Author Archive

How does the microbiome mediate insect biocontrol?

Tuesday, September 20th, 2022

Parasitoid wasp bursting out of an Argentine stem weevil © Dr. Sarah Inwood

Dr. Sarah Inwood, is a postdoctoral researcher at Bioprotection Aotearoa based at the University of Otago.  She has always been interested in applied research that would improve outcomes for Aotearoa and its people.

Sarah says, “Growing up on a farm, I’ve always been interested in research aiming to make agriculture more sustainable, and the ways it can be improved to benefit everyone.”

Sarah’s current research, part of project 2.1: The mechanisms of microbiota-mediated protection, certainly falls in this category. Even though her research is largely lab-based at this stage, it has huge potential economic benefits for farmers and all of Aotearoa New Zealand.

Farmers lose hundreds of millions of dollars every year through damage by invasive insect pests. Sarah’s research is investigating how biological control can reduce this damage by considering both the pest and host organisms’ microbiomes. In particular, Sarah is interested in the viruses and bacteria that live within the host species and the parasite, and how these organisms influence their relationships.

Sarah is studying two examples of such insect host-parasite systems that are economically significant to Aotearoa New Zealand.

Argentine stem weevil and parasitoid wasp

The Argentine stem weevil (Listronotus bonariensis) is one of Aotearoa’s top three worst insect pests, costing pastoral farmers over $280 million dollars in lost production every year.

The weevil is native to South America and was introduced accidentally to Aotearoa New Zealand in the 1930s. Soon afterward, as the pest spread to rye grass across the country, farmers began to notice brown and wilted paddocks.

Pesticides were ineffective at controlling the weevil, and so in the late 1980s, scientists began to search for the weevil’s native enemies back in South America. They found a parasitoid wasp (Microctonus hyperodae), which they released into Aotearoa New Zealand in 1991 as a biological control. The tiny wasp, just one-third the size of your pinky fingernail, injects its eggs into the wasp, and the larvae eat the prey from the inside out, eventually bursting alien-like from the weevil’s body.

Once it was introduced to Aotearoa New Zealand, the wasp quickly took off. In many areas of the country, up to 90% of weevil hosts were parasitised. It was one of the most successful examples of biocontrol worldwide. Unfortunately, the system also turned out to be the first example in the world of a pest that evolved resistance to biocontrol. Within just seven years, national parasitism rates had declined by 44%.

Scientists were baffled. It was generally expected that, unlike chemical controls, biocontrol would evolve alongside their hosts, keeping resistance at bay. What had led to the weevil’s increased resistance to the wasp? Had the weevil changed its behaviour, or had it evolved genetic changes that helped it resist the wasp?

Sarah’s previous PhD research focused on this question by looking at the genome of the weevil to see if she could identify genetic changes that had increased the weevil’s resistance. Meanwhile, other researchers at the Bioprotection Research Centre (Bioprotection Aotearoa’s predecessor), focused on behavioural changes that might have affected the weevil’s response. Both projects also looked at differences in the weevil across its range, to see what might explain the geographic differences in parasitism rates from very high in the north to lower in the south.

The behavioural research found some changes in the ways weevils learned to avoid wasps, possibly contributing to its resistance. But the genetic work never found “a smoking gun” that conclusively showed an underlying genetic source of the resistance to parasitism.

However, Sarah’s research did uncover an intriguing finding. The parasitoid wasp carries a strange virus that it transmits to weevils when it infects them. Was this virus affecting how the weevil reacts to parasite infection?

This discovery was the beginning of an expansion of Sarah’s research to look at how viruses – and other organisms in the microbiomes of the host and parasitoid – might affect the host-parasite relationship and the species’ relative fitness. Sarah’s research now hopes to discover what impact the virus has on the wasp and what role it plays when injected into the weevil.

Sarah is also looking at bacteria in the microbiome of the weevil to determine if these bacteria play a role in the weevil’s resistance to the wasp.

Either scenario could help scientists pinpoint what has caused resistance and help make biocontrol effective again, or perhaps help create a new form of biocontrol using a virus or bacteria. This is significant because while laws about genetic modification prevent researchers in Aotearoa New Zealand from releasing genetically modified biocontrol agents, using a virus or bacteria for control is still possible.

