2017 highlights for Ecology Ngātahi

Post by Anna Frances Probert @AFProbert

It’s almost the end of the year, so I thought I’d take the opportunity to reflect on the achievements of the Ecology Ngātahi research group for 2017. However, please note that the following post merely highlights some of the achievements of Ecology Ngātahi – there is simply not enough space or time to cover everything!


Dr Garvey and Dr Galbraith at graduation earlier this year

We said haere mai to six new students this year: Kshama Awasthi (MSc), Andre Bellve (MSc), Zach Carter (PhD), Ben Cranston (PhD), Kathy Crewther (PhD) and Cathy Nottingham (MSc) who added to our diverse array of research interests, involving everything from remote sensing to impacts of hedgehogs! On the flip side, we had five students graduate: the wonderful Patrick Garvey and Josie Galbraith were awarded their PhDs earlier this year and Sam Heggie-Gracie, Sam Lincoln and Tom Saunders were awarded their Masters degrees. Congratulations!


More recently, we congratulated a number of our academic team who were promoted to Associate Professor. Congratulations to the new Assoc. Prof. Bruce Burns, Assoc. Prof. Margaret Stanley and Assoc. Prof. James Russell. Further congratulations must also be extended to the newly appointed Professor Jacqueline Beggs. I think a lab party is in order!

Earlier this year, we were very fortunate to have two visiting PhD students from Brazil for several months thanks to their collaboration with James Russell. Vinícius Peron de Oliveira Gasparotto and Carlos Robberto Abrahão, conduct their field research at Fernando de Noronha, an archipelago 545km of the coast of Brazil in the Atlantic. Viní’s work focuses on the endemic Noronha skink (Trachylepis atlantica), with his research investigating the biology of this poorly studied species, as well as assessing the potential risk posed to the skink population from invasive species. Carlos, on the other hand, researches the biology and impacts of a large, ferocious, invasive lizard occurring on the islands, the Tegu (Tupinambis merianae). We wish Viní and Carlos all the best in finishing their PhDs and hope they come visit again (or even better, we go and visit them).

Vini and Carlos.jpg

Carlos and Viní having some car issues, but remaining in good spirits as they travel NZ



Carolina and Margaret in Sevilla (with Lucy and Jamie)

Travelling was a theme of the year, with many members of our groups going to far-flung places as a result of conferences and collaborations. James Russell had the fortune of visiting Brazil to work on island invasives, taking the opportunity to capture what I’m awarding the “Cutest critter cuddle” for his picture with a tapir. Several members of our group, including Carolina, Margaret, Jamie and Jacqueline, spent time sipping sangria (or at least I hope they did) in Sevilla, due to their international collaborations. Carolina took advantage of the European visit to attend and present a poster at the Ecological Networks Symposium in Uppsala, Sweden. Julia Schmack and James attended the Islands Invasive Conference in Dundee, Scotland and Julia Kaplick attended the 10th International Sap Flow workshop in California in May. Later in the year Ecotas lured Bruce, Cate Jamie and Ben to the Hunter Valley in NSW, Australia, where Cate was elected President of the New Zealand Ecological Society.

James tapir

James Russell wins the annual “Cutest critter cuddle” award 2017 for his picture with this tapir

Some noteworthy research highlights from students include Josie publishing two new papers on her urban bird research, Jamie publishing on functional redundancy across agricultural intensification gradients and Lloyd Stringer with his paper on the


Jamie enjoying a well deserved beer immediately post-thesis hand in

management and eradication options for the Queensland fruit fly. A special mention of congratulations Alice, who handed in and successfully defended her thesis this year, and to Jamie, who handed in his PhD in September, and is due to defend in January 2018.


Several students including the illuminating Ellery, Carolina and myself wrapped up field work for our PhDs and are now to be contained to the lab (at least in my case) or office for the foreseeable future. On the opposite side of the PhD, Ben established his kauri drought experiment Huapai and we look forward to hearing about these forest giants deal with the stress of water shortage.

And on one final note, our group had a really fantastic year for science communication. School visits, guest writing spots, radio interviews, policy opinion panels – there was a lot going on!

We wish everyone a jolly good festive season, and happy New Year. Don’t forget to spread the word and Respect the Rahui!


