Biocontrol for eucalyptus tortoise beetle

02 October 2018

By gum: tiny wasp may protect mighty eucalyptus trees. We're considering an application to release a parasitoid wasp to control the eucalyptus tortoise beetle.

Photo of Eucalyptus tortoise beetleScion, the Crown Research Institute focused on research, science and technological development for the forestry and timber industries, has lodged the application.

“The Australian eucalyptus tortoise beetle causes significant damage to susceptible species of eucalypts. Its larvae feed voraciously on eucalyptus leaves for three weeks before pupating. Adult female beetles also feed heavily as they develop,” says our General Manager of Hazardous Substances and New Organisms, Dr Fiona Thomson-Carter.

“According to the applicant, the beetle costs the forest industry $1.0-$2.6 million a year in chemical control costs. It estimates that effective biocontrol could prevent $7.2 million in annual losses caused by impaired tree growth and yield attributable to the eucalyptus tortoise beetle.”

Farm foresters and owners of moderately-sized eucalyptus plantations cannot afford aerial spraying, so biocontrol is their only realistic option to combat damage done by the beetle, Scion notes.

“Eucalyptus trees are grown in New Zealand as a source of products such as woodchips for paper and cardboard manufacture, lumber, and durable poles which do not require preservative treatment,” Dr Thomson-Carter says.

“Scion notes around 90 percent of tortoise beetle larvae survive into adulthood. But if a larva is attacked just once by the parasitoid wasp, survival drops to just 10 percent.”

The wasp is harmless to humans.

New Zealand has no native beetles of the same type as the eucalyptus tortoise beetle, and no native eucalyptus species, Scion says. Its laboratory tests suggest the risks to non-target related native and beneficial beetles appears to be very low. It has discussed the application with various Māori groups.

Public submissions on this application open on Tuesday 2 October and close on Wednesday 14 November 2018.  

Read the application documents and make a submission

Photo: The eucalyptus tortoise beetle Paropsis Charybdis. Credit: Jon Sullivan