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Could daisy drive help make New Zealand predator-free?

Only if New Zealand communities help guide development of the technology.

Published onOct 03, 2017
Could daisy drive help make New Zealand predator-free?

To protect its taonga (treasured natural resources) and economy from introduced predators, New Zealand has committed to eliminating invasive rats, stoats, and possums by 2050. Because current control measures won’t be enough for rats, which are particularly devastating to birds, the plan relies on the development of new ecotechnologies.

Invasive rats devastate New Zealand's taonga. Left, a black rat preys on a nesting fantail. Right, a Norway rat with a dead blackbird.

Daisy drive systems can alter local populations by ensuring that desired traits are inherited for a limited number of generations. Unlike standard 'gene drives', daisy drives are inherently local because they depend on 'daisy elements' -  a form of genetic fuel that is used up as they spread. Using daisy drives to render the female offspring of two carriers infertile could reduce and possibly eliminate invasive populations without using poisons or causing any animal suffering.

Daisy drive systems, which rely on 'daisy elements' as a form of genetic fuel, can suppress and locally remove populations by ensuring that females born to two carrier organisms are infertile.

Community-guided research

Daisy drive hasn't yet been developed in rodents, but experiments are likely to begin soon. If the communities and citizens of New Zealand believe it might be of use to Aotearoa, then they should help guide the research from inception.

What does that mean?

There are several potential forms of daisy drive, each with different strengths and weaknesses. For example, rodents could be reliably removed by first altering populations and then eliminating them, or more quickly but less reliably by suppressing them directly. Basic daisy drive systems are likely to be most effective for direct suppression, while the harder-to-build 'daisy quorum' would be better for the slower, two-stage approach. Daisy quorum could also prevent international incidents by causing natural selection to swiftly eliminate any daisy drive systems carried by organisms that escape the islands.

In a daisy-chain drive system (top), each daisy element ensures that the next in the chain is inherited. But the one currently on the end doesn't enjoy this benefit, so it has a 50% chance of being lost in each generation until all elements are gone and the drive stops. This reliance on genetic fuel makes daisy-chain drive systems akin to a multi-stage booster rocket. Adding more elements to the daisy-chain is like adding more booster stages, increasing the power of the effect. In a daisyfield drive system, there are many daisy elements that all ensure that the desired change is inherited. Half are lost in each generation until the drive stops. The two versions may have different strengths and weaknesses.

Which version(s) of daisy drive should be developed for New Zealand, if any, and how should they be tested for safety and stability? When and where should field tests take place, and how should they be monitored? These questions are best answered with the help of local citizens.

Moral and practical benefits

Inviting people who might be affected by a technology to help guide its development is important because any other approach would deny them a voice in decisions that will affect them. More, asking citizens to share their suggestions, concerns, and criticisms can improve real-world outcomes, especially for ecotechnologies. Simply put, people with a deep connection to an ecosystem often have an intuitive sense of the way the environment is likely to respond. If they share their wisdom, the new technology can be developed in a way that is tailored to respect the unique needs of local ecosystems.

It might seem strange to invite others to prove you wrong, but that’s exactly how science works. There’s no reason to limit the invitation to professionals; anyone can have a useful insight. Since scientists should hold themselves morally responsible for all the consequences of their research, the chance to learn that a project is unwise and halt it in time is well worth the humiliation.

Reasons for skepticism and points in favor

There’s a real chance that current predictions regarding the usefulness of daisy drive will be proven wrong. That’s because the technology is still mostly theoretical: only very basic versions have been demonstrated in a handful of species, and none of those is a rodent. It's possible that daisy drives won't work as well as expected, or that unanticipated problems will require many additional years of optimization to correct. It's also far from clear how to adequately test safety and stability in the laboratory.

More generally, many people are wary of altering complex ecosystems because it's hard to predict the effects. Others are particularly concerned by genetic engineering, not least because communities weren't consulted during the development of engineered crops. Given these uncertainties and existing tensions, as well as the irreplaceable nature of the taonga, it is wise to be cautious.

