Bt Research 2024, Vol.15, No.1, 30-41 http://microbescipublisher.com/index.php/bt 34 Bt cotton seeds effectively delayed the development of resistance. This figure emphasizes the importance of appropriate refuge strategies in managing resistance. 4.2 Strategies for resistance management To mitigate the risk of resistance development, several strategies have been proposed and implemented. One of the primary strategies involves the use of refuges, which are areas planted with non-Bt crops to maintain a population of susceptible pests. This approach helps to delay resistance by promoting the survival of pests that are not exposed to Bt toxins, thereby reducing the selection pressure for resistant individuals (Carrière et al., 2016). Another effective strategy is the deployment of pyramided Bt crops, which produce multiple Bt toxins targeting the same pest. This approach has been shown to delay resistance more effectively than single-toxin crops, although issues such as cross-resistance and antagonism between toxins need to be carefully managed (Carrière et al., 2015). Additionally, integrating Bt crops with other pest management tactics, such as crop rotation and biological control, can further enhance the sustainability of Bt technology (Gassmann and Reisig, 2022). 4.3 Case studies of resistance management programs Some case studies have demonstrated successful implementations of resistance management programs. The study by Carrière et al. (2019) compared resistance management strategies in Australia, Brazil, India, and the United States. Effective governance relies on a shared understanding among regulators, growers, and stakeholders, supported by robust coordination and monitoring systems to ensure compliance and rapid remediation. Successful Bt resistance management projects combine regulatory guidelines with collaborative efforts from all parties involved (Figure 3). Effective governance requires monitoring growers' compliance with resistance management requirements and promptly implementing remediation measures. In Australia, a proactive resistance management program for Bt cotton targeting Helicoverpa species has been in place for over 20 years. This program includes rigorous monitoring of resistance allele frequencies and strong stakeholder support, with results showing no significant changes in resistance allele frequencies in field populations (Knight et al., 2021). In the United States, the use of Bt crops has led to regional suppression of pest populations and, in some cases, even pest eradication. However, instances of resistance evolution have also been recorded, emphasizing the necessity for ongoing monitoring and adaptive management (Gassmann and Reisig, 2022). Figure 3 Overview of the Institutional Analysis and Development framework for governance of Bt crops (Adopted from Carrière et al, 2019)
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