15 December 2023 Redback romance to become even more tragic for spider pest

His desire is so strong he somersaults onto the fangs of the much larger female, offering himself up to be digested to ensure a successful coupling.

Lincoln spider expert, Dr Cor Vink, is part of a collaborative project looking to utilise that arachnid ardour against the Australian pest to save native endangered beetles.

Dr Cor Vink on the hunt for beetles and spiders in the Lewis Pass area. Photo: John Marris.

Dr Vink is part of the Plant and Food Research led three-year project, in collaboration with Ngāi Tahu and DOC, “Developing a pheromone tool for the eradication of Australian redback spiders”, which was granted $999,999 by the Endeavour Fund in 2023.

The venomous redback poses a threat to native fauna as well as humans. Any possible biological control would also harm the closely related native katipō spiders, so the team will attempt to recreate the pheromones, in a world first for pest management use, which attract the male to the female’s web, to be able to selectively target it.

“I’ve been interested in redbacks since 2008 when I was working on the katipo spider and found evidence that they had interbred in the wild with redback spiders. I did some further research and published a paper modelling their potential distribution in New Zealand," Dr Vink said.

Redback spider: Photo MPI

“Put simply, redbacks can establish anywhere with a suitable climate for vineyards as they need long, warm summers and dry conditions, but they can tolerate cold winters."

The paper predicted redbacks could establish in the Cromwell chafer reserve in Otago, the only place the endangered Cromwell chafer beetle is found.

“Sure enough, they turned up there two years later and were eating hundreds of Cromwell chafers.”

“It had been known for many years that male redbacks commit suicide when mating and a 2004 paper showed that males used airborne pheromones to locate females,” Dr Vink said.

“I figured that because males can only mate once, we might be able to limit their population by luring redback males with the pheromone and killing them (in a trap).”

He did preliminary work to try and identify the pheromone and showed that males could be attracted to it in a lab setting. However, progressing the research further would require the skills of an experienced pheromone chemist.

“Fortunately, I met Dr Andrew Twidle at Plant & Food Research a couple of years ago. Andy is a chemist who specialises in identifying moth pheromones and was sure that he could identify redback pheromones.”

Dr Twidle will lead the project and do the essential identification of the pheromones.

“My role on the team is as the spider expert; I’ll be advising on how to find redbacks, how to look after them and informing the team on the details of their biology," Dr Vink said.

Plant & Food Research’s Tom and Nicola Sullivan will do the technical work of catching and keeping redbacks, and designing and building traps.

Dr Tara Murray from the Department of Conservation is on the team to advise on the Cromwell chafer and the research will be done in consultation with Ngāi Tahu, with Meikura Arahanga on the team as cultural leader.

The first year of the project will be spent establishing a captive colony of redbacks and identifying their pheromones. In the second year, they will test the attractiveness of the pheromone in the lab, and design and test traps.

“By the third year, we’ll test the traps down in Central Otago,” Dr Vink said.

“Ultimately, we aim to have a pheromone lure and kill system that can be used to protect the Cromwell chafer, the Alexandra chafer and other threatened invertebrate taonga in Central Otago.”

The research will save precious taonga from extinction, increase science capability in Aotearoa-NZ and provide a new control technology to support future invasive spider eradications here and overseas.