The role of human-assisted networks in the spread of biosecurity threats

In April 2000 the Varroa mite was discovered in beehives in Auckland. For several months authorities worked to stop the spread of this external parasite of honeybees that threatens the viability of hives.

Yet, despite the best efforts of government and industry, the mite spread across the Cook Strait and by June 2009 authorities conceded that getting rid of the mite in New Zealand was no longer a realistic option.

“Varroa highlighted that successful containment of incursions requires an understanding of how humans, in this particular case beekeepers, can inadvertently spread pests over long distances within New Zealand,” says Philip Hulme, Professor of Plant Biosecurity at the Bio-Protection Research Centre, Lincoln University.

A better understanding of the human-assisted networks that underpin the spread of biosecurity threats, such as Foot and Mouth Disease, kauri dieback, didymo and velvetleaf, is a critical missing piece in managing biosecurity risks once they have reached our shores.

“In New Zealand we are very good at border security and stopping known pests from getting into the country, but we have been less successful at containing the spread of pests across the country once they arrive,” Philip says.

Philip is the lead scientist on the Biosecurity Network Interventions Project that for the first time brings veterinary scientists, plant pathologists, ecological modellers and ecologists together to address the role humans play in the post-border spread of pests, weeds and diseases.

He highlights that, “fundamentally pests do not spread out from their point of introduction in simple ways but do so along networks that reflect the movement by humans of livestock, horticultural plants, and boats.”

“If we had understood how far and frequently beekeepers move hives across New Zealand, as well as their motivations for doing so, it would have informed the response and undoubtedly questioned the feasibility of containing the pest to the North Island,” he adds.

Philip leads a team of scientists from Lincoln, Massey and Canterbury Universities as well as Scion, NIWA and AgResearch Crown Research Institutes. They have selected four human-assisted networks to illustrate how biosecurity responses can be improved through state-of-the-art science. The four networks cover the spread of Campylobacter and other diseases in poultry flocks, how lake users move pests and weeds around on their boats and angling equipment, the role of both the formal and informal trade in live plants in disseminating plant diseases, and how visitors to our natural areas might inadvertently bring with them unwanted pest species.

“We chose these four contrasting networks to ensure we can develop important generic insights that are not industry or sector specific and highlight how network approaches provide a common approach across disciplines,” says Philip.

The researchers are using existing and newly collected data to describe the networks of nodes and links across New Zealand that characterise each network.

“We can use the network approach to not only forecast what situations might occur in the future but also understand why we have been less successful in the past.” The project team is working closely with important end-users including the Ministry of Primary Industries, Department of Conservation, Regional Councils, Fish and Game, New Zealand Plant Producers Incorporated and the New Zealand Poultry Association.

The research team also incorporates Maori perspectives by examining the movement and sharing of horticultural produce through the Tahuri Whenua network run through Massey University. In addition, the Agribusiness and Economics Unit at Lincoln University will provide economic perspectives, particularly regarding the cost effectiveness of any interventions.

“By understanding these networks we can effectively have the right kind of science post-border that we already have pre-border so we can build our science capability for incursion response to the same level as we have for prevention,” Philip says.

“There are few research projects in New Zealand that bridge such a range of disciplines in the biosecurity sphere – animal, plant, productive and non productive. There is much to be gained from people who face common challenges sharing ideas and using a common approach to manage problems.

The project will receive a total of $2,300,000 over 5 years.