Honeybees and varroa mite

The second insect host-parasite system that Sarah is studying is honeybees infected by the varroa mite. Unlike the Argentine stem weevil, honeybees (while not native to Aotearoa) are an economically important species, and the varroa mite transfers a virus that kills them and causes catastrophic hive collapse.

Sarah’s research is investigating whether bacteria might protect honeybees against either the mite or virus, and how viruses and bacteria all interact to affect the relationship between honeybees and mites. Although lots of research is being done elsewhere on the varroa mite given its economic importance globally, Sarah’s overall approach in studying the microbiome as an important aspect of the relationship between host and parasite is novel.

Recent advancements in genetic technology and tools are making this work possible.

Sarah says, “Part of the reason for my interest in genetics is that my mum studied this before she had kids. When she saw me take an interest in this, she was able to really foster that interest.

She’s fascinated in everything I do. Things have advanced so much, she’s always interested in how quickly we can do things that she slaved over for days.”

How can wetlands be more resilient to global change?

Tuesday, September 20th, 2022

Dr. Stephanie Tomscha

Wetlands are critical ecosystems, providing rich biodiversity, water purification, carbon sequestration, flood abatement, mahinga kai and whatu, and recreation and wellbeing. Aotearoa New Zealand has lost over 90% of its wetlands, and the restoration of some of these wetlands is needed to return these benefits to many parts of the country.

Based from Victoria University of Wellington, Dr. Stephanie Tomscha is part of a team at Bioprotection Aotearoa studying how wetlands might be restored to create resilience to global changes. They have been studying wetlands for more than four years in Wairarapa, a region where wetlands are scarce (only 2% remain), fragmented, small and largely on private property.

Stephanie, a Landscape Ecologist, is using GIS to model where new wetlands should be created in Wairarapa to maximise outcomes for native biodiversity and for local people through better water quality, more access to cultural resources, and better carbon storage.

More specifically, Stephanie’s models are also investigating where wetlands could be restored to protect the critically threatened endemic tree species, swamp maire (Syzygium maire). The species only grows in wetlands and it is culturally important to Māori as kai (it has 18 times the concentration of antioxidants as blueberries) and a natural dye for harakeke.

Like many wetland species, swamp maire declined in range because of the draining and conversion of wetlands to farmland since colonisation. However, prior May 2017 – when the fungal disease myrtle rust (Austropuccinia psidii) arrived in Aotearoa – its conservation status was ‘Not Threatened’. By 2018, its status had changed to ‘Threatened – Nationally Critical’.

Myrtle rust attacks all species in the Myrtaceae family, which is the second most prevalent family of plant species in Aotearoa. Swamp maire is particularly at risk from myrtle rust because of its fine and thin leaves.

Stephanie’s modelling includes climatic conditions such as wind, temperature and humidity, as well as features such as soil moisture and soil type, to identify where refugia for swamp maire should be located to protect it from the incursion of myrtle rust. Research in Australia suggests that valley bottoms that are protected from strong winds may be good refugia from myrtle rust, because the disease is spread by wind. Also, swamp maire only grows on the wettest soils, so it’s important that refugia are located on these soil types.

Landcare Research did similar modelling on swamp maire at a national scale several years ago and found very limited opportunities to protect the species from myrtle rust. However, more recent work suggests that there may be more potential for refugia than this work suggested. In addition, local modelling is needed to ensure the species survives in Wairarapa, as iwi want to be able to access the taonga locally, not just nationwide.

The work that Stephanie is doing for Bioprotection Aotearoa, is part of Project 1.3: Understanding the spatial dynamics of emerging threats to ecosystem health, led by Dr. Julie Deslippe. The group is more generally studying the relationship between plants and microbes, and how they affect the stability of ecosystems in the wake of global change.

The team is highly focused on myrtle species, because their prevalence in Aotearoa means that they are likely to be a large driver of ecosystem change in wetlands here. They will also study how the composition of myrtle species in a wetland affects the ecosystem’s resilience and how wetland species composition will change if myrtle species decline or disappear in the future.

