- Bioeconomy Science Institute of New Zealand, Scion group, Titokorangi Drive, Private Bag 3020, Rotorua 3046, New Zealand
- Oregon State University, Corvallis, Oregon, USA
- Bioeconomy Science Institute of New Zealand, Scion group, 19 Ellesmere Junction Road, Lincoln 7608, New Zealand
Kauri dieback disease, caused by the soil-borne oomycete pathogen Phytophthora agathidicida, has spread through much of New Zealand’s kauri (Agathis australis) forest, killing thousands of trees. However, whether kauri dieback affects the broader biological community in kauri forests is largely unknown. Here we test whether dieback of kauri trees affected ecologically important beetle communities by sampling beetles using flight-intercept and pitfall traps at three pairs of symptomatic (widespread dieback of kauri trees) and asymptomatic (little or no dieback) forest sites in Waitākere Ranges Regional Park. We collected 4366 individual beetles from 377 species and found that beetle abundance and species richness were significantly lower (34% lower abundance and 19% lower species richness) in symptomatic sites than in asymptomatic sites, whereas beetle diversity and community composition showed no significant differences. The lower abundance and species richness observed in symptomatic sites were consistent across feeding guilds and not just those directly associated with living or dead kauri trees, suggesting that the changes in beetle abundance and richness may be related to environmental changes caused by the loss of dominant canopy trees rather than the loss of kauri trees specifically. Our study presents early evidence that kauri dieback disease may have impacts that extend beyond the host species. As the disease progresses at local and regional scales, long-term monitoring of a broad range of taxa will be required to fully evaluate the impacts of kauri dieback on insect communities, as well as any direct impacts on kauri-specialist species and ecosystem functioning.