Vive la resistance

Keeping pests and pathogens under control is fundamental for our ability to grow our food. Pesticides and antimicrobials can help but they can also leave farmers vulnerable if either fail to curb attacks on their crops. Over the last two decades a different option has transformed agriculture in several countries.

Genetically modified crops called Bt crops, after the common soil bacterium (Bacillus thuringiensis) that provided the genes incorporated in such crops, produce proteins that are toxic to insects but have little or no impact on other organisms. These crops have proved to be an efficient protection for farmers who produce crops like corn, cotton and soybeans. The use of Bt crops is now widespread, covering an area approximately the size of Ethiopia, but several pests are becoming resistant.

How to deal with this?

In a study recently published in the journal Ambio, centre researcher Peter Søgaard Jørgensen, along with colleagues from the US, Australia, India, Canada and Brazil, have analysed resistance management governance in Australia, Brazil, India and the US. Common to these countries is that Bt crops play an important role in agriculture. The objective of the study was to identify policies and strategies that can help sustain efficacy of Bt crops.

Ultimately, the study finds that a more joint effort and shared understanding among government regulators, technology providers and farmers can improve sustainability of Bt crops.

Link to publication

The role of farmers, companies, government offices

The prevalent strategy to manage Bt resistance in pests is the “refuge strategy”, in which non-Bt crops are planted to ‘distract’ some of the insects from going straight to the Bt crops. This also means that insects that survive on Bt crops have a higher chance of mating with individuals from the refuge that are not resistant to Bt toxins, which slows the evolution of resistance. But planting refuges may reduce yields, which diminishes incentives for farmers to use the refuge strategy.

“Individual growers directly bear the near-term economic costs of refuge adoption but only derive longer-term benefits of refuges through preservation of Bt effectiveness,” says co-author Peter Søgaard Jørgensen.

Then there is the role of technology providers that help preserve effectiveness of the Bt crops. This role varies across countries, where technology providers can be directly (e.g., US) or indirectly (e.g., Australia) responsible for enforcing resistance management mandates, or voluntarily coordinate efforts (e.g., Brazil) to improve grower implementation of resistance management strategies. Their incentives are shaped by property rights and market structure.

The role of government also varies across countries. Australia, India and the USA formally mandate use of resistance management measures and reporting of pest resistance, whereas in Brazil resistance management is voluntary.

In Australia, the implementation has been successful, largely thanks to a close collaboration between several stakeholders and direct linkages between the group that appraises resistance risks and farmers, which seems to have facilitated adoption of resistance management measures by farmers.

In the US, poor compliance has led to resistance problems despite sophisticated governance systems. India has also suffered from low compliance, largely because the overwhelming number of growers hinders sufficient monitoring.

Carrots and sticks

Solutions to many of the challenges facing each country could be provided by adoption of context-dependant “carrots and sticks” approaches, according to Jørgensen and his colleagues. Carrots include factors such as discounts for farmers to invest in refuge seed or extended patent lives to successful biotech companies. Sticks include factors such as restricted access to Bt seeds in cases of noncompliance with refuge mandates, or rejected re-registration of a Bt seed if a company does not comply with certain expectations.

With greater use of genetically modified crops in more parts of the world, developing robust resistance programmes for Bt crops is a priority, the authors write.

This means four things: farmer must be more sensitive to the risks associated with growing pest resistance, monitoring of both compliance and increase in pest resistance must get better, and actions to curb such resistance must happen quicker and more effectively.

All this requires a more collaborative management, the authors conclude.