Stephanie and the wider group are involving the community, especially local farmers and iwi, in their research to understand why wetlands are important to them and how this might affect their restoration. They recently published a paper showing that many local farmers are restoring wetlands on private land, because they are well aware of the benefits of wetlands, including water filtration, easier land management, and more.

Stephanie says, “I have been working on wetlands in Wairarapa since 2017, and so I have long-standing relationships with people there. Wetlands are so at risk and do so much for us. We need to look at them holistically to see the benefits and resources they provide. When we have healthy wetlands, what does that provide people and how can that help us protect them?”

Research uncovers what helps weeds invade mānuka and kānuka shrublands

Monday, September 19th, 2022

The edge of kānuka shrubland that has been invaded by weeds

Mānuka and kānuka shrublands are spread across Aotearoa New Zealand and provide important economic, environmental, and cultural benefits. They are a source of high-value honey and traditional medicines, and they provide a refuge for native birds and a nursing ground for native plant regeneration.

Unfortunately, mānuka and kānuka shrublands are also under threat from many factors, including incursions by weeds. To better protect shrublands across the country, postgraduate fellow Dr. Laureline Rossignaud is conducting research that will help us understand what factors help mānuka and kānuka shrublands resist weed invasion, and to better understand the dynamics of weed invasions through time.

This research is part of Nuku-a-rangi, Pou 3 for Bioprotection Aotearoa.  Laureline’s project 3.2 is led by Dist. Prof. Philip Hulme which aims to determine the role of landscape attributes, ecosystem characteristics, and species traits on weed incursion in mānuka and kānuka shrublands. Laureline is using large datasets to investigate the drivers for weed invasions at the landscape scale.

The main database, hosted by Manaaki Whenua Landcare Research, is part of the national vegetation survey databank which provides plant information from permanent plots in mānuka and kānuka shrublands.

The drivers that Laureline is investigating include:

  • the proportion of exotic lands surrounding the plots, which can host weeds and facilitate their incursion in the shrublands
  • the distance to the nearest roads and rivers
  • The climatic conditions at the plot (mean annual rainfall and temperature)
  • the plant community already in the plot, including the structure of the vegetation with native species richness and native plant cover across different heights.

Laureline’s research so far has found that native tree species richness is very important in helping shrublands resist weed invasions because exotic species must compete with native trees for resources. In addition, most exotic weed species are adapted to open habitats, so tall native trees also make the ecosystem resilient against invasion by limiting access to light and space.

On the other hand, Laureline’s research also confirms that factors that help weeds invade shrublands include the proximity of exotic grasslands and the fragmentation of habitats.

Laureline is now creating maps to investigate the relationship between climate and weed invasions. These maps show that shrublands on the West Coast and in the southern South Island have fewer weed invasions than shrublands in other parts of the country. This is probably because these areas are largely in national parks and they are wetter and colder than other parts of the country. Climate is significantly correlated with weed invasion in the models, and warmer climates generally help exotic species establish.

Laureline says, “I have really enjoyed making maps and looking at the distribution of exotic species. When I was building the maps, I discovered some exotic species are spreading and others aren’t, which is quite interesting. I’m now having a more detailed look at why this is happening.”

Laureline’s research over the next year and a half will work to identify which weed species are extending their ranges and invading more plots, what factors are driving this spread, and what threats the weeds pose to mānuka and kānuka shrublands.

Laureline is enjoying being part of Bioprotection Aotearoa and says, “It’s a great opportunity because such a large number of scientists are working in this space. It’s a huge network and I’m going to learn a lot from all of the other cool projects. I feel excited and lucky.”

The value of industry-based conferences and symposiums for our early career researchers

Tuesday, August 16th, 2022

Bioprotection Aotearoa would like to congratulate New Zealand Plant Protection Society which reached a significant milestone by celebrating its 75th annual conference.  This was preceded by a one-day symposium, on the theme, plants, and pathogens that keep us awake: past, present, and future threats to native species.

Held at the Christchurch Town Hall, some of our world-class academics and early career researchers from Bioprotection Aotearoa, took to the podium to share their work.

Alexa Byers, a postdoctoral fellow based at Lincoln University presented her PhD research, looking at soil health, and the anti-microbial potential of the kauri soil microbiome against kauri dieback.

