Supporting pest risk assessments in natural ecosystems

This three-year project was completed in mid-2022.

Project Abstract

When a new insect herbivore species arrives in NZ it is uncertain whether it will be able to establish in natural ecosystems and feed on native plants. This project investigated whether non-native species share traits which might enable DoC and MPI risk analysts to predict whether or not the species might pose a risk in natural ecosystems.

A database of a wide range of taxonomic, biological, ecological and distribution data populated with attributes of weevils, and later, aphids was developed. Analysis showed that non-native species that feed on NZ native plants more often have other taxonomically related species present in NZ; occur in Australia; have natural distributions with climatic similarities to NZ and tend towards polyphagy.

A Random Forest model using attributes for 65 non-native weevil species correctly predicted 46 of 65 observations (71%) in separating non-native weevils that feed on NZ native plants from those that do not. Analysis of the aphid data for 134 non-native species established in NZ showed that the subfamily Aphidinae are particularly polyphagous and more likely to feed on NZ plants; are particularly likely to occur in “pristine” NZ habitats and are larger than those recorded on NZ plants in less pristine habitats. We concluded that there are attributes of non-native herbivores in these taxa that could help predict whether native plants could be at risk from new incursions.

Biosecurity outcome

• A framework that will underpin improved biosecurity risk assessment for invasive organisms in natural ecosystems based on a comparative analysis of the characteristics of invasive organisms established in natural and productive plant systems

Science outcome

• A greater understanding of the characteristics of invasive insect species that leads to establishment in natural ecosystems as well as productive systems.

Key end users/stakeholders

Implementation:  The completed framework will be used by DOC and MPI Science & Risk – Plants & Pathways, as part of their risk assessment processes, to identify biosecurity threats to New Zealand’s natural systems.

For information and publication on this and other projects, visit Zotero. 

Zotero can be found under ‘Outputs’ on the B3 homepage.