Merry Christmas and a Happy New Year from us!


MeblogAnna Probert is a PhD student in the Centre for Biodiversity & Biosecurity, School of Biological Sciences, University of Auckland. She is using ants as a model to assess the risk posed by exotic invertebrates to native ecosystemsShe is supervised by Margaret StanleyJacqueline Beggs, and Darren Ward.




Rāhui to protect kauri in the Waitākere Ranges

Posted by Julia Kaplick @julekap

New Zealand kauri is one of the country’s most iconic species and of great natural and cultural importance, but this forest giant is under threat by a deadly pathogen. Kauri dieback is caused by the seemingly invisible organism Phytophthora agathidicida. The first symptoms are wilting leaves and lesions at the base of trees. Underground the fine feeding roots as well as the anchoring tap roots are rotting. Over time the infection kills the trees leaving only ghostly wooden skeletons standing.


Dead kauri tree at Waipoua forest

A recent report published by Auckland Council found that a fifth of kauri in the Waitākere Ranges Regional Park show symptoms of dieback and the picture looks especially grim along the many walking tracks. The spread of the deadly pathogen more than doubled in the last five years showing that whatever measures were taken in the past had unfortunately little effect.

Phythosanitary stations have been in place since 2008. They mostly consist of Trigene or Sterigene solution filled spray bottles and brushes to clean soil from footwear. The disinfectant kills the active zoospores of Phytopthora agathadicida, but not the dormant spores which is why it is so important to remove all soil from shoes. The Council report does however show, that the stations are not effective enough, mainly due to people ignoring them or not using them properly.


As people are the main reason why the disease spreads so quickly through the forest local iwi Te Kawerau a Maki placed a rāhui over the Waitakere Ranges. Their hope is to stop any further spread and to give the forest time to heal and recover. Auckland Council on the other hand decided to not officially close regional park. To some this might be surprising, but track closures in the past have shown, that many people just ignore them. The regional park is simply too big to enforce a complete closure. This way the cleaning station will be maintained for people deciding to go for a walk despite the rāhui. The Council does support the rāhui and several individual tracks throughout the Waitakere Ranges are closed due to dieback.

Personally, I will respect the rāhui and stay away from kauri in the Waitākere ranges and I hope many will do the same. It is for now the only way to protect kauri and preserve this iconic tree for future generations.

photo_juliaJulia Kaplick is a PhD student in the Centre of Biodiversity and Biosecurity, School of Biological Sciences, University of Auckland. She is researching the response of native trees to seasonal variation in climatic conditions using measurements of sap flow, water relations and carbon allocation. Julia is supervised by Cate Macinnis-Ng (University of Auckland) and Mike Clearwater (Waikato University). Julia is supported by funding from the Marsden Fund.  

The Beautiful Sea Creatures

Posted by Carolina Lara @carislaris

In the process of becoming half New Zealander, I have invariably found myself spending a lot of time at the beach. I grew up in a semi-deserted area of Mexico so the marine environment was unknown to me, particularly the vast seabird community. From this I’ve learnt two things, not all birds live in the forest and not all seabirds are seagulls. In New Zealand/Aotearoa, around a third of the ca. 80 species of seabirds are endemic. Among the most amazing ones we find the largest albatross in the world, the magnificent toroa; the tiny and unfortunately endangered dotterel/tūturiwhatu; the Chatham Island oystercatcher/tōrea; the Westland petrel/tāiko, and the fascinating  New Zealand storm petrel (believed extinct and re-discovered in 2003), to mention a few.


New Zealand storm Petrel

Why are seabirds important? Well as explained by Moller et al (2000), seabirds often breed in dense colonies and their abundance, high guano loads and soil burrowing makes them a “keystone species”, species that play a large role in the prevalence and population levels of other species within their environment.  Any change in seabirds abundance would likely affect important soil processes (nitrification, plant regeneration) and therefore abundance of other animal species. Most importantly, seabirds shape the ecology of terrestrial communities by acting as a link between the sea and the land because they import marine-derived nutrients into terrestrial communities.