“This was the first in-person conference I have attended since before Covid, so the highlight for me was catching up with other New Zealand scientists outside of my research institution again,” Alexa says.

Based at Plant & Food Research, Nicola Sullivan is a Master’s student aligned with Bioprotection Aotearoa.  She also presented her Master’s research looking at spider biodiversity in crop ecosystems.   Nicola says a highlight was “to hear several Māori researchers presentations and presenters talking about practical impacts of their research for communities.”

For one of our students, this was the first industry-based event they had attended. Alexandra Cox, a Master’s student at the University of Canterbury says attending the symposium was an eye-opening experience, particularly around the biosecurity space.

“I enjoyed the community aspect of meeting people from Bioprotection Aotearoa face to face. I did not realise how far-reaching Bioprotection Aotearoa was, and that it covered so many disciplines”

As the next generation of Bioprotection leaders, attending symposiums and conferences such as this, offer great experiences and networking opportunities for our early career researchers to advance themselves as active contributors in their field of research.

View our current cohort who are well on their way to become the next generation of bioprotection leaders.

National adaptation plan lacks clarity on what adaptation should look like for our natural environment

Thursday, August 4th, 2022

Bioprotection Aotearoa welcomes the release of the national adaptation plan but believes it falls short of providing clarity and understanding of what adaptation means concerning climate change, particularly for our natural environment.

Many of the actions in the national adaptation plan refer to the restoration and protection of indigenous ecosystems. However, the natural environment of Aotearoa New Zealand is continually adapting and changing over time.  What is not understood, is the longer-term implications of ecosystem loss, and this is where we believe more research should be directed to fill these gaps in knowledge.

Rather than focus on the protection of individual species and or systems in our natural environment, more research is required to understand the value of these ecosystems and species and how to build resilience across environmental scales.

Knowing what defines the health of a productive ecosystem is crucial to understanding how to protect ecosystems, how to undermine the persistence of undesirable components in ecosystems, and how to monitor whether sustainable ecosystem productivity is improving. In essence, a healthy ecosystem is relatively resistant to change and can also reassemble and reorganise following disruption.  This is what it means to be resilient to change.

The research of Bioprotection Aotearoa is working to understand what constitutes a healthy ecosystem, including the incorporation of mauri (life forces). The health of our plant-based productive ecosystems emerges from interactions amongst plant communities, microbes in and on plants, external stressors, and the broader landscape context at a variety of spatial scales.

This knowledge will form a baseline so that success and failure can be measured.  Without this, it is challenging to develop a long-term adaptation plan for our natural environment that will protect the life forces that exist in Aotearoa New Zealand. Although the national adaptation plan identifies understanding ecosystem baselines as a knowledge gap, there are few concrete actions identified to fill this critical gap.

Bioprotection Aotearoa believes there is a need to have an inclusive conversation as a nation to identify what we want to protect (and what that would cost), whether we are prepared to allow change and understand what that might look like. We need to develop shared goals of adaptation as a nation, including what it is about the natural environment that we value. These are questions of ethics and values that need to be discussed by citizens across Aotearoa New Zealand.

Read the full submission from Bioprotection Aotearoa in response to the draft national adaptation plan here.

Is provenance or phylogeny a better predictor of growth and survival of a soil pathogen in leaf litter?

Monday, July 25th, 2022

Exotic plants have the potential to increase pathogen inoculum that can affect native plants. New Zealand’s iconic kauri tree (Agathis australis) is threatened by disease caused by Phytophthora agathidicida, which is most prevalent in fragmented forests that have been invaded by or are adjacent to populations of exotic species. Exotic plants have been introduced intentionally (i.e., plantations and pastures) and unintentionally along the margins of kauri forests, yet it is unclear if invasive species play a role in pathogen spread.

To determine the extent to which native and exotic plant litter supports P. agathidicida inoculum, researchers performed a phylogenetically controlled detached leaf assay. They inoculated 60 native and 44 invasive species’ leaves with three isolates of P. agathidicida collected from two different geographical regions of New Zealand, measured disease symptoms and re-isolated the pathogen from infected leaves.

Lesions grew larger and faster on exotic leaves across all three isolates tested. However, pathogen recovery was not necessarily more likely from exotic leaves. In contrast, one of the three isolates grew faster when recovered from native compared with exotic leaves. Phylogeny did not predict disease expression.

