Biosecurity network interventions

  • Auckland Harbour. Image - Pike Brown

    Auckland Harbour. Image - Pike Brown

  • A beekeeper inspects a hive. Image - Linda Newstom-Lloyd

    A beekeeper inspects a hive. Image - Linda Newstom-Lloyd

  • Salad field. Image - © Plant & Food Research

    Salad field. Image - © Plant & Food Research

Project 2.1

Leader: Professor Phil Hulme, Lincoln University

Mission Statement

Entry and spread of pests, weeds, and pathogens into NZ is a major cause of the decline of key components of NZ’s biological heritage, including the profitability of agricultural output, access to export markets, and the population viability of native and taonga species.


A major biosecurity challenge is the effective containment and management of threats from pests, pathogens, and weeds following their establishment in New Zealand. The determinants of spread through New Zealand of pests, weeds, and pathogens following an incursion are poorly understood. For many biosecurity threats it is recognised that human-assisted dispersal plays a critical role in their spread.

There are considerable economic, environmental, and social benefits to containing outbreaks and actively slowing pest spread before impacts can be fully realised and widespread management is required. For example, a 2-year delay to the arrival of didymo to the North Island would represent a cost saving to New Zealand of between $34.5m and $167.9m. As a result, a key priority in the New Zealand Biosecurity Science Strategy is “better understanding of the routes and mechanisms by which damaging pests and diseases can disperse within New Zealand. Tools and methods to trace incursions back to pathways to learn from experience, and forward to better understand how pests and diseases spread, will be very valuable”. Such movements must apply knowledge of ‘dispersal networks’, which can be modelled mathematically and applied to any organism in any situation.

Research in this project will focus on the relative roles that four different human-assisted networks, both individually and together, may play in the spread of pests, weeds, and pathogens: (1) The plant nursery network: the movement of live plants through professional nurseries is known to be an effective means to disseminate plant pathogens, invertebrate pests, and weeds. (2) The livestock transport network: livestock movements are known to play a critical role in the spread of animal diseases (e.g. FMD), ticks, and parasites. (3) The freshwater recreational user network: New Zealand lakes are widely recognised as hubs for potential invasion via recreational users moving weeds and invertebrate pests. (4) The natural area visitor network: the increasing penetration into natural areas of visitors provides new routes for the entry of pests, weeds, and pathogens into areas of high biodiversity value, and have been responsible for introducing and spreading pathogens (e.g. Phytophthora, myrtle rust) and weeds.

To develop and implement modelling tools for freight movement, nursery trade, livestock movement, and recreational travel networks to mitigate human-assisted pest spread. These tools will permit:

  • Mapping out the generic patterns of likely introduction and spread in New Zealand
  • Identification of critical points in networks to target cost-effective intervention and surveillance
  • Increased traceability such that an outbreak could be traced back to the supplier or importer.
  1. What are the attributes of different networks that facilitate invasive species spread and establishment?
  2. Do networks span management boundaries such that a multi-stakeholder response is required?
  3. How will network structure change over time and what are the consequences for biosecurity?
  4. How can an understanding of networks help focus surveillance efforts and intervention strategies?

Tahuri Whenua is a national Māori collective aligned to the horticulture sector with a particular interest in vegetable and food production. The collective is effectively a volunteer organisation that functions under cultural parameters and operates using first principles which associate Māori values to all their activities. The maintenance of a collection of plant materials (germplasm, seed, living plantations accessed for cuttings etc.) is undertaken both as a repository of economic plants for Māori and also as a hub for the distribution of plant material to ensure continuity of production and access for future generations. The Māori community generally access these materials through the collective for a broad range of purposes: home or marae gardens, community gardens, supply opportunities for special functions (e.g. marae or religious anniversaries), kura and schools and more. This project will look at the element of exchange of crop material (seed or cuttings as in kumara or taewa) through the collective hub with a view to better understanding the role of key foods in Māori society, purpose of exchange, volume, and geographical/spatial effect. The understanding gained will allow a better perspective of the role of tradition and culture in the movement of plants and foods throughout Māori society and how this practise can be understood with a view to minimising the unwitting distribution of plant related issues through cultural processes. From a network perspective the issues this component will address include:

  1. The major providers and recipients of different horticultural taxa within your network, are these flows symmetric or asymmetric, are some members major hubs for distribution nation-wide while others supply material only locally?
  2. The fate of material exchanged e.g. is it consumed within a short period, stored locally for any length of time or planted?
  3. How the structure of these flows of goods vary seasonally and with the specific products e.g. is the pattern of kumara exchange very different from potatoes?
  4. Perceptions among providers and recipients of how movement of horticultural material might spread pests and diseases, their own experience of these problems and their gut feelings as to whether pests have been introduced through such exchanges.
  5. Attitudes towards mitigating pest outbreaks e.g. MPI vs traditional approaches to containment, importance of horticultural hygiene, development of awareness of problems

The team will be led by Professor Philip Hulme (Lincoln University), and brings together high-profile university academics (including two FRSNZ) with senior CRI colleagues to integrate fundamental and applied aspects of applying network models in biosecurity across a range of threats. Links will be made to the Bio-Protection as well as Complexity (Te Pūnaha Matatini) CoREs and the Plant Biosecurity CRC.

Dalziel P & Hulme PE (2016) A Socioeconomic Research Plan for Evaluating Possible Interventions in New Zealand Biosecurity Networks. Research Report No 338 Agribusiness and Economics Research Unit, Lincoln University

Ganley B (2016) Natural area visitor network: Suitability of existing pathogen data and opportunities for new data collection to parameterise a natural area visitor network model. Scion Research Output 57827.

Ganley B (2016) Plant nursery networks: Suitability of existing pathogen data and opportunities for new data collection to parameterise a plant nursery network model. Scion Research Output 57718.

Hidano, A., Carpenter, T. E., Stevenson, M. A., & Gates, M. C . (2016). Evaluating the efficacy of regionalisation in limiting high-risk livestock trade movements. Preventive Veterinary Medicine 133: 31 – 41.