Sustainable pest management – eucalypt tortoise beetle
Issue
- The eucalypt tortoise beetle, Paropsis charybdis, is one of the most significant pests on commercially grown eucalypts.
- Eucalypt trees are grown for pulp, timber, flooring and furniture-grade lumber, ground-durable posts, amenity, urban and farm forestry purposes throughout New Zealand.
- There is increasing interest in eucalypts due to their fast growth, high density and potential to rapidly sequester carbon. Some species offer durability, while others are excellent for, short-fibre pulp for high-quality paper.
- Eucalypt tortoise beetle was successfully controlled using a bio-control agent introduced in 1989 that targets eggs. Resurgence of this pest has occurred since 2000, due to a hyperparasite that attacks the biocontrol agent.
- To combat the renewed threat posed by the beetle and protect current forest estates, forest owners have begun aerially spraying insecticide.
- This practice increases overall pesticide use for forestry within New Zealand as prior to this, insecticide use within forestry was very low (reported as 0 mT in 2002 MfE report) and jeopardises Forest Stewardship Council (FSC) certification.
Potential cost/benefits
The eucalypt tortoise beetle is now threatening the viability of all FSC certified E. nitens pulp plantations in Southland exporting 250,000 tonnes of chip annually at a value of $24 million pa.
A project is underway to determine whether is it possible to obtain a biological control agent to control the larval stage of paropsis.
Until now, any eggs escaping parasitism have produced damaging larvae with few predators.
Research will cost $130k over two years to determine feasibility and about $1 million to release a new control agent.
Outcome
Biological control is a self-managing way of controlling pests. Success with this research will remove all the current management costs associated with paropsis.
As a consequence, New Zealand eucalypt growers can continue using E. nitens as a short-fibre resource in New Zealand, and retain their FSC certification.