Despite the great value of seabirds in maintaining of ecosystems, their abundance has dramatically decrease worldwide, with an estimated 70% decline over the last 60 years, representing the deaths of 230 million birds. Some of the threats seabirds face are: plastic pollution (plastic rubbish is found in 90% of birds guts), overfishing, toxic pollution, nest predation by invasive species (e.g. rats) and the effects of rising sea temperatures on their food supply. New Zealand hasn’t escaped this trend with the dotterel/tūturiwhatu and yellow-eyed penguin/hoiho making it to the news recently, not many individuals of each species are left in the wild.


Dotterel/tūturiwhatu at Martin’s Bay

Is there still hope for our seabirds? Yes, with adequate management programs to get rid of invasive species in seabird colonies, regulating fishing to avoid birds getting caught in fish nets, reducing our plastic consumption and the establishment of conservation areas we can expect a recovery in seabird abundance in the long run. For now, let’s go out and appreciate these beautiful sea creatures.


CalisCarolina Lara M. is a PhD Candidate within the Centre for Biodiversity and Biosecurity, School of Biological Sciences, University of Auckland. Her research interests focus on seed dispersal networks within fragmented landscapes. She is supervised by Margaret StanleyJason Tylianakis, Karine David, and Anna Santure.

Detecting drought with remote sensing – some preliminary results

Posted by Kshama Awasthi

Green vegetation growth is a useful indicator of drought events and vegetation indices such normalised difference vegetation index (NDVI) and enhanced vegetation index (EVI) are often used for the assessment of agricultural drought. I have been evaluating the sensitivity of these indices to detect the impact of drought on forest areas in various parts of Aotearoa New Zealand. In general, a higher NDVI or EVI value represents more healthy vegetation so I expected to see a decline in the vegetation indices during drought.

Picture1Right: NDVI values for the Hunua Ranges for the month of March

There was a slight decline in NDVI in 2013 during the drought. To confirm the role of drought in the decline in NDVI, I am using soil moisture deficit (SMD) data from NIWA. SMD is calculated using incoming daily rainfall (mm), outgoing daily potential evapotranspiration (mm) and fixed available water capacity that is the amount of water in the soil reservoir that plants can use.

picture 2 v 4

Above: Soil moisture deficit and vegetation health indices for summer months at Hunua Ranges.

As expected, the NDVI (r2=55%) and EVI (r2=65%) both show a strong relationships with SMD which indicates NDVI and EVI values are responsive to drought.


Above: Relationships between soil moisture deficit and NDVI and EVI vegetation indices for summertime at Hunua Ranges, 2006-2017.

EVI values decreased more in response to drought conditions as compared to NDVI, indicating that EVI is more sensitive then NDVI on the onset of drought conditions.

Since the relationship between EVI and SMD is stronger than the correlation between NDVI and SMD, EVI can be the better indicator of drought detection in forest as compared to the NDVI as EVI provides improved sensitivity in high biomass regions while minimizing soil and atmosphere influences.

This is the result for the Hunua Ranges and calculations for other sites are still ongoing.

kshama Kshama Awasthi is an MSc student supervised by Cate Macinnis-Ng and Jay Gao

Microchipping: A force for good

Posted by Kathy Crewther @kat_crewz

Earlier this week, a Taranaki Regional Council hearings committee recommended that feral cats be defined as cats which are “unowned, unsocialised, and have no relationship with or dependence on humans” (Taranaki Regional Council, 2017). This will please some cat lovers since submissions had been made to define a feral cat as “any cat without a microchip, collar, or harness” with some owners fearing that this could equate to a ‘licence to kill’ their wandering, microchip-free pet moggie. But it does raise the question: Why haven’t you microchipped your cat?

According to the New Zealand Companion Animal Council, 44% of NZ households have a pet cat compared to 28% with dogs, making cats the most popular pet in the country. However, while 71% of dog owners had microchipped their pet, only 31% of cat owners had done so (New Zealand Companion Animal Council Inc., 2016).

Every day, websites like petsonthenet.co.nz and neighbourly.co.nz have listings of anxious owners desperate to find their missing cats and – yes – some of them are microchipped. However, the chances of being reunited with your furry family member are much higher if people know how to find you. This means not only microchipping your cat, but also making sure you keep your contact details up to date after you register the microchip.

