Riverina the Ideal Hotspot for Locusts?

Article by: Hari Yellina (Orchard Tech)

The Australian Plague Locust Commission is keeping a close eye on locust numbers through the Riverina after recent monitoring. Across Australia, numbers are generally low, but Chris Adriaansen, head of the APLC, said in the commission’s most recent surveys there had been high numbers of adults found in parts of the western Riverina around Jerilderie and Deniliquin up to Darlington Point.

Mr Adriaansen said that while numbers through NSW were probably lower than at this stage last year, the summer generation last year failed to develop meaning problems could still emerge in late summer and early autumn. According to Hari Yellina, this year there has been good rainfall in early summer, followed by more rain in the last week or two so that means there will be a good source of food for the locust nymphs we have just seen starting to hatch recently. So, just because the numbers were lower earlier it does not mean it will stay that way.

The geography of the outbreak is also of concern, lying in the heart of a rich irrigated cropping region. Last year the worst numbers were probably a little further north and west and not so much in the irrigated cropping regions. Additionally, in pleasing news, Mr Adriaansen said the locust population across the majority of the rest of eastern Australia was low. Surveys in Queensland identified occasionally isolated – scattered-density adults in the Channel Country, Central West and Maranoa and Warrego districts, but overall the Riverina is the focus for potential concern at present.

The weak La Nina is likely to remain until early autumn, slightly increasing the chance of above-average rainfall over much of eastern Australia, although January rainfall is less likely to exceed the average. Above-average rainfall is forecast for February and March, with increased probability over the arid interior. Low densities with limited localised medium to high densities are likely in other parts of inland eastern Australia.

It is likely that band development will start from early January onwards and swarm formation will begin in early February in the Riverina district and surrounding regions. Under suitable weather conditions, some adults of the current spring generation may continue to migrate to adjacent districts and move further into adjacent interior areas.