Release of sterilised moths avoids the need for refuges in cotton growing

 Success in integrated pest management of pink boll worm in Arizona provides encouraging news for both the environment and for cotton growers. A two-pronged strategy involving insect protected cotton and biological control with wide scale release of sterile moths virtually eliminates resistance to the genetically inbuilt cotton insect protection system in pink boll worm pests.

Summary of the original scientific publication:
Suppressing resistance to Bt cotton with sterile insect releases

Bruce E Tabashnik, Mark S Sisterson , Peter C Ellsworth, Timothy J Dennehy, Larry Antilla, Leighton Liesner, Mike Whitlow, Robert T Staten, Jeffrey A Fabrick, Gopalan C Unnithan, Alex J Yelich, Christa Ellers-Kirk, Virginia S Harpold, Xianchun Li & Yves Carrière

Abstract

Genetically engineered crops that produce insecticidal toxins from Bacillus thuringiensis (Bt) are grown widely for pest control. However, insect adaptation can reduce the toxins’ efficacy. The predominant strategy for delaying pest resistance to Bt crops requires refuges of non-Bt host plants to provide susceptible insects to mate with resistant insects. Variable farmer compliance is one of the limitations of this approach. Here we report the benefits of an alternative strategy where sterile insects are released to mate with resistant insects and refuges are scarce or absent. Computer simulations show that this approach works in principle against pests with recessive or dominant inheritance of resistance. During a large-scale, four-year field deployment of this strategy in Arizona, resistance of pink bollworm (Pectinophora gossypiella) to Bt cotton did not increase. A multitactic eradication program that included the release of sterile moths reduced pink bollworm abundance by >99%, while eliminating insecticide sprays against this key invasive pest.

Nature Biotechnology
Published online: 7 November 2010 | doi:10.1038/nbt.1704

David Tribe

Written by David Tribe

David Tribe’s research career in academia and industry has covered molecular genetics, biochemistry, microbial evolution and biotechnology. He has over 60 publications and patents. Dr. Tribe's recent activities focus on agricultural policy and food risk management. He teaches graduate programs in food science and risk management as a Senior Lecturer in the Department of Agriculture and Food Systems, University of Melbourne.

9 comments

  1. I also wonder, in the case of the economics on the farm, if the sterile moth strategy eliminates most of the bollworms, then wouldn’t the cost-benefit calculation favor planting a (larger?) refuge to save on seed costs? If it knocks out the population pretty hard, then it would seem that there are fewer moths around to pester the non-Bt cotton.

  2. What is the cost of sterile moths relative to the cost of planting a refuge?

    Very good question – seems at present the USDA breeds the strain of moth used and then irradiates them to sterilize – given the vast numbers of moths processed at a time my initial guess is that the treatment can’t be that expensive on a per acre basis.

    I also wonder, in the case of the economics on the farm, if the sterile moth strategy eliminates most of the bollworms, then wouldn’t the cost-benefit calculation favor planting a (larger?) refuge to save on seed costs?

    The strategy still seems to hinge largely on the efficacy of Bt to knock the population down as hard as possible leaving only resistant (very few) moths to emerge & reproduce – you then swamp this population with steriles and prevent the gene from moving to the next generation – larger refuge would mean larger moth population in situ which would either mean you’d have to release more sterile moths, or you’d risk matings between resistant individuals and fertile moths maintaining the allele(s) in the population (at least by my reading – seems the strat would work best without any refuge at all – in terms of efficacy and using min number of sterile moths)

    Indeed – depending on cost of Bt cotton seed vs costs of sterile moths and their relative efficacy rates, perhaps sterile moths alone would be a suitable control strategy

    I’m guessing this would require a ridiculous number of steriles to ensure they were mating with every available female asap – the key here appears to be swamping the natural population with so many males that naturalxnatural crosses are statistically unlikely – this depends heavily on killing most of the worms.

    Do the sterile males, themselves, eat the cotton plants?

    Afaik only the worms eat the plants – the moths eat whatever it is that moths eat (McDonalds I guess)

  3. Oh one other thing…. Radioactive moths!!!!!
    Has Greenpeace been informed?
    Spiderman is cool.
    Pink bollworm man – not so much.

  4. Do the sterile males, themselves, eat the cotton plants?

    That was kind of dumb of me. Of course the sterile males don’t eat the cotton, and don’t father any caterpillars.

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