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Forestry scientists are taking a closer look at bark and ambrosia beetles to understand how these insects are helping fungi move through New Zealand forests and orchards.
Researchers from the Bioeconomy Science Institute Maiangi Taiao are identifying fungal species carried by beetles trapped in plantation forests, native bush and orchard environments. The work aims to better understand whether disease-causing fungi are being spread by beetle activity, particularly where forest systems are under stress.
“While a lot is known about the beetles, less is known about the fungi that travels with them,” task lead Darryl Herron says.
Since 2024, teams based in Lincoln, Rotorua, Ruakura, Auckland and Motueka have been working together to trap bark and ambrosia beetles and analyse the fungi they carry. The research is funded through Better Border Biosecurity and Zespri.
By combining expertise and sampling across multiple sites, scientists have identified a wide range of fungal associates linked to both native and introduced beetle species. Most are common plant fungi, but some have the potential to disrupt plantation forestry, horticulture and native ecosystems if conditions change or new beetle species establish.
Bark and ambrosia beetles interact with fungi in different ways. Ambrosia beetles actively carry and cultivate specific fungi, while bark beetles pick up a more mixed group as they tunnel through trees. Together, these beetles are associated with woody plants across plantation forests, orchards, urban areas and the native estate.
“It’s often these fungi that cause the greatest harm,” Darryl says. “Some fungal species block a tree’s ability to move water and nutrients, weaken natural defences or accelerate disease, particularly when trees are already stressed by drought, age or harvesting activity.”
The research is helping scientists assess risks to native bush, urban trees and botanical collections, as well as monitor beetle activity around orchards and forest margins. Rapid beetle breeding means populations can increase quickly, allowing fungal species to spread just as fast.
By identifying which fungi are travelling with which beetles, researchers are building a clearer picture of potential biosecurity threats and which beetle species warrant closer monitoring. This information supports national surveillance led by the Ministry for Primary Industries and industry partners, including the Forest Owners Association.
Overseas, some beetle–fungus partnerships have caused widespread forest dieback. “Our focus is understanding what risks exist here before those impacts occur,” Darryl says. “If we know which beetles can carry damaging fungi and where they’re moving, we can respond faster and reduce the risk to forests and export markets.”
Because bark and ambrosia beetles can occasionally arrive in wood packaging and untreated wood products, public and sector awareness remains important. Anyone noticing dying trees alongside heavy insect activity is encouraged to report it to the Ministry for Primary Industries or the Bioeconomy Science Institute, including photos and location details.
