After Mosquitos, Moths Are the Next Target For Genetic Engineering

By Nathaniel Scharping | May 10, 2017 4:14 pm
Diamondback moths. (Credit: Oxitec)

Diamondback moths. (Credit: Oxitec)

Though genetically modified crops may steal the spotlight, similarly reprogrammed insects may have just as big an effect on the agricultural industry.

Biotechnology company Oxitec is moving forward with plans to develop genetically engineered diamondback moths in an attempt to reduce populations of the invasive crop pest. Their plan is to release males that will pass on a gene preventing female offspring from reaching maturity and reproducing, which they say will eventually eradicate the moths in North America. Tests have so far been positive, although there are still worries about the prospect of releasing genetically modified organisms into the wild.

Pervasive Pest

Currently, pesticides are used to control the moths, which are responsible for an estimated $5 billion worth of damage every year in the U.S. An invasive species, the diamondback moth originated in Europe, but has proved difficult to control since appearing the U.S. due to short gestation times and the large numbers of eggs females lay at once. Oxitec says that their technique is preferable to pesticides, as the moths have proven capable of evolving resistance to the compounds in the past, and most carry some risk to the environment and human health.

Oxitec cites a USDA analysis that found no risk of significant impact in an earlier test of the GM moths as evidence that their technique is safe, but the prospect of GM insects raises fears that the moths may proliferate beyond targeted areas and cause impacts on the broader ecology. Similar techniques have been applied before, reaching as far back as the 1950s when sterile screwworm flies were released in Florida, effectively eliminating the parasitic species there. Impotent mosquitos, also manufactured by Oxitec, have been used to combat Zika in South America, and plans to implement the same procedure in Florida are underway.

Technique Has Precedent

The successful screwworm campaign relied on blasts of radiation to sterilize the males. Oxitec’s technique uses gene editing engineering to implant males with modified DNA that ensures female caterpillars don’t survive to adulthood. In the case of the moths, males need not be targeted because it is only the female caterpillars who are responsible for damaging the crops.

They say that tests of the moths, including feeding them to various animals and releasing them in greenhouses, have revealed no ill effects as a result of the genetic modification. Along with the caterpillar-killing gene, the moths are also implanted with a gene that causes them to fluoresce red under UV light, the better to identify them in the wild.

Fluorescent_Gm_Moth

The FDA found no issues preventing the company from moving forward, but because the moths are an agricultural pest, the USDA must weigh in as well. Oxitec is currently waiting on USDA approval to conduct expanded tests at a site in New York in conjunction with Cornell University. They hope to release the moths in a contained cabbage field to see how effective their modifications are.

Most opposition to genetically modified insects is based on the prospect of altered organisms spreading beyond the areas they are released. In the case of the diamondback moth, Oxitec says that the nature of the modification, which precludes breeding, should serve to limit the spread of the GM moths, and pesticides and freezing winter conditions should take care of the rest. While there is a precedent for this kind of technique in screwworms, those insects were uniquely suited to sterilization-based population control because of their life-cycles. Moths may present additional challenges.

Kevin Esvelt, a professor at MIT and leader of the Sculpting Evolution Lab agrees that the general concept is sound: “The whole point is to harm the next generation of organisms. And since they carry the relevant genetic construct, it’s necessarily going to decrease,” he says. “It will not persist in the environment over time as long as the genetic construct is doing what it’s supposed to do.”

Not A Gene Drive

This marks a crucial difference from a gene drive, a technique often associated with genetically modifying populations. The hallmark of a gene drive is tweaking genes to increase the chances that a particular trait will be passed on to offspring. The odds are normally 50/50, but a gene drive can tilt them in favor of a particular set of genes, causing a trait to spread through a population. This is helpful when a trait is detrimental to an organisms survival and would normally be weeded out by natural selection. Gene drives haven’t yet been applied in the wild, though, and likely won’t be for many years.

Oxitec’s moths possess no such scale-tipping modifications that could cause the modified genes to spread across the globe, they merely pass on genetic material in the normal way. Part of this genetic material, however, has been changed to ensure that female caterpillars with the gene don’t survive.

“From a technical perspective it’s a perfectly sound approach, it probably offers fewer risks than current approaches using pesticides. In general I am a fan of using biology to solve ecological problems as opposed to chemistry,” Esvelt says.

