New Zealand Journal of Ecology (2019) 43(3): 3385

Investigation of tutin, a naturally-occurring plant toxin, as a novel, culturally acceptable rodenticide in New Zealand

Research Article
Shaun C. Ogilvie 1*
Shona Sam 2
Arijana Barun 3
Cheri Van Schravendijk-Goodman 4
James Doherty 5
James Waiwai 6
Craig A. Pauling 7
Andrew I. Selwood 1
James G. Ross 3
Jennifer C. Bothwell 3
Elaine C. Murphy 3,8
Charles T. Eason 1,3
  1. Cawthron Institute, 98 Halifax St, Nelson, New Zealand
  2. DEI, NZDF, Burnham Military Camp, 1 Powles Road, Burnham, New Zealand
  3. Department of Pest-management and Conservation, Lincoln University, Lincoln, New Zealand
  4. Swamp Frog Environmental and Tree Consultants Ltd, Taupiri, New Zealand
  5. Tūhoe Tuawhenua Trust, Box 4, Murupara, New Zealand
  6. Lake Waikaremoana Hapu Restoration Trust, c/- Kuhapa Twin Lakes Store, Tuai, New Zealand
  7. Boffa Miskell Ltd, PO Box 110, Christchurch, New Zealand
  8. Department of Conservation, Christchurch, New Zealand
*  Corresponding author

He nui nga mātauranga a te Māori (Ngai Tūhoe) e pā ana ki nga momo hua tāokeoke (Toxins) e taea ana te whakarite hei rauemi tāwai i ngā riha kīrearea, pērā anō ki nga whiu takarangi o te tāoke 1080. I whakamātauhia e matou i nga ira tāoke o roto o te hua Tutu, ki rō taiwhanga pūtaiao. Mā te wero atu ki tētahi kiore (Norway Rat) i hua mai ngā mohiotanga o te nui me te momo o ngā tāokeoke kei roto i tēnei miro Māori, me te āhua o tēnei tāoke kia mau-rohā tonu tōna tuku whakahemo (Humaneness). Kei tua o te 55 mg kg−1 neke atu, te ine i tūtuki pai ai nga tāhawahawatanga o te miro Tutu, ā, e mau-roha tonu ana te kōhurutanga o te riha. Ko te whakatau kia kawea atu tēnei kaupapa ki nga ahurewa rangahau e taea ai te waihanga i tētahi mōunu tāokeoke, kia whakamātauria ki rō ngāhere. Hei tāpiritanga ki tēnei, he roa rawa te wā e pakari ai te whanaketanga mai o tētahi tākoe e rerekē ana ki te 1080, anō nei, mā ngā kawenga o te mātauranga Māori ki tēnei take e whanake tika ai te kaupapa nei.

New Zealand has many introduced mammalian species that are managed as pests of conservation and/or economic importance, including four rodent species. Vertebrate pesticides are the most important rodent management tool, largely dominated by anticoagulants such as brodifacoum, and by the metabolic disruptor, Compound 1080. There has been considerable opposition to these pesticides, primarily based on concerns about environmental persistence and non-target effects; Maori have been particularly vocal in opposition. Maori have place-based knowledge about naturally-occurring plant toxins that could be used as culturally-acceptable alternatives to existing rodenticides. In the context of the research presented here, the term ‘culturally-acceptable’ refers to new pest control options that have been co-designed with Matauranga Maori experts that inherently include Maori ways of thinking, being, and acting. Tuhoe researchers in our study wanted to pursue the most promising natural toxic compound found in native plants as a suitable alternative to current vertebrate pesticides. Therefore, we undertook an oral gavage trial to assess the toxicity of tutin, the toxin active in tutu (Coriaria arborea), to the Norway rat, (Rattus norvegicus). Tutin was toxic to this species at a dose of 55 mg kg−1, with a quick, humane death compared to other existing rodenticides. At a dose rate of 55 mg kg−1, all animals of both sexes died within an hour, and once neurological poisoning symptoms commenced these animals were unconscious within 5–10 minutes. We conclude it is warranted to take the next logical research step, which is to prove whether this dose rate would be technically attainable in the field. Although for now New Zealand remains reliant on 1080 and anti-coagulants for mammalian pest control, efforts should continue to develop more targeted toxins and delivery systems. We recommend incorporating Matauranga Maori to identify alternative control tools that could lead to more culturally acceptable pest control.