Bt Research 2025, Vol.16, No.2, 55-62 http://microbescipublisher.com/index.php/bt 59 -helix removed also restored insecticidal effect in cadherin-mutated or silenced resistant Helicoverpa armigera and Aleyrodidae (Soberon et al., 2007). Some Bt toxins fused with new binding peptides showed higher fatality rates in different crops and pests (Deist et al., 2014). 6.3 Lessons learned and implications for sustainable pest control These successful cases demonstrate that a thorough understanding of the interaction mechanism between Bt toxins and receptors is crucial for antagonistic management. By targeting receptor mutation sites, optimizing toxin structures or expanding binding targets, pest resistance can be effectively overcome and the service life of Bt crops in the field can be prolonged (Soberón et al., 2007; Badran et al., 2016). However, resistance management requires a combination of multiple