summaries and forecasts are therefore not given for this bulletin.

In New South Wales, survey in the Far West region detected no locusts. There was moderate-heavy rainfall (20->40 mm) in the Far Southwest and Central West regions during the first week of October. There were light–moderate falls (20–40 mm) in parts of the Far West, Riverina and Central West regions, with some locally heavy storm rains.

In Queensland, survey of the Central West, South Central and Central Highlands regions identified only low density adults in the Blackall–Longreach and Injune–Roma–Taroom areas. The Central Highlands and Darling Downs received moderate–heavy rainfall during the second and third weeks of October. There was further heavy storm rainfall (>40 mm) in the Central Highlands at the end of the month.

In South Australia, survey in part of the Far North region detected no locusts and habitats were very dry. There was localised light–moderate rainfall in parts of the Northwest and Western Agricultural regions in the second and third weeks of October.

No information is available for Victoria, but locust numbers are expected to be very low. There was light rainfall (<20 mm) in the Northwest and moderate falls in the North Central region during the second and third weeks of October.

The outlook for the remainder of spring and summer is for population densities to remain low in inland eastern Australia. The Bureau of Meteorology seasonal rainfall outlook for November–December indicates continued below average rainfall and high temperatures are likely to persist in most areas of the species range. However, localised heavy rainfall events can provide breeding opportunities and subsequent nymph populations. Rainfall in the Queensland Central Highlands during October will provide suitable habitat conditions for locust breeding and a small population increase is possible in November. Given the very low current population numbers in other regions, several successful generations of breeding would be necessary to produce higher density populations.

There is a low probability of a widespread infestation developing in any region during November or summer.

2 November 2018

The autumn 2018 population level was lower than that of several recent years. This species spends the winter months in reproductive diapause, often forming swarms that occupy tree-line or woodland habitats. No swarms were detected or reported during winter or September–October. Breeding usually commences with the start of the northern wet season.

Surveys in early October identified very low density adults throughout the Queensland Central Highlands and the Roma area. Occasional adults were recorded in the Blackall area.

The repeated rainfall events in the Queensland Central Highlands during October may initiate maturation and some breeding during November. Low numbers of nymphs are likely to develop in parts of that region during December. Nymph survival will be reduced if habitats become dry.

There is a low risk of a widespread infestation developing during the remainder of spring or summer.

A low density population persisted in the southern Central Highlands and northern South Central regions of Queensland in autumn 2018.
Surveys in early October detected only very occasional adults of this species in the Southern Central Highlands. Rainfall during October has improved habitat conditions for possible breeding and low density nymphs could develop during November.

There is a low risk of a widespread infestation developing during the remainder of spring or summer.

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Locust biology and behaviour