I have had two recent experiences which illustrate the value of the microchip. Earlier in the year, one of my colleagues took in a distressed cat that looked like he had been wandering for some time. When she took him to the vet to check for a microchip, she discovered that the cat had been missing for 5 months and had somehow found his way from Botany to Takapuna! Thanks to an up-to-date microchip registration, kitty was reunited with a very happy and grateful owner.


Distance is no object to cats who will sometimes secretly (or accidentally) hitch a lift

When a cat I had never seen before turned up repeatedly on my doorstep, the lack of a microchip did not mean a death sentence for this fluffy wanderer, but it did mean I was unable to reunite her with her owners, despite placing listings on various websites. Instead, Dorey (as she is now known) was able to be re-homed with a very caring family and no longer shows any desire to wander.


In the absence of a microchip, Dorey was unable to be reunited with her owners, but fortunately a new family was found for her

Moral of the story: microchipping is there to help protect your beloved pets and to ensure that, in the event they go missing, you are reunited with them as quickly as possible. And, at around $45-80, microchipping is one of the most affordable aspects of pet ownership. So, please, if you haven’t already done it – microchip your cat.


twitter picKathy Crewther is a PhD candidate in the School of Biological Sciences at the University of Auckland. She is investigating the management of domestic cats and their impact on urban wildlife.




Decision Report of Council in respect of submissions to the Proposed Regional Pest Management Plan and Taranaki Regional Council Biosecurity Strategy, Document number: 1952447. (October 31, 2017). Retrieved November 2, 2017, from https://www.trc.govt.nz/assets/Documents/Plans-policies/PestPlanReview/RPMP-TBS-DecisionReport2017-web.pdf

New Zealand Companion Animal Council Inc. (2016). Companion Animals in New Zealand 2016. Auckland, New Zealand.



Breaking the mowing addiction – let’s have some meadows.

Posted by Bruce Burns @BruceTracks

Why do we mow so much? In the city, our landscape norm is buildings set in areas of close cropped grass, and we are taught from an early age that regularly mowing lawns is the height of good husbandry (or wifebandry). But does it need to be so?

The mown lawn could rightly be viewed as an emblem of western civilization, and modern urban form owes much to the existence of lawnmowers. Regular mowing maintains open space around our buildings and roads and prevents ecological succession of those areas to weeds or forest. But there is a lot of lawn to mow – urban grasslands take up around 15 – 20% of Auckland (and other western cities) land area. There is also a cultural norm that seems to equate closely-mown lawns to tidiness, order, and care for urban human habitat. Mowing has become a regular activity for us, and we even instil a mowing ethos in our children with toy mowers.


Meadows in low-mow situations in Auckland provide multiple environmental and biodiversity benefits

But all that mowing comes at a cost, both real and opportunity. Publically and privately we spend millions of dollars and hours each year on mowing. Environmentally, mowing burns fuel and thereby contributes emissions to the air and pollutants to water. The opportunity costs can be estimated by considering what happens if we mow less and let lawns turn into meadows. Urban grasslands provide areas for stormwater infiltration and water retention – these ecosystem services are increased when grassland swards are deeper. As well, urban biodiversity would be enhanced. Meadow vegetation supports a greater diversity and abundance of plants, insects (including pollinators) and many other life forms. As well, wildflower-rich meadows would have psychological benefits for many urban dwellers, and they are stunningly romantic.

So, let’s experiment with setting aside areas within our cities and allow them to develop into meadows. I’m not talking about everywhere and not suggesting they won’t need some management. But I think we have a lot to gain by leaving the mower in the shed and valuing the nature that happens as a result.

bruceDr Bruce Burns is a Senior Lecturer in Plant Ecology in the School of Biological Sciences, University of Auckland. He is a plant community ecologist specialising in the biodiversity and restoration of natural, managed, and urban ecosystems.

Amazon Biodiversity Monitoring in Ducke Reserve

Posted by James Russell @IsldJames

Monitoring of biodiversity is a challenge, but visiting Ducke reserve in the Amazon I am able to see one of the gold standards for long-term biodiversity research. Satellite images reveal an oddly square 10 x 10 km forest block just to the north-east of Manaus. Here lies the Ducke scientific reserve owned by the National Institute of Amazon Research (INPA). My Brazilian colleague Carlos Abrahão undertook his early postgraduate research here and is keen to show me the reserve.


