Bt Research 2024, Vol.15, No.1, 65-75 http://microbescipublisher.com/index.php/bt 69 5.3 Resistance management strategies Resistance management is crucial for maintaining the long-term efficacy of Bt biopesticides. Strategies to manage resistance include the use of refuges, crop rotation, and the development of pyramided Bt crops that express multiple Bt toxins. Refuges, areas where non-Bt crops are planted, help maintain a population of susceptible pests that can dilute the resistance genes in the pest population. Crop rotation disrupts pest life cycles and reduces the selection pressure for resistance. Pyramided Bt crops, which produce multiple Bt toxins, are designed to delay resistance by targeting pests with different modes of action (Glaser and Matten,, 2003; Raymond et al., 2007). Additionally, integrating Bt with other biotechnological approaches, such as RNA interference (RNAi), can provide new avenues for resistance management (Zhu et al., 2016; Kang et al., 2021). Table 2 Average time (years) to corn rootworm resistance or extinction simulating a hypothetical non-high dose Bt pyramid with a 5% refuge and additional management tactics (Adopted from Martinez and Caprio, 2016) Strategy Block RIB Mean SEM Sample size Mean SEM Sample size Bt+refuge 21 7b 0.354 100 222b 0.262 100 Bt+refuge+SAI 21 7b 0.301 100 217b 0.265 100 20% increased refuge 25.5c 0.327 100 28.5c 0.361 100 Crop rotation 5.0a 0.025 100 5.1a 0.022 100 6 Economic and Social Considerations 6.1 Cost-benefit analysis The economic viability of Bt biopesticides is a critical factor influencing their adoption. Studies have shown that Bt crops, such as Bt cotton and Bt maize, can lead to significant economic benefits for farmers. For instance, Bt cotton adoption in China resulted in savings of approximately 8.46 billion US dollars on pesticide use over a 15-year period, with additional benefits from increased yields and reduced labor costs (Qiao and Huang, 2018). Similarly, a meta-analysis of GM crops, including Bt varieties, indicated that these crops generally lead to higher economic performance due to yield increases and reductions in pesticide application costs, despite higher seed costs (Finger et al., 2011). However, the economic benefits can vary significantly between regions, influenced by factors such as pest pressure and pest management practices (Finger et al., 2011). 6.2 Market demand and adoption The market demand for Bt biopesticides is influenced by several factors, including the cost of production, regulatory frameworks, and farmer awareness. The high production costs of Bt biopesticides, primarily due to expensive synthetic media and formulation processes, pose a challenge to their widespread adoption (Brar et al., 2006). However, alternative production methods using local media, such as vegetable waste, have shown promise in reducing costs while maintaining efficacy (Pan et al., 2021). The adoption of Bt crops has been substantial in countries like India and China, where Bt cotton has generated significant welfare gains for farmers (Qaim et al., 2008). Nonetheless, the market structure and regulatory environment play crucial roles in technology access and benefit distribution, affecting the overall adoption rates (Qaim et al., 2008). 6.3 Socioeconomic impacts The socioeconomic impacts of Bt biopesticides extend beyond direct economic benefits to include health and environmental considerations. The reduction in pesticide use associated with Bt crop adoption has led to improved health outcomes for farmers and reduced environmental pollution (Fletcher et al., 2020). However, there are also concerns about the potential impacts on non-target organisms and biodiversity, which necessitate careful risk assessment and management (Kaur, 2012; Manachini et al., 2013). Additionally, the deviation between farmers' willingness and actual behavior in adopting biopesticides highlights the importance of education and market structure in promoting sustainable practices (Guo et al., 2021). Addressing these socioeconomic factors is essential for the long-term sustainability and acceptance of Bt biopesticides.
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