Keep an eye out for cockchafers, native budworms and diamondback moths

In the June edition of PestFacts WA, released by DPIRD, native budworms were recently caught in surveillance traps at Maya, Nabawa and Spencers Brook.

They are looking for growers and consultants from Esperance to north of Geraldton to participate in their native budworm moth trapping program starting soon.

Once the traps are set up, volunteers will need to check the trap weekly, count the number of moths and report the results.

Moths typically migrate into agricultural regions in late winter and spring, but their arrival is unpredictable.

In 2024, native budworm flights began earlier than usual in the Geraldton port zone, highlighting the need for effective monitoring.

Weekly moth trapping data provides pulse and canola growers with an early warning of moth arrival and the likely risk of native budworm caterpillars appearing in crops in the weeks following.

By tracking weekly moth counts, growers and agronomists can optimise their field inspections for caterpillars, ensuring timely interventions.

However, moth numbers alone are not a reliable predictor of caterpillar infestations, with sweep netting remaining essential for accurately determining caterpillar numbers.

Large moth counts do not always equate to large caterpillar numbers as predators, parasites and weather conditions can influence survival rates.

The moths lay their eggs during August and take at least two weeks to reach five millimetres before they are detectable through sweep netting.

It takes about seven weeks from the egg stage to reach the fully-grown caterpillar stage, which is the most damaging to grain crops.

Diamondback moths (DBM) have also been recently caught in surveillance traps in Howick.

At each canola site, two moth pheromone traps are installed a bucket trap for native budworm moths and a delta trap for DBM adults.

The traps are reset fortnightly after moths are counted.

When canola plants are small, they are inspected for native budworm and DBM larvae as well as pest aphids.

As the crop advances, sweep netting is used to check for native budworm and DBM larvae.

Sweep net samples are also examined for natural enemies such as hoverflies, lacewings, ladybirds and parasitoid wasps of aphids and larvae.

The leaves of larger plants are checked for green peach aphids and as the season progresses, budding, flowering and podding racemes are inspected for cabbage and turnip aphids.

Cockchafers

WA graingrowers and agronomists are being called to report occurrences of cockchafers damaging crops.

DPIRD has identified cockchafers as a risk to oat, barley and wheat crops.

Growers from Lake Grace, Kondinin, and Dumbleyung have reported cockchafer larvae damaging seedlings.

Cockchafer infestations have been an ongoing concern for some growers in the Lakes and Kondinin region, where root and crown feeding has led to significant crop damage and failures.

The number of PestFacts WA reports of crop damage due to cockchafers has increased in recent years.

The cockchafers have been difficult or impossible to control, particularly in cereal crops with foliar insecticides, and are widespread across the grainbelt.

Research trials and surveys will be undertaken by DPIRD, with co-investment from the Grains Research and Development Corporation (GRDC) on cockchafer larvae and are seeking live specimens from properties with known infestations.

In response to increased reports and severity of cockchafer damage, GRDC initiated a three-year study with DPIRD researchers to explore management strategies for pest scarab species of WA grain crops.

DPIRD research scientist Dusty Severtson said the project aimed to identify methods of managing these underground pests.

Effective management of scarabs is complicated by the diversity of species, each with distinct life cycles, behaviours, and responses to control measures.

An understanding of the species present and their life cycle could aid in being able to target larvae in the ground or adults as they emerge and mate, preventing the persistence of resident populations.

Glasshouse trials will be running until 2027.

Pest alerts for canola growers

In 2025, DPIRD's entomology surveillance team will monitor 20 canola sentinel sites across the WA grainbelt and provide near real-time alerts on emerging pest risks.

These alerts allow growers to respond quickly to pest outbreaks if required, protecting yields and saving resources.

Sentinel sites will be checked fortnightly from June to October for targeted economic pests, beneficial organisms or natural enemies, and biosecurity threats.

Key pests monitored include native budworm, diamondback moth (DBM), green peach aphid, cabbage aphid and turnip aphid.

DPIRD reported that native budworms in Maya, Nabawa and Spencers Brook have been recently caught in surveillance traps.

Those experiencing crop damage from cockchafers, particularly in the regions of Lake Grace, Kondinin, Kulin and Dumbleyung, contact Christiaan.Valentine@dpird.wa.gov.au or Dustin.Severtson@dpird.wa.gov.au to discuss or arrange a paddock visit.

Volunteers interested in having a native budworm trap on their property this season can email Rebecca.Severtson@dpird.wa.gov.au (Northam) or Andrew.Phillips@dpird.wa.gov.au (Geralton).

To report your moth trap results, contact Rebecca.Severtson@dpird.wa.gov.au

Growers and agronomists can make a report via the PestFacts WA Reporter app or email pestfactswa@dpird.wa.gov.au