Primary Industries Minister Nathan Guy and Conservation Minister Maggie Barry announced last week that the pest great white butterfly (GWB) has been successfully eradicated from New Zealand – the first eradication of an unwanted butterfly population in the world.

See DOC/MPI’s original media release about declaring GWB eradicated:

This world first accomplishment has received international attention:

The pest, first seen in Nelson in 2010, posed a significant threat to New Zealand’s native and cultivated brassica plant species. It prompted a major eradication effort led by the Department of Conservation, and both AgResearch (AGR) and Plant & Food Research (PFR) provided expertise to guide the effort.

B3 Director, David Teulon says, ‘this is a great example of how expertise from a number of organisations can come together and achieve exceptional biosecurity outcomes.

B3 scientist Craig Phillips (AGR) says from the beginning it was a challenging and absorbing project to be part of.

“The eradication attempt began with a fairly unsophisticated strategy, but with B3/AGR assistance DOC continually refined it. Attempting to eradicate any pest is a lofty goal, requiring total commitment, excellent management, smart planning, effective techniques and intensive monitoring. Our team’s main focus was on providing DOC with better knowledge to enable it to target its butterfly control efforts at the right places at the right times.”

The eradication programme was assisted by AGR’s work to analyse DOC’s inspection records to determine how the butterfly’s distribution changed and to track population trends through time. They also provided advice and modelling to the eradication team about how to prioritise their activities, developed a phenology model for great white butterfly to predict its seasonality in Nelson, developed a model to estimate its relative probability of presence in different parts of Nelson, tracked female butterfly movements through genetic analysis, and mass-reared a parasitic wasp that attacks great white butterfly pupae and released them in Nelson.

PFR also supported the eradication project using their experience in managing similar pests in vegetable and forage brassica cropping systems. With support from the vegetable industry, they monitored vegetable growing areas immediately outside the incursion zone to confirm that GWB was not dispersing. They also collected many 1,000’s of beneficial insects that attacked/parasitised the related small white butterfly, and supplied these to DOC to release into infested areas to help biological control of GWB.

DOC technical advisor Chris Green says “the support from AGR and PFR, through the B3 collaboration, was superb throughout the eradication programme. I am convinced we would not have achieved eradication in the two-year timeframe without their significant contributions. Data analysis and modelling was crucial in prioritising field teams search effort leading to success”.

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