This data suggests that native and exotic plant litter may be reservoirs for P. agathidicida, but reservoir potential varies among isolates. These results also support key management tools used in New Zealand aimed at reducing pathogen spread by foot traffic in fragmented kauri forests, such as hygiene stations for shoe cleaning at trailheads and boardwalks in sensitive forest areas. Further, these tools may benefit forest management worldwide, as pathogens and exotic, invasive species increase at a global scale.


National Adaptation Plan (NAP): Submission for consultation

Thursday, June 30th, 2022

The Ministry for the Environment consulted on a draft national plan to help Aotearoa New Zealand adapt to and minimise the harmful impacts of climate change.

Professor Anita Wreford prepared a submission on behalf of Bioprotection Aotearoa.

Read our submission >

Annual Report 2021

Monday, June 13th, 2022

Adobe Acrobat PDF file, 10.1 MB

Download now >

This Annual Report for 2021, is the first chapter of our story which conveys our purpose and direction.  Bioprotection Aotearoa is a National Centre of Research Excellence (CoRE) launched in July 2021.  For the next eight years, we exist to train the next generation of bioprotection leaders to deliver pioneering, multi-disciplinary research that addresses the environmental challenges facing Aotearoa New Zealand and the Pacific.

Our kaupapa (principles) is guided by a unique framework that incorporates both mātauranga Māori (Māori knowledge) and science to understand the life forces that exist within and among our natural and productive ecosystems and their relationships with each other.

This framework supports a holistic approach to developing new and innovative solutions that protect our productive and natural landscapes from pathogens, pests and weeds in a warming climate.  The outcomes support Aotearoa New Zealand to achieve intergenerational environmental sustainability.

This annual report is for people on the ground who are managing their lands, feeding communities and employing people within their rohe.  This is for the people and organisations who are trying to make a difference in conservation.  The message of our annual report conveys our philosophy to live through our values and connect with communities at the grassroots, so they may be empowered to act as kaitiaki of their whenua as we learn to adapt to climate change and manage biological incursions that are threatening our landscapes.

Bioprotection Aotearoa is well on its way to becoming a global leader in environmental sustainability. We invite you to follow our meaningful journey as we evolve as a national CoRE and progress our research literacy to support an environment with integrity, food security and resilience.

Prof. Amanda Black

Director of Bioprotection Aotearoa

(Tūhoe, Whakatōhea, Te Whānau ā Apanui)


Effector loss drives adaptation of Pseudomonas syringae pv. actinidiae biovar 3 to Actinidia arguta

Friday, May 27th, 2022

Clonally propagated monoculture crop plants facilitate the emergence and spread of new diseases. Plant pathogens cause disease by the secretion of effectors that function by repressing the host defense response.

While the last few decades have seen a huge increase in our understanding of the role effectors play in mediating plant-pathogen interactions, the combinations of effectors required for the establishment of plant disease and that account for host specificity are less well understood.

Breeding genetic resistance is often used to protect plants from disease but it is frequently evaded by rapidly evolving pathogens. Pseudomonas syringae pv. actinidiae (Psa) which causes bacterial canker disease of kiwifruit has spread rapidly throughout the world’s kiwifruit orchards, particularly those growing cultivars of Actinidia chinensis. Other Actinidia species including A. arguta display strong resistance conferred by recognition of effectors delivered by Psa.

This research explores the depth and dynamics of Psa effector recognition by A. arguta and show that there is a trade-off between losses of effector recognition by A. arguta versus the retention of pathogenicity. These findings should aid in the understanding of how to breed durable resistance into perennial plants challenged by swiftly evolving pathogens.


Order of Merit recipient Jessie Chan says agriculture industry has an accepting culture

Wednesday, January 19th, 2022

Photo sourced from Otago Daily Times

Jessie Chan is a board member for Bioprotection Aotearoa and was inlcuded in the 2022 New Years Honours list.  She became a member of the New Zealand Order of Merit for her services to dairy and agriculture.

Journalist Tim Cronshaw sat down with Jessie to discuss her achievment, and prepared an article for the Otago Daily Times.