To Catch a Predator

Story by Hamish Howard

Faculty of Science, 2018

Introduction

The development of ground-breaking, highly effective, long-life synthetic lures by Michael Jackson, from Victoria University of Wellington, promises to significantly advance the prospect of completely eliminating New Zealand’s worst invasive predators.

Predator Free 2050

New Zealand’s indigenous biota evolved in isolation and in the absence of land mammals (with the exception of three native bat species) over a period of approximately eighty million years. Consequently, human settlement and the introduction of foreign species resulted in significant and wide-ranging ecological effects.

New Zealand’s Predator Free 2050 (PF2050) programme aims to completely eradicate five invasive mammalian predators (possums, ship rats, Norway rats, stoats, and ferrets) by 2050. These species, all of which were introduced after the arrival of Europeans in the eighteenth century, have wreaked ecological havoc in New Zealand, contributing to the extinction of countless native species and threatening many more with the same fate. In order to achieve what has been labelled by supporters as a ‘moonshot’ and by one critic as an ‘Andromeda-Galaxy-shot’ huge economic, scientific and social barriers must be overcome.

Efforts to control or eradicate rat species on New Zealand’s mainland have been largely ineffective to date. However, complete eradications have been achieved on a number of offshore islands—an achievement that was long thought impossible.

The use of lures (and baits) to attract target species is central to many predator control and monitoring technologies and will be of great importance in the advancement of conservation programmes such as PF2050. Ongoing research and development promise to dramatically improve lure performance and reduce costs.

Baits and Lures

The toolkit for those attempting to suppress, control or eradicate introduced mammals is both varied and growing but the vast majority of these tools fall into two categories—poisons and traps. Target species are usually either baited into consuming poison or lured into interacting with a trap.

Typically, the longer a bait or lure can remain attractive to a target species the better.

Although longevity is often not a big issue in baits, as poisons will often biodegrade (by design) over short time periods, it is of great consequence in lures. Food-based lures (common spreads such as Pic’s Peanut Butter or Nutella) have been established as the most effective rat lures but their attractiveness declines rapidly over time and they are prone to mould and consumption by off-target species such as ants. Consequently, to maintain adequate performance, lures must be replenished on a regular basis.

To date, formulating long-life food-based lures has proven to be a zero-sum game. Either effective or long-lasting, increasing one of these traits will often come at the expense of the other. Synthetic lures have long been posited as a solution to the performance and cost issues of food-based lures but the development of such lures has itself been problematic.

Michael Jackson

In hindsight, it isn’t surprising that a Google search for “Michael Jackson”, using the keywords “predator control”, didn’t yield the results that I was looking for. Michael Jackson is a PhD student in Ecology and Biodiversity at Victoria University of Wellington, under the supervision of Associate Professor Wayne Linklater.

In 2017, a project led by Jackson was awarded $360,000 from the New Zealand Department of Conservation’s Tools to Market fund. The intention of this fund is to develop promising predator control science into operational tools that can then be used to assist in the PF2050 programme. Jackson’s project, informed by his thesis “Olfactory communication in rats (Rattus spp.) and Possums (Trichosurus vulpecula) and its implications to the development of semiochemical lures”, aims to develop highly effective long-life synthetic lures targeting rat species.

Michael Jackson's Research

Michael Jackson’s research involved extensive field testing and chemical analysis via a process known as Gas Chromatography and Mass Spectrometry (GC-MS). He first tested a range of different food items, commonly known or suggested as attractive to rats. He then identified Volatile Organic Compounds (VOCs) in these items and associated them with the behavioural responses he obtained from the original food products, identifying five compounds that were as attractive to rats as peanut butter. These compounds were then individually tested to determine the most effective concentration of each before being tested in combinations to identify any synergistic effects. VOCs are organic chemicals that evaporate (or sublimate) at ordinary room temperature, making them smelly. GC-MS is carried out using a fancy scientific machine and identifies all the specific substances that make up a given test sample.

Michael Jackson is now developing four new lures for commercial release, two of which contain just a single compound and two of which contain multiple compounds. These four lures will be produced both in reservoir (liquid) form and emulsion (solid) form. He is confident that these lures will perform at a level of equivalent or greater attraction than that of the best food-based lures on the market. Furthermore, a custom vial, containing only a few millilitres of lure, will be sufficient to operate at maximum potency for up to six months. If successful, his work could prove to be a technological breakthrough of great importance to conservation and pest control, both in New Zealand and around the world.

The Pest

  • <p>British Pest Control Association. https://www.flickr.com/photos/95230066@N07/29517958390</p>

Where this research originates

Victoria University of Wellington , Kelburn, Wellington 6012, New Zealand