Our hike in to the central camp of the reserve is exhausting. Lying on the equator in the humid forest one only has to walk a few minutes before being drenched in sweat. As we navigate the linear track system turning at right angles appropriately, an afternoon thunderstorm threatens in the distance. As we nimbly traverse the last tree fall bridge of a stream we come upon the forest camp, and only minutes later the storm hits.


After making camp, stringing our hammocks up, darkness falls and the storm abates. Carlos takes this opportunity to eagerly search for the snakes he undertook his research upon. The best he can find is a tree snake, but for a New Zealander coming from a land without snakes, this is the perfect entry level snake for someone like me to let crawl upon themselves. Still, both I and the snake are happy when it is returned to the tree.


The perfectly square grid system the design of the RAPELD system imagined by INPA researcher Bill Magnusson. By dividing the scientific reserve in to consecutively larger squares, questions of importance to biodiversity managers can be appropriately matched to scale, whether it be the taxonomy of biodiversity in a tiny square, to forest dynamics across the entire reserve. Before entering the reserve Bill was generous enough to give me a copy of his book Biodiversity and Integrated Environmental Monitoring. It is a must-read for those interested in long-term biodiversity monitoring, especially as one lies in their hammock in the centre of the very reserve it focuses upon, listening to the cacophony of amphibians.

Originally posted on National Geographic Voices

Clever communication of ideas to generate interest in your research

As students and researchers working on long-term projects, we often have to wrangle with complex datasets. Producing thoughtful conclusions from such data is something we have been trained to do for many years. Likewise, our keen eyes have been trained to interpret conclusions when they are published within the scientific literature. But, the day will come when it is time to report information to audiences outside of the scientific community. The same jargon and quantitative results used to increase comprehension within scientific literature will likely decrease comprehension when reported to a general audience!

So, what is a solution to this problem??? My answer is to use….

snazzy visuals

Well… maybe not quite as snazzy as WordArt… but the inclusion of purposeful visuals will help audiences understand your message and also keep them engaged. Furthermore, a nice visual can always be added to a thesis or powerpoint presentation to help communicate your ideas effectively.

To bring this idea home, take a look at the images below:


memePresenting your relational database to the general public will leave you looking like the over-caffeinated, sleep-deprived PhD archetype you are trying to separate yourself from (image: http://knowyourmeme.com/memes/pepe-silvia).

The first image is of my current relational database for invasive mammalian pests throughout New Zealand’s offshore islands. The second image is of how I’ll be perceived if I try to explain it to anyone else. Although informative, the database’s complexity makes it difficult for others to understand. The time required to explain its “in’s and out’s” will ultimately take away from the message I am trying to get across. As a solution to this issue, I decided to amend my database to ArcMap as a way of making it visual (see the picture below).

arcmap pic
An ArcMap image of New Zealand’s Hauraki Gulf. The different coloured polygons and data-points represent different features of the implemented database. I think we can all agree that this is much easier to explain than the other image!

Not only is it more interesting to look at, but the visual representation of my data clearly and concisely demonstrates what is going on (it’d help if I put a legend on the figure, though. Semantics.). Doing so has helped me spatially understand my dataset, too. instead of looking at lines of code, the visual form has provided context with which assist in the identification of geographic patterns.

zachpicZach Carter is a PhD student in the University of Auckland School of Biological Sciences. He is developing eradication prioritisation models to assist in the removal of invasive mammals from New Zealand. He is supervised by James Russell and George Perry.

Taking over at Huapai (and a very wet autumn)

Posted by Ben Cranston

Forest greetings

Out with the old and in with the new: a phrase which does not apply to long-term vegetation plots. Earlier in the year, I began taking the reins at one of the University of Auckland’s scientific reserves, Huapai, in the northern Waitakeres. Apart from my primary task at the site of implementing a droughting experiment on kauri (Agathis australis), I am also responsible for overseeing the continuity of long-term monitoring operations for projects past. On rare days when there is a spare moment to soak in the surroundings, I am still awestruck by the intricacy of Aotearoa ngahere urutapu (New Zealand’s virgin forest)…


… The Tasman Tempest

Thanks to data provided by NIWA, I have at last found validation for making such claims as “the rain never stops on field days” and “mud is definitely soupier today than last time. Glad I insisted on the Wellies!” because many parts of Te Ika-a-Māui –Tāmaki Makaurau included- experienced their wettest autumns on record. Indeed, the winter up north was not as wet, but the trails never quite recovered from the “Tasman tempest” of early March making the, er, march up to the site always interesting.

