@z_w_mcgrath

If you only read the title of this post, you may have thought it was referring to the green men from the show X-FILES or maybe you envisioned invasion by human immigrants making Donald Trump pull out his luxurious locks .

However, it is not the extra-terrestrials or human immigrants I am referring to but the invasive species that are costing us billions of dollars, the ones that we have helped cross our borders, the vines, mosquitoes, ants and the like that now thrive in a novel environment.

Megalopyge albicolis (a butterfly, pictured here as a caterpillar)-although not currently deemed an invasive species, I’d say it would be on some peoples ‘unwanted species list’ based on the resemblance to Mr Trump’s hair. Image by Andreas Kay (CC BY-NC-SA 2.0).

While we should be concerned about non-native species, we need to remember that some actually contribute positively to the environment and people’s every-day lives. The first example that comes to mind are those non-native species deliberately introduced to control pests to appropriate levels, commonly referred to as biocontrol agents.

The non-native species we should worry about are those that displace our native species, undermine ecological services, negatively affect the economy and threaten human health. It is these species that begin to be recognised as ‘invasive’ (the term for a non-native species causing undesirable effects) by fellow humans.

New Zealand is home to thousands of non-native species. In fact we have hundreds just from one order of insects (see Darren’s blog post).  This is coupled with growing costs of control and mitigation.  The fact is we cannot control all non-native species.  Therefore, management should use a prioritisation approach, such as managing invasive species likely to have the greatest impacts on native biodiversity.

Argentine ants have invaded parts of New Zealand and are recognised as one of the world’s worst invasive species by the World Conservation Union.  Image by Pedro Moura Pinheiro (CC BY-NC-SA 2.0)

I know what you’re thinking Mr Trump, but we can’t make them pay for their own control and building a wall isn’t going to solve the issues already in the country.

This is why as part of my Masters project I am creating an alternative method to assess the risk of non-native species. It is proposed to be used as a tool for management prioritisation for those species most negatively competing with our native species, as well improving our standards on importing and releasing biocontrol agents into New Zealand.

Zane McGrath is an MSc student in the Centre of Biodiversity and Biosecurity, School of Biological Sciences, University of Auckland. He is supervised by Darren Ward, Graham Walker and Frances MacDonald (Plant and Food Research, Auckland) examining parasitism by exotic species in native environments.

Posted by Theo Van Noort @TVanNoort

I’ve heard this frequently of late, particularly when I tell people I study wasps. It’s a widely held sentiment here in New Zealand, a loathing barely matched by feelings directed towards the infamous possum.

Of course, there is something particularly terrifying about a creature that not only stings repeatedly but can also fly (read: stings to the face, shoulders, knees and toes – no problem). Pair this with a temperament more volatile than a rest-home pumped on prune juice and you can see why wasps might have garnered this reputation.

To clarify, it’s not New Zealand’s assemblage of solitary native wasps causing such affront (read earlier blogs by Tom and Zane), but rather invasive German (Vespula germanica) and common (Vespula vulgaris) wasps. These social wasps build nests and have distinct caste systems dividing the role and function of each individual in the colony.

A German wasp attacks and kills a honey bee (Apis melifera). Beekeepers lose approximately $9 million a year solely from wasps attacking honeybees, robbing honey and destroying hives. Photo credit: Henry Bennett

These two species present an unprecedented problem to New Zealand because they thrive in competition against our “naïve” flora and fauna. Vespula wasps are generalist predators and have great ecological plasticity: they can adapt and change their behaviour to best utilise the resources available in a given environment. Long story short, they decimate invertebrate populations via predation, dominate important carbohydrate resources such as honeydew in beech forest, and probably pose a direct threat to native vertebrates like lizards and birds. Moreover, public health, recreational needs and economically important industries such as horticulture, apiculture and silviculture are also detrimentally affected by Vespula wasps. In dollar-speak: ~$130 million dollars in damage per year. 

Vespula wasps butchering a giant centipede.

Given these traits, it’s easy to understand the enormous need to develop new tools with which to control Vespula wasp populations.

