PlantwisePlus Blog

Pink bollworm larvae, photo by Peggy Greb, USDA Agricultural
Research Service,

It was love at first sight for many pink bollworms this year, but as their eyes met across the cotton field all was not as it seemed…

Oxitec (a company based not far from the Plantwise Knowledge Bank team), have managed to genetically engineer a strain of pink bollworm (Pectinophora gossypiella) which greatly advances the already used sterile insect technique (SIT). The new strain (affectionately known as Pink Bollworm OX3402) has been genetically engineered to include bisex RIDL technology, which means that they have a RIDL gene that effectively makes them sterile (offspring cannot survive without additional dietary supplements). OX3402 also has Oxitec’s heritable fluorescent marker technology (DsRed), which allows populations of released strains to be monitored more accurately.

The idea behind both SIT and RIDL is that by sterile individuals mating with fertile individuals the number of viable progeny is reduced, and after a high enough number of releases the pest population crashes. In SIT sterilisation is achieved by carefully measured doses of radiation, while in RIDL it is part of the genetic make-up, and this is what gives RIDL technology the edge over SIT. The ‘in-built’ sterility gives greater biosecurity in the case of accidental release, and there isn’t the cost or risk associated with the radiation centres needed, so the method can be used in much smaller projects. By using RIDL rather than SIT, the males’ fitness is also less compromised, so they are more able to compete successfully for wild females, and thereby increase the efficiency of such pest control.

RIDL technology is not only environmentally friendly on its own, but could become an important part of integrated pest management systems, too: “Sustainability is key here: blasting pests with an insecticide might work in the short-term, but a more integrated approach massively reduces the risk of control breaking down [e.g. by insecticide resistance evolving] – we see RIDL as a potential cornerstone of sustainable control for some of the world’s most significant food pest species” Dr. Neil Morrison from Oxitec told Plantwise. “RIDL’s chemical-free and species-specific mode of action will provide effective control with minimum impact on the environment.”

So how will this help farmers in developing countries, who often don’t have access to the latest pest control techniques, and where pesticides can provide an easy, fast and sometimes cheaper solution? Oxitec is keen to make their products widely available, and their plans for the future aren’t just to develop new and more advanced products; they also plan to work with partners around the world to ensure that RIDL is an option for as many farmers as possible.

The innovative work done so far could provide farmers with a very powerful weapon in the battle against crop pests and diseases, but the story is still far from complete. Further trials have been and still are being conducted, so watch this space for future developments!

For more details on Oxitec’s work click on the link above, or to see an article on Oxitec’s work in the New Scientist, click here.

Many thanks go to Dr. Neil Morrison and Oxitec for their co-operation in providing further information about this and other pest control techniques.

Other sources:

Simmons, G. S., et al. (2011) Field performance of a genetically engineered strain of pink bollworm, PLoS ONE  6(9), doi:10.1371/journal.pone.0024110


  1. John Wightman on 22nd December 2011 at 12:20 AM

    Really good – I investigated the possibility of inducing sterlity in a swag of UK horticultural pests that resurged after DDT was with withdrawn in the 1960s. I rejected the concept for a number of reasons. BUT what does RIDL stand for???

  2. Claire Shepherd on 22nd December 2011 at 10:33 AM

    Hi John, RIDL stands for ‘Release of Insects carrying a Dominant Lethal’. Hope that helps!

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