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Tree HEALTH & RISK MANAGEMENT

The NZDFI's eucalypt health research focuses in insect pests. While there is no avoiding eucalypt pests, researchers are working on the premis that negative impacts on eucalypt productivity can be minimised. The key is in identifying sustainable techniques for managing pests as an integral part of forest management.

Research programme and methods

Our research programme has two approaches:

1. Selection for pest tolerance

We are now well into research to identify differences between species and families in terms of tolerance to insect pests currently threatening NZ eucalypts. These include Paropsis charybdis (the eucalyptus tortoise beetle) and the more recently arrived Paropsisterna cloelia (eucalyptus variegated beetle, EVB). The research has involved a significant screening programme within NZDFI's trial sites, quantitatively assessing pests and pest damage, and also parasite activity.  The aim is to:

  • identify and remove the most susceptible genotypes from unimproved material
  • retain and improve the least susceptible genotypes as part of future NZDFI genetic improvement work.

A summary of research in this area is available:

Eucalyptus resistance to paropsine beetles (Leslie Mann and Steve Pawson, SWP Technical Report 140, December 2021).

 

2. Improve monitoring and develop thresholds for management intervention

We need to be able to answer the question: "When is it worth managing pests?"

Our overall aim is to provide growers with tools and knowledge to manage pests only when economically necessary, so reducing the  cost and environmental impact of pesticide use.

Recent research updates and presentations

Check out our six-monthly Project Updates, to read about how research is progressing.

Two workshop presentations are also available:

Managing insect pests in durable eucalypt plantations (2018)

Eucalypt health: defoliation, impacts and monitoring (2017)

Paropsisterna cloelia beetle laying eggs.

Late instar Oechalia schellenbergii nymph preying on a late instar Paropsisterna cloelia larva.

 

 

 

Paropsis beetle: a major defoliator of some eucalypt species.

 

 

 

 

 

 

Enoggera parasitising EVB eggs.

 

 

 

 

 

Phenology and natural enemies of Paropsisterna cloelia and Paropsis chayrbdis in Marlborough

PhD candidate Carolin Weser is coming towards the end of her research, which will shed light on the life-cycle and natural enemies of the two main eucalyptus beetle pests in New Zealand.

As well as detailed field observations, Carolin developed two species-specific qPCR assays to detect the DNA of the paropsine beetles within the bodies of field-collected predators to confirm predator-prey associations. The molecular analysis complemented abundance data and field observations. It confirmed the Schellenberg’s soldier bug as the most abundant and most active predator of paropsines.

Two young nymphs of the native Schellenbergs soldier-bug feeding on-Pst.cloelia late-instar larva.

 

More details of Carolin's research can be found in our Project Updates (e.g. Project Update January-June 2023).

Carolin is also an award-winning photographer - all images above are © Carolin Weser.

Key researchers

Associate Professor Steve Pawson leads the NZDFI eucalypt health team at the School of Forestry.