NIWA Mar 2017



My outlook for spring is hopeful. The sky is already bluer, the ponga seem livelier, and though the mozzies are becoming a nuisance again, they are a welcome trade-off for fair weather. Soon the apparatus for the drought shelters will be fully installed along with the tree sensors and, as they say, we’ll be off the races on a first-for-NZ drought experiment. By summertime, the lab group will be faced with the new challenge of recruiting volunteers for tree-climbing days to take canopy-level measurements.

Post Release Evaluation – Not just an Expensive Luxury!

Posted by Hester Williams @HesterW123


Classical biological control, i.e. the introduction and release of non-native insects, mites, or pathogens to give permanent control, is the predominant method in invasive plant biocontrol. A successful biological control programme eventually reduces, or in some cases removes, the need other methods of control for an invasive species that is growing prolifically in the absence of its natural enemies. The benefit-to-cost ratio of successful control can be very high, especially when earlier successes in one country form the basis for repeating the introductions elsewhere.

New Zealand has a long history in biological control of invasive plants and is one of five countries that are very active in this field. In a recent analysis on the benefits of biocontrol in New Zealand it was found that 30 % of releases (of those that could be assessed because of sufficient passage of time) resulted in significant beneficial effects. Cases with negligible benefit (36%) included agents that failed to establish, and cases with minimal benefit (33%) included some cases where predation reduced the realized benefit of established agents.


Post-Release Evaluation

An important component of all biocontrol projects is Post-Release Evaluation, the process of assessing how successful the projects have been and to understand why they succeed, fail or achieve intermediate results, and to determine and evaluate any non-target effects. Such information would not only provide better justification for biocontrol funding, but would also inform the agent selection process for subsequent projects, assist in the improvement of pre-release screening, help to increase establishment success and provide gateways to integrating biocontrol with other management practices.

Identifying biocontrol successes

Remarkable successes have been achieved through biocontrol projects, including the

St johns wort and beetle

Chrysolina sp., one of the biocontrol agents that is contributing to the successful control of St John’s wort in NZ.

control of St John’s wort (Hypericum perforatum) which used to be one of the worst four weeds in New Zealand. This plant displaced pasture in the dry high country and poisoned stock. Two beetles that defoliate the plant and a midge that stunts growth by deforming the plant were released as part of the biocontrol programme. The lesser St John’s wort beetle was the first to be released in 1943, while the greater St John’s wort beetle and the gall midge were released about 20 years later. All three agents established and today the plant has declined to the point where it is no longer considered a problem. A recent economic analysis has estimated that the Net Present Value of introducing the beetles is between $140 and $1490 million over 70 years, a benefit to cost ratio of 10:1 and 100:1 respectively. A remarkable return on investment!


Identifying biocontrol failures

Biocontrol programmes of course do not always result in successes, and failures are inevitable. Failures include inability of released agent populations to establish, or underperformance of agents. For example, here in New Zealand, the heather beetle (Lochmaea suturalis), has underperformed as a biocontrol agent when compared with the damage it does to native heather in Europe. Post-release evaluation studies have indicated that the smaller body size of beetles in NZ, probably mostly due to a severe founder effect, resulted in higher winter mortalities and therefore underperformance of the beetle in NZ. In 2014, an effort to genetically rescue the NZ population was undertaken; more beetles were collected from Scotland and mated with New Zealand beetles. These new genetic lines of beetles were released in November 2014 and currently post-release evaluation studies are underway to confirm establishment. Future studies will compare the performance of the new and original populations. This project represents a novel approach to explore the possibility of enhancing the performance of already established biocontrol agents so that they can better adapt to the local conditions and more effectively control the target weed.