Still, he says that field trials are an important step in testing the efficacy and safety of any genetically modified organism. Along with careful tests, Esvelt advocates for more community involvement in the decision making process, as well attempts to reach out and communicate with critics. Although both the FDA and USDA have a period in place during which the public can comment, Esvelt says more communication should be done earlier.

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  • http://www.mazepath.com/uncleal/qz4.htm Uncle Al

    You only get one, but it’s a big one. Youtube v=stavnP7kcGU, v=34ClddoGLJ4. v=mkni0IqqYUM

  • OWilson

    Forget that finely balanced interdependent biosphere on our Blue Marble planet.

    Humans know better than Mother Nature.

    They will decide which of our amazing biodiversity will be allowed to live.

    Let me guess, the cute furry ones? :)

    • Charles Rader

      OWilson, We should be intelligent enough to recognize that all species have their place in nature. But we still compete with some other species, especially those that ravage our food supply.

      Right now, the diamondback moths are being controlled by spraying poisons. These poisons don’t affect only the diamondback moths. They hurt other insects that we don’t even mean to harm. When somebody comes up with a method of pest control which targets only the pest, that’s a GOOD thing for biodiversity.

      • OWilson

        When you are playing god, it’s always good to take a step back and make sure. How dire is the threat?

        They are poisoning starfish on the reefs by the thousands, as reported here, and producing abortions on Canada Geese in my parks (after inviting them in by creating wetland habitat).

        On a human level, who get’s to decide which species, Islamists, Christians, Jews, Gays, should be eliminated or genetically modified, lobotomized, or aborted is a heavy responsiblity.

        It’s a dirty job but they always have a line up of folks willing to do it!

        • http://www.mazepath.com/uncleal/qz4.htm Uncle Al

          Perhaps the only decent place on Earth not fouled by people is Chernobyl. Pre-fouled!

        • Charles Rader

          OW, first, let’s be clear. I am NOT playing God. I’m not a farmer. I don’t spray poisons. I don’t harm Canada geese. I don’t live anywhere near a reef and I don’t poison starfish.

          In fact, I have done a number of things that you would surely approve of, like producing sources of sustainable energy, keeping sewage from polluting an estuary, etc.

          The trouble with the “playing God” reprise is that it implies that we should leave everything alone. But we don’t leave everything alone. Before I built the solar array, our town was using electricity, but it came mostly from burning fossil fuels. Now it comes mostly from sunlight. Would you say I was playing God? I doubt it. Before I got the sewage treatment plant going, there was still sewage, but now it gets processed to be harmless. Would you call that playing God?

          Perhaps you think farmers should not do anything to protect their crops. OK, but they do. Unless you can get us all back to the hunter/gatherer stage, the choice is really about how to protect crops in the least environmentally disruptive way.

          When somebody proposes a new means of crop protection that might be less harmful, and wants to test and evaluate it, don’t say that he’s playing God.Hope instead that the idea works.

          • OWilson

            I love what you do and support it 100%.

            It’s just that life (flora, fauna) to me is different from a power generating source.

            I’m upset that since Roe vs Wade we have killed over 50 million babies, more than Hitler, Stalin and Pol Pot combined, and counting, but that’s politics, and to me not human progress.

            I’ve seen the same “certain” logic, over my lifetime, have so many unintentional consequences, that an “oops!, and a total reversal of policy (see Toronto’s Canada Geese progroms) is not enough to give me confidence in these policies.

            If you’ve ever seen laughing “environmentalists” chase and run down a mama polar bear and her cubs by a noisy helicopter, fire a sedating gun, staple a transmitter to her ear, leave her and her terrified cubs to hopefully recover, and go on to the “next!” you might see what I mean.

            YouTube has it!

          • Charles Rader

            OW, Regarding {life (flora, fauna) to me is different from a power generating source.} I think you are ignoring the fact that life is affected by many other things beyond straight out killing.

            I hope you can recognize that Roe vs Wade, although it has allowed many abortions, is not really a threat to nature.

            Let’s concentrate on the specific issue here. A method is being proposed which might be able to protect broccoli and cabbages from diamondback moths, who would otherwise be poisoned by chemicals. The chemicals also harm other species. Cornell’s scientists want to evaluate the proposed technology. If it works well and it reduces pesticide use, that’s great. If it doesn’t work well, we’ll have to try something else.

            If you think we should, without any further consideration, continue only current agricultural methods, do you understand that your decision causes needless death in the natural world?

