Bt Research 2024, Vol.15, No.1, 65-75 http://microbescipublisher.com/index.php/bt 68 Figure 1 Environmental behaviors of Bt protein (A) and its three-dimensional structures (B) (Adopted from Li et al., 2022) Li et al. (2022) showed the behavior of Bt protein in the environment (A) and its three-dimensional structure (B). Bt plants introduce Bt protein into the soil through pollen deposition and residue regression. Bt protein binds to soil particles and is degraded by root exudates and microorganisms. Root exudates release metabolites that affect the microbial community in the soil. The three-dimensional structure of Bt protein (Cry2Aa) includes multiple functional regions that contribute to its binding and toxicity to target pests. This dynamic process shows that Bt plants not only have advantages in controlling pests, but also the persistence and degradation behavior of their metabolites and proteins in the soil need further study to evaluate their long-term impact on soil ecosystems. 5 Application Methods and Strategies 5.1 Field application techniques Field application techniques for Bt biopesticides are critical for maximizing their efficacy and sustainability. Traditional methods include foliar sprays, soil applications, and seed treatments. Foliar sprays are the most common, allowing for direct application to the plant surfaces where pests feed. Soil applications target root-feeding pests, while seed treatments provide early protection against pests during the vulnerable seedling stage. The effectiveness of these techniques can be influenced by environmental factors such as weather conditions and pest behavior. For instance, the use of transgenic Bt crops, which express Bt toxins throughout the plant, has been shown to reduce the need for additional insecticide applications and enhance pest control efficiency (Naranjo, 2011; Carrière et al., 2015; Kang et al., 2021). 5.2 Integrated pest management (IPM) Integrated Pest Management (IPM) is a holistic approach that combines multiple strategies to manage pest populations in an environmentally and economically sustainable manner. Bt biopesticides play a significant role in IPM programs by providing a biological control option that can be integrated with other methods such as crop rotation, use of natural predators, and chemical controls. The integration of Bt crops with IPM practices has been shown to reduce pest populations and insecticide use, thereby promoting ecological balance and reducing the risk of pest resistance (Naranjo, 2011; Martinez and Caprio, 2016; Anderson et al., 2019; Baker et al., 2020). For example, the use of Bt cotton has led to significant reductions in insecticide applications and has been a cornerstone in IPM strategies for cotton production (Manjunath, 2023).
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