Identifying Non-target effects of biocontrol

  • Direct risk to non-target plant species (usually closely related species).
Rhynocyllis larvae

Rhynocyllis  conicus, a biocontrol agent for musk thistle in the USA, also utilizing native thistle species.

The case of the weevil Rhinocyllus conicus is particularly well known. First introduced from France to North America in 1968 to control invasive musk thistle (Carduus nutans), then widely distributed in the United States, this seed predator utilizes at least 22 native species of Cirsium in North America, including some species of conservation concern that have been shown to be seed-limited. Additional studies have found that the observed level of seed predation by the weevil to not be sufficient to limit seedling recruitment.

  • Indirect non-target effects, for example, via interactions in food webs.

A highly host plant–specific weed biocontrol agent, the tephritid fly, Mesoclanis polana, introduced into Australia to control bitou bush, is associated with declines of local insect communities. As the agent shares natural enemies (predators and parasitoids) with seed herbivore species from native plants, a study implicated locally significant competition causing negative effects on indigenous seed feeding insects.

  • Conflicts of interest.
South western willow flycatcher

The endangered south-western willow flycatcher, using an invasive species (Tamarix sp.) for nesting sites in the USA.

The proposed biological control programme for saltcedars (Tamarix spp.) in North America is associated with concern about the wellbeing of an endangered species—the south-western willow flycatcher. Originally this bird species nested in indigenous riparian vegetation. Many western riparian areas are now dominated by introduced invasive saltcedars, which the south-western willow flycatchers are now using for nesting.




Post Release Evaluation – necessary but expensive

Post release evaluation is expensive, and requires long-term funding commitments and community support. Modern biocontrol practices recognize the need for post-release evaluation of biocontrol programmes, but in the past it has been seen as ‘an expensive luxury’! This is because evaluation is often perceived as basic research with no additional benefits to the community and the funding agencies. When a project has clearly been highly successful it is unappealing to channel further resources into a former problem when so many others still require attention. Likewise, if a project appears to have failed there is little incentive to spend precious resources documenting this in more detail.

The cost of undertaking Post Release Evaluation studies has to date proven to be a major obstacle both in New Zealand and worldwide. In 2015, the National Biocontrol Collective (NBC), the major funder of the development and release of new weed biocontrol agents in New Zealand, accepted a National Assessment Protocol developed by Landcare Research to ensure some level of assessment is undertaken in biocontrol projects in New Zealand. The protocol outlines minimum standards plus further options where additional resources are available.

Role of Post-Graduate Research Programmes

This is where Universities and their post-graduate research programmes can and are making major contributions, as evaluation studies are often incorporated into their research programmes. We as post graduate students (low-paid but reasonably intelligent – or just amazing supervisors?) can indulge in detailed population and ecosystem level studies – the ultimate goal of post release evaluation. Student cartoon


My Research

Neolema adult

The focus of my study: Neolema ogloblini, a biocontrol agent for Tradescantia fluminensis


My PHD study focusses on the dynamics of small populations. Many species benefit from the presence of conspecifics but at low population densities the fitness level of individuals in the population decrease. This phenomenon is known as the Allee effect. The Allee effect can drive very small populations to extinction and can play a major role in the establishment and spread of biocontrol agent populations.

I am studying how population size, dispersal and host patch connectivity interact with the Allee effect and how this influences the establishment and persistence of the leaf feeding beetle, Neolema ogloblini, a biocontrol agent for Tradescantia fluminensis. As mentioned in the introduction paragraph, 36 % of the biocontrol programmes in NZ has negligible benefit, in many cases because of establishment failure. My studies will help us to understand why some releases of biocontrol agents result in successful establishment and why others fail to do so.



Hester WilliamsHester Williams is a PhD candidate in the School of Biological Sciences, University of Auckland and is stationed with the Landcare Research Biocontrol team in Lincoln, Canterbury. She is interested in invasion processes of both insect and plant species. Hester is supervised by Darren Ward (Landcare Research/University of Auckland) and Eckehard Brockerhoff (Scion), with Mandy Barron (Landcare Research) as advisor. Her studies are supported by a joint Ministry for Primary Industries – University of Auckland scholarship. The project is an integral part of an MBIE program “A Toolkit for the Urban Battlefield” led by Scion.