            There’s a widespread attitude that anything genetically engineered is bad, no further consideration needed. But serious ecologists understand that it is necessary to consider each proposal on its own merits.

          • OWilson

            Silly me!

            I should have said that 60 million (aborted) murdered babies since Roe vs Wade, makes me as “uncomfortable” as that student wearing an American flag T-shirt on the Cornell campus!

            Might have some relevance to you progressives!

          • Charles Rader

            It’s really not clear to me why your views on abortion have any relevance to your views about agriculture. Can you really be associating the control of insect pests with the rights of human beings, unborn or not? And what has being progressive to do with farming? Take a look at one of those maps that shows US counties colored red and blue depending on whether they voted for Trump and Clinton. Do you think that the red counties are as worried as you seem to be about the rights of diamondback moths?

          • OWilson

            Of course not,.

            Out of sight, out of mind. :)

          • Charles Rader

            OW, either I don’t understand you at all, or you have gone 180 degrees from your initial post.

            Without bringing in any other issues, can you tell us whether you do or do not want the government to allow Cornell to do experiments which are intended to evaluate the use of GMO insects to reduce populations of diamondback moths?

          • OWilson

            I think that genetic engineering designed to exterminate a living natural species, should proceed cautiously, under strict and well debated government policy (sorry Uncle Al) that has the support of Congress.

            I have a natural aversion to genetic engineering of species, having survived WW2, and the new science that was going to free man from all disease and other impure genetic defects (to be determined as needed, by the brave new world).

          • Charles Rader

            OK, that’s a good answer.

            But you need a few facts.

            First, whatever you may have read elsewhere, this is NOT meant to exterminate a species. It is meant to keep its population low in a region where it is a serious pest. It would not work to exterminate the diamondback moth unless the sterile moths were released everywhere and at the same time. Don’t mix up the Oxitec approach with the gene-drive approach.

            Second, this is surely “proceeding cautiously”. The trait is designed to not establish itself. There have been a series of experiments within confined spaces, which have not shown any problems. There’s been government regulation all the way, and this particular test is meant to get more information, not to put the technique into commerce. Did you notice that the GMO moths also have another trait, red fluorescence. That’s so that the GMO insects can be found in a mixed population.

            I suspect that the Oxitec genetic engineers and the USDA regulators would welcome any intelligent suggestions about how to be as cautious as possible.

          • OWilson

            “Not meant” has no validity for me when you are talking about politicians who would happily and willfully do what the Founding Fathers warned the world about, namely, the weakness of the democratic systems that would allow a caropetbagging political party that would bribe the electorate, using it’s own treasury, to achieve and remain in power.

            They didn’t even stop when the Treasury was empty. They just kept on bribing with the free lunch until, not only was the Treasury empty, they had actually borrowed more money than could ever be paid back in their lifetimes.

            They just kicked it down the road to who knows who. They’d be long dead before the bills became due!

          • Charles Rader

            OW, you seem to have gone off the deep end. Nobody here was talking about politicians, but about agricultural scientists and methods of growing food. Not deficit spending, not gun control, not abortion, not conservatives or progressives, not press freedom. If that’s what you want to talk about, go and comment on a politics article.

            In your previous comment you said {I think that genetic engineering designed to exterminate a living natural species, should proceed cautiously, under strict and well debated government policy … }

            In my reply, I explained to you that the Oxitec technique was not meant to exterminate the diamondback moth, which was one of your reservations. I also gave some examples of ways that the evaluation was proceeding cautiously, which was another of your concerns. But you don’t seem to even be interested in this topic.

          • OWilson

            I was interested in your advocacy of a government sponsored genetic engineering program on a live species, that was “meant” (and you’ve said this at least 5 times in your last two posts) to improve methods of growing food.

            I merely pointed out in my original posts (you responded to me, remember?) that I have seen too many official programs affecting wildlife, that were “meant” to be warm and fuzzy and beneficial, but turned out later to have the opposite effect.

            I urged caution, rather than blind enthusiasm.

            I have been lectured likewise on how killing over 60 million babies since Roe vs Wade is beneficial to society, but I will be happy to remain in the minority who are “off the deep end” with the opposing opinion.

            Thanks for the comments, I’ll give you the last word (as long as you don’t ask leading questions that logically require an answer, or some ad hominem insult, which is not uncommon on these blogs) :)

          • Charles Rader

            Thanks for the “last word”. If we leave out the unrelated left-right politics, I think we are reasonably close to agreeing, but there’s still something I can’t figure out.