On the other hand, New Zealand has already committed to removing pests, which would certainly change the local ecosystem. The question is whether daisy drive should be one of them. There is no getting around the fact that it involves genome engineering, but if it succeeds in removing rats, there wouldn't be any edited genes left. Similarly, an open and community-responsive development approach would be the polar opposite of the traditional closed-door strategy used for engineered crops. Most importantly, helping to guide technology development doesn’t imply a commitment to use the technology. There’s more than enough time to say no.


'Responsive science' may sound like a good idea, but we don't know the best way for communities to guide research. The Eliminate Dengue and Target Malaria projects have engaged local communities and invited feedback on safety testing of their engineered mosquitoes. But few projects have invited communities and their representatives to guide technology development from the very beginning. One noteworthy example is Mice Against Ticks, which seeks to prevent tick-borne diseases by engineering the local mice that normally infect ticks in eastern North America.

The Mice Against Ticks project is directed by Steering Committees appointed by the Boards of Health of the island communities of Nantucket and Martha's Vineyard. Each Steering Committee includes local citizens, doctors, researchers, and a vocal skeptic of the project, whose job is to share the concerns and insights of people who might not otherwise speak up. Scientists at the Massachusetts Institute of Technology and neighboring universities are the project’s hands, laying out the technical possibilities and working to realize them, or not, as directed by the Steering Committees. Citizens can share their insights with Steering Committee members, or they can directly speak with the scientists during one of the frequent town hall meetings. Around 2024 or later, island citizens will vote on whether to release up to a hundred thousand mice, engineered according to their specifications, onto each island.

Do any lessons of Mice Against Ticks apply to daisy drive and New Zealand? The obvious problem is scale: Nantucket and Martha's Vineyard harbor less than fifty thousand people between them; Aotearoa is a hundred times bigger.

A possible solution involves the many organizations devoted to the shared goal of making the country Predator-Free. Since daisy drive would be part of this broader initiative, its development could be governed by one or more of these groups. On the other hand, it's not obvious which group would lead the effort, so it may be wise to set up an alternative form of governance. Given the ecological focus of the project and the importance of using matauranga - traditional Maori knowledge - to help guide environmental decision-making, the best course of action would involve leadership and project co-governance by Maori.

Source - Predator-Free New Zealand.

Key questions for New Zealand citizens and communities

Is daisy drive a technology that could benefit Aotearoa?

What would success look like?

How might things go poorly?

How should these community concerns and criticisms be shared with the scientists working on the technology at MIT? Through the existing Predator-Free New Zealand project? Using an online discussion forum? Some other way?

How should the scientists respond?

Ultimately, the decision of whether to guide the development daisy drive is up to the people and government of New Zealand. Suggestions, concerns, criticisms, and responses to the above questions are more than welcome.

Kevin Esvlet's talk on invasive rodents at the University of Otago - 17 September 2017

Kevin M. Esvelt, a professor at the MIT Media Lab, is an inventor of daisy drive technology.

Jamie McAulay:

Great piece and some very interesting points. The idea receives a fair amount of press here in New Zealand and it’s this type of discussion that really needs to begin happening. Very interested in the sorts of questions you are asking here- just how to have ‘a community discussion’ with millions of people from wide and varied communities. Would be intrerested to hear peoples thoughts.

Joel Zwartz:

Finally got round to watching the whole of Kevin Esvlet’s lecture, including the questions. I was waiting for someone to ask (looking at you, Jamie) : OK, so the tech for mice will be available relatively soon, then norway rats and ship rats, BUT if they were released in that order, what would be the ecological effects on NZ birds ? Stoats, deprived of rats and mice to eat, would mostly feed on birds instead. (I’m guessing the answer to this depends on where you are).

And, how suitable is this technology for use on stoats? They do a lot of incest, I’m told, so could an unaffected family of stoats repopulate NZ with inbred stoats?

Avery Normandin:

This is another test

Avery Normandin:

That’s a great idea!