Scientists extracted the active ingredient, tutin, using a purification process, and tested it on lab rats. The research found that a lethal dose killed rats faster and more humanely than many other existing pesticides.
In the study, a dose of 55 mg kg−1 killed rats within half an hour on average. In comparison previous research has shown it takes up to 10 hours on average for a lethal dose of 1080 to kill a rat, and up to 11 days on average for lethal dose of Diphacinone, an anticoagulant poison used by New Zealand councils for pest control.
The study also found the rats had a shorter period of consciousness before death when compared to poisons like 1080, brodaficoum and cholecalciferol.
Lead researcher Dr Shaun Ogilvie says tutin could well be an effective alternative to other rat poisons on the market.
“At this dose, tutin could be considered more humane than all other presently available rodenticides in New Zealand”, he says.
Dr Ogilvie says harnessing Māori knowledge, or Mātauranga Māori was key to the study, which found that some Māori have been particularly vocal in opposition to pesticides like brodifacoum and 1080.
“We had some discussions with kaumatua in Tuhoe country, they suggested in actual fact there's quite a few toxins already available in the forest”
“Māori have placed-based knowledge about naturally occurring plant toxins that would be considered more appropriate to use, because they evolved in this environment.”
The tutin was extracted from wild-sourced plant material. Technical manager of Cawthron Natural Compounds Andy Selwood says the study helped scientists to understand the chemistry of tutin.
“This may help us in the future if we need to prepare this on a larger scale”, he says.
“There's not going to be a silver bullet, or one solution to this problem, but I think the more tools we have available, the better we can start controlling these invasive species.”
Forest and Bird says we need to keep developing different pesticides, but in the meantime 1080 is “the best we’ve got”.
Forest and Bird’s Chief Conservation Advisor Kevin Hackwell says fluoroacetate, the toxic component of 1080 is also found naturally in many plants including in puha.
“So it is possible that a Mātauranga Māori approach could also have worked with fluoroacetate– 1080”.
Mr Hackwell says it’s likely that potential new pesticides “will complement, rather than replace, well-established and effective tools.”
The tutu plant can be toxic to other animals, including humans. Sheep and cattle have died after eating it, and in 2008, 22 people fell ill after eating tutin-contaminated honey.
Dr Ogilvie says it’s already known that tutu is dangerous to humans, so all the usual safety precautions should be taken with it.
The researchers say there’s still plenty of work to be done – they need more funding to test tutin in the field and on other pests such as possums. Testing also needs to be done to ensure there’s a minimal chance of secondary poisoning.
“It’s difficult to have a 1080 conversation without getting into some quite deep and emotional arguments, but from my point of view it’s about the research and coming up with different tools in the toolbox for managing pest animals in New Zealand,” Dr Ogilvie said.