Biosecurity works: plant pathogen arrivals slow despite increasing trade

Targeted biosecurity has reduced pathogen incursion rates in New Zealand despite increases in global trade and travel.

The rate of people and goods travelling around the world has increased dramatically over the last century. Coupled with this movement is the unwitting spread of invasive species – including plant pathogens that can cause huge economic and environmental impacts. To combat this, many countries screen goods and people at their borders. But does this expensive exercise in biosecurity actually work?

Centenary Professor Richard Duncan, from the Institute for Applied Ecology, led a team of researchers investigating how the number of plant pathogens that arrived and established on economically important plant species has changed over time in New Zealand. They found that, for the 100 years from 1880 to 1980, the annual rate of pathogen arrival increased steadily in parallel with an exponential increase in import trade over the same period. Since 1980, however, the rate of new pathogen arrivals has declined, despite even greater levels of trade and travel.

“Our study shows that biosecurity targeted at preventing pathogen arrivals works. For agricultural crops, pathogen arrival rates started to deviate from import rates around the 1960’s, coinciding with greater biosecurity efforts in the agricultural sector,” says Duncan. “On the other hand, pathogen incursions continued to increase in forestry and fruit trees, where there are more pathways for introductions and biosecurity measures haven’t been as strongly targeted at preventing pathogen arrivals.”

It is difficult to quantify the effectiveness of biosecurity measures, especially for hard-to-detect species such as pathogens. This study is the first of its kind, and took advantage of the long-term record of pathogen incursions in New Zealand to look at changes over time. The work isn’t over yet, however. “The next step is to identify the pathways by which pathogens arrive, and use this information to inform quarantine measures,” says Duncan.

“This study is particularly relevant to Australia due to our reliance on agriculture, as well as potential impacts on our unique flora and fauna,” says Duncan. “We have demonstrated that biosecurity works to slow pathogen arrivals, and is something worth investing in.”

This work was a collaboration between researchers from New Zealand’s Bio-Protection Research Centre and Manaaki Whenua-Landcare Research; University of Kansas, USA; and University of Canberra, Australia. You can find out more about this study published in PLOS Biology .