Forest health & biosecurity

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.

Species selection for pest tolerance

We have made some good advances in research to identify differences between species in terms of their tolerance to insect pests. These pests include Paropsis charybdis (the eucalyptus tortoise beetle) and the more recently arrived Paropsisterna cloelia (eucalyptus variegated beetle, EVB). Different species vary significantly in their ability to tolerate insect browsing - not just in terms of survival but continuing to grow well at the landscape level.

PhD candidate Leslie Mann also investigated the potential for using UAVs to monitor insect damage.

A useful summary of this research is available:

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

Next we want to learn more about site x species x insect interactions, so we can better understand why insect pests can be present on some sites without causing major damage, but not so on others. Further work is also needed in different environments to understand more about encouraging natural predators  - see below.

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.

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.








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.

Recent research updates and presentations

Check out our Forest Health publications and 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)

Key researchers

Associate Professor Steve Pawson leads forest health and biosecurity research at the School of Forestry.