Increasing curl grub population to be tackled with joint $1.5 million DPIRD and GRDC research project

Increasing populations of pest scarab beetle larvae — also known as cockchafers and curl grubs — are being tackled in a $1.5 million joint research project for growers in WA’s Lakes District and Kondinin. The research will be led by the Department of Primary Industries and Regional Development and conducted with co-investment from the Grains Research Development Corporation, with the aim of providing evidence-based tools to WA growers to combat the pest. A new and unknown species of cockchafers has been detected in barley crops in the Lakes District, with reports of isolated crop damage increasing. Barley, wheat, oat, and lupin seedlings have all been targeted by curl grub this season after resulting in yield losses of five to six per cent last season. In some cases, persistent larval feeding on roots has resulted in crop losses of more than 50 per cent. DPIRD research scientist Dusty Severtson urged growers to send reports or photos of beetles and damage via PestFacts to help with mapping the spread of the curl grubs and identify the species. He said DPIRD researchers were with Murdoch University to DNA sequence samples to identify the molecular level of the species. “This will give us a better understanding of the number of species we are dealing with and to characterise or barcode new or unknown species being found in crops,” Dr Severtson said. “Cockchafers actively feed on crops roots from June to September. “While detections are typically isolated or sporadic, there have been more than a dozen reports so far this year from the Lakes District all surviving various rates of foliar insecticides — a slight increase on last year.” Identification of the grub will assist in developing effective control measures — cockchafers can be difficult to control as a result of specie diversification and subterranean behaviour. The three year project will include glasshouse and field trial to evaluate chemical and cultural methods to contain the pest. GRDC crop protection manager — West Jonas Hodgson said the management of the pest was a high priority for Lakes District growers and had been raised as an issue at recent GRDC National Grower Network forums. “Scarab infestations have been an ongoing concern for growers, particularly in the Lakes and Kondinin areas, where root and crown feeding has led to significant crop damage and failures,” he said. “The need to develop a management package was clearly evident during the western spring panel tour in 2024.” The research will form part of the $42 million GRDC National Grains Diagnostic and Surveillance initiative, led by DPIRD in WA, to detect and diagnose exotic pests and plant diseases. “By linking species-level insights with actionable control measures, this project will give growers integrated, evidence-based tools to mitigate scarab damage, enhance crop protection and reduce reliance on ineffective chemical treatments,” Mr Hodgson said. “Ultimately, these efforts will support more sustainable and effective pest management across WA’s agricultural region.” Cockchafer and beetle reports can be made by downloading DPIRD’s free PestFacts WA Reporter app or emailing a photograph and details to pestfactswa@dpird.wa.gov.au.