Strengthening cultural and biological management of pests and diseases in apple and pear orchards (AP19002)

Mastrus ridens (known as Mastrus) is an effective biological control agent for the damaging pest codling moth in several countries. Mastrus has been released across Australia but there is no evidence that it has established permanent populations in the field. Recent overseas research found that Mastrus is prone to inbreeding in laboratory cultures, and inbreeding may impede field establishment. Inbreeding could therefore be an important factor in the apparent failure to establish Mastrus in Australia.

A new Mastrus colony has been established at the Catholic University of Chile and is being prepared for shipment to Australian quarantine. As part of this work, Chilean research partners have (1) undertaken genetic studies (microsatellites) on all existing Chilean colonies to assess their diversity, and (2) mixed several Chilean Mastrus lines to maximise culture diversity and overcome inbreeding. This improved colony will be shipped to Australian quarantine when Mastrus numbers are sufficient for a viable starter colony and permits and shipping arrangements are finalised.

A study is underway into the feasibility of the commercial production and sale of Mastrus. A preliminary finding is that the necessity and feasibility of commercial production and sale of Mastrus is dependent on its success as a classical biological control agent (i.e. one that establishes permanent field populations that help to control the pest year after year). Currently, research effort is directed at implementing classical biological control because this approach would generate the most favourable return on investment for growers.

If Mastrus fails to establish permanent field populations in Australia, then commercial production and sale of Mastrus, and implementation of augmentative biological control (repeated purchase and release of the agent into orchards), may become feasible. Genetic studies of Mastrus and a new importation in 2022 will shed further light on the prospects for field establishment of Mastrus in Australia.

The commercialisation and production plan, due to be completed by December 2022, will therefore make recommendations to Hort Innovation based on data from the genetic studies, preliminary results of new releases, and industry interviews.

In the past six months, the team have progressed with a range of coordination, planning and extension activities, plus the implementation of on-ground and laboratory experiments.

Orchard activities related to conservation biocontrol experiments, IPDM and soil health assessments, and lab, glasshouse and orchard experiments with Mastrus and Trichogramma commenced.

Filming to support extension activities and a small conservation biocontrol field day at the Tatura SmartFarm were possible using COVID-safe procedures.

ACT NOW

Watch these videos prepared by the project team in conjunction with the PIPS3 Program and shared via the APAL website:

• PIPS3: Strengthening Cultural and Biological Management of Pests and Diseases in Apple and Pear Orchards, 15 December 2020 (4 mins)
• Conservation biocontrol: Attracting beneficial insects to orchards, 29 March 2021 (4 mins)

Read these articles related to the project, published in Australian Fruit Grower magazine, Winter 2021 edition:

• Conservation biocontrol of pests in pome fruit orchards – is it achievable with native ground cover species? (pages 55-58)
• Optimising establishment and impact of the codling moth parasitoid Mastrus ridens (page 59)
• IPDM Community of Practice provides platform for cooperative learning and upskilling (page 60).