A brushtail possum in Mount Aspiring National Park. Could a toxin be developed that only targets opossums?
Perhaps the most promising alternatives to 1080 are toxins that target individual species such as rats without poisoning other animals.
These “species-selective” toxins are said to be based on a thorough understanding of pest genomes but not involve any genetic engineering, says a comprehensive new review of 1080 alternatives.
In theory, such a toxin could stop the hearts of opossums, say, but would have no effect on humans, birds, dogs, cows, sheep, or other species.
For example, a toxin called norbormide was developed in the 1960s that causes fatal constriction of blood vessels in some species of rats, but has only a temporary, asymptomatic effect in other animals, including others. rodents.
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Norbormide failed commercially because this selectivity made it less useful than other toxins. But this selectivity is a promising characteristic for researchers at Manaaki Whenua-Landcare Research and Invasive Pest Control Ltd.
“Recent development work … has dramatically improved its effectiveness, so that it is now at a level considered commercially viable,” reports Dr Bruce Warburton of Landcare and nine other researchers at the journal.
Department of Conservation
This provided video describes DOC’s efforts to measure the long-term effects of 1080 in New Zealand. He claims the number of birds has doubled in a valley on the west coast. (Video first published in January 2019)
Norbormide is not the only candidate, but if the approach is feasible, then researchers could develop individual toxins specific to possums, mustelids, mice, etc.
While these toxins can work in the laboratory, applying them on the scale needed to protect New Zealand’s birds and forests will require time and costly work with no promise of success.
As alternatives to 1080, species selective toxins should be humane, leave little or no toxic residue, and be cost effective. It does not help that New Zealand is almost alone in this fight and that the “market for [toxins] specific to New Zealand… is tiny internationally ”.
New Zealand scientists are interested in alternatives because of the discomfort associated with using 1080, especially when it is applied by air over large areas to target pests. There is sometimes “strong and often vehement opposition” to 1080, they note.
Warburton and colleagues support the continued use of 1080 aerial bait. It is “currently considered by far the most affordable approach to addressing major threats to conservation and agricultural production … posed by small mammals. harmful at the landscape scale ”.
But they acknowledge the opposition to 1080 and go through all the alternatives in a 43-page peer-reviewed article in the New Zealand Journal of Zoology.
It’s far too long and detailed to summarize here, but notes that the alternatives to 1080 could themselves become targets for the opposition.
1080 hunting, trapping and hand seeding are effective at small accessible sites, but not nationally.
Other promising alternatives involve genetic technologies. They could, in theory, make sure that no female was born, for example. No animals would be killed and the pest population would disappear over time.
But “they would undoubtedly be subject to significant scientific, regulatory and public scrutiny as part of New Zealand’s current approval process which governs the development and release of genetically modified organisms.”
The authors are clear, however, that stopping the use of the 1080 antenna would be folly.
“Clearly, if the 1080 air poisoning were stopped without an equally effective alternative, many of the conservation gains of the type reported by DOC and [scientists] would be quickly lost as opossum and predator numbers recover, much like the rapid increase in bovine tuberculosis infection in the 1980s, when opossum control was prematurely reduced, ”write they.