            In your mind is it OK to take steps to drastically reduce the population of pest species in a local area where that population is destroying an agricultural resource? If that is allowed, is it less allowed when accomplished by genetic engineering as opposed to, say, spraying poisons or sterilizing male insects by exposure to radiation or insect pheromones?

            The usual intelligent objections to genetic engineering in agriculture are not about extermination of a species. A more common concern is about introducing a new gene into the gene pool of a wild species, and surely the Oxitec scientists have been aware of this concern and designed their technique to make that virtually impossible.

            One more comment. You refer to this technique as “government sponsored”. There’s no reasonable sense in which this is government sponsored. Oxitec is a private company which wants to do some outdoor testing, with no reliance on government sponsorship. All it asks from the government is “Government, please do not forbid us from doing the testing”. Since you identify yourself as conservative I would expect you to want the government to do only the minimum regulation consistent with public safety.

          • OWilson

            I’m probably always going disappoint your “expectations” of me.

            After all I have been designated “deplorable” by your last Presidential Candidate who won the popular vote, and much, much worse here.

            I’m happy to wear that label proudly, considering the source.

            (Your own “gone off the deep end”, is a mere trifle! :)

            But I did my best to give you my own point of view and how it developed over my long and varied life lived in several countries of the world.

            But I’m done here!

            Peace!

          • Charles Rader

            Peace to you.

            By the way, you just said “your government” meaning “my government”. It sounds like you don’t consider it your government.

          • OWilson

            It’s simple.

            I’m Canadian! (When you guys sneeze, we catch a cold, 5 years later) :)

      • http://www.mazepath.com/uncleal/qz4.htm Uncle Al

        Insects molt. Given a juvenile hormone mimic, they molt to death. N,N’-dibenzoyl-tert-butylhydrazine does this, modestly, but hydrazine is hematopoietic toxic to mammals (Meryl Streep, apples, Alar/daminozide).

        I was in Canada to create a small, modular, non-hydrazine molecule re spruce budworm, gypsy moth, cockroaches, etc.. The deal: we pay for research reduction to practice (12 months over four summers). Canada then makes a few thousand combinatorial chemistry variations plus binding assay to optimize potency and species selectivity (about two weeks, commercial Canukistani pharma lab).

        Canada, “it can’t be done by one guy, but, OK.”
        Canada, “it is not potent enough to go forward.”
        Canada, “It is too expensive to commercialize.”
        Canada, “What the Hell! We’ll think about our end of the deal.” That was in 2007.

        Charles Rader – do you want to save the world from crop pests and cockroaches without harming people or bees? Go kiss Canada. I’m not telling.

  • Charles Rader

    “eventually eradicating the moths in North America.” ???

    I would like this experiment to go forward, but it’s silly to make the claim that it would eradicate the species. The screwworm analogy is flawed. Since the modified insects have no survival advantage over the wild type, they won’t spread by themselves into the wild population. They can eradicate a local population but wild type moths will then migrate into the area, or the occasional rare survivor can quickly repopulate the treated area.

    With Oxitec’s system, the GMO moths would be released repeatedly, not just once and done. If the GMO moths are released each season, the cost of the raising them is a part of the cost of growing the crop, just as is the cost of a conventional pesticide. But probably well worth it for the diamondback moth and absolutely worth it if the farmer uses fewer wide spectrum pesticides.

    • Brad Braun

      The naysayers don’t want to understand. They don’t want to know that the modified moth is self-limiting and can’t survive beyond a single generation when released. They’re fearful. Nothing trumps logic like fear. Sigh. The result: We’ll continue to ingest insecticide-laden food crops when a sound alternative to crop spraying exists. We’ll continue to accept the collateral damage to the environment when a sound alternative to crop spraying exists.

      If the current technology for controlling screw worms had face the same fear, it would be quashed too. Ignorance breeds fear and fear trumps logic every time.

      • Rich Lancaster

        Apparently fear didn’t stop humans from creating our current food supply that we routinely spray with poisons today, and then consume.

        The ignorant, fearful population are still trying to digest glyphosate, literally – so how about accepting that science, coupled with greed, has led us astray routinely in the past, and present. How about the greed slows down long enough to honestly bring people along for the ride with transparency and far less hubris?

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