Earlier this week I had the opportunity to attend an open workshop run by the Wasp Tactical Group in Wellington: Tactics and Tools to Reduce the Pain of Pest Wasps in NZ. This workshop brought together scientists and other interest groups from a range of different organisations to collaborate and update the current status and future prospects of Vespula control. Despite the variety of backgrounds within the group, everyone was unified by this desire: to reduce the immense damage caused by Vespula wasps.

Vespula wasp attacks a giant bush dragonfly (Uropetala carovei). New Zealand’s invertebrate fauna are “naive” to aggressive social insects- their evolutionary history has left them defenceless to Vespula.

Through the day we heard from the different scientists about the range of tools under development by the Bioheritage National Science Challenge  for this very purpose. These control tools include the Trojan female technique, biocontrol using mites, manipulating behaviour using pheromones and semiochemicals, and targeted chemical baits. It also includes a modelling component to understand how these different tools might be used and integrated. Further to this is developing an eradication strategy, perhaps following the tradition of mammalian pest eradications which first targeted small islands.

While acknowledging the hurdles ahead, the floor was optimistic, particularly around the success and public interest to date in Vespex . Vespex, an insecticide developed by Merchento, has proven effective for drastically reducing the abundance of Vespula wasps in areas where it is applied whilst leaving other insects like honeybees unharmed. While Vespex is by no means a silver bullet, if coupled with these other techniques still under-development we may have a good chance at “reducing the pain” of these pest wasps.

Or, in other words, killing the bastards.

Theo Van Noort is an MSc student in the Centre for Biodiversity & Biosecurity, School of Biological Sciences, University of Auckland. He is investigating the attractiveness of different lures to Vespula wasps, as well as their potential role in pollination and seed dispersal. He is supervised by Jacqueline Beggs and Imogen Bassett

Posted by Emma Bodley (Twitter @ebodley)

When you think of an orchid what usually comes to mind are the beautiful showy plants such as the moth orchids that most people have on the dining room table or in the guest bathroom.

A moth orchid, by Orchi – Self-photographed, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=3126890

In the research world these are also the same orchids that get all the attention. But the New Zealand orchid diversity is more understated, usually terrestrial green plants blending into the forest floor. As ecologists we know very little about NZ orchids in general and there are many forms that are yet to even be formally named.

Our recently published paper reveals some of the secrets about the

The greenhood orchid Pterostylis brumalis

phenology and pollination system of one native greenhood orchid Pterostylis brumalis. What pollinates them? How do their pollinators know where the orchids are? Do they use sexual deception – tricking male pollinators into visiting the flowers like some other orchid species do?

We followed the phenology of this winter-flowering orchid closely, trapped for pollinators using sticky traps and assessed the natural seed set of a population. Problem was, pollination was extremely limited in the two populations we studied. We only collected only one insect, a female fungus gnat, that had interacted with a flower and was carrying pollen. As a consequence, natural fruit-set was low, averaging only 2.6%. In contrast, when we hand-pollinated flowers we achieved 66.7% fruit-set. It remains a mystery as to what naturally pollinates this species.

One of the harder areas to investigate is the theory of sexual deception in greenhoods. Usually orchids that trick male pollinators into visiting their flowers produce a scent that mimics that of a female. We wanted to look for evidence in the flowers that this is a possible mechanism for attracting male pollinators. Studying the colour and micromorpholgy of the flower showed some interesting features. We were looking for scent glands where the scent could be released from. We found some hairs that could perform this function, but most likely guides the pollinators into the centre of the flower down to the pollen. We didn’t find sufficient evidence to prove that sexual deception is really happening in this system. There are still plenty of avenues to research to get a better understanding of orchid pollination.

Bodley, E., Beggs, J., Toft, R., & Gaskett, A. (2016). Flowers, phenology and pollination of the endemic New Zealand greenhood orchid Pterostylis brumalis. NZ J Bot, 1-20.

This research was undertaken while Emma Bodley was an MSc student at the Centre for Biodiversity & Biosecurity, School of Biological Sciences, University of Auckland. She successfully completed her study and is now a Botanical Records and Conservation Specialist at Auckland Botanic Gardens. She was supervised by Anne Gaskett and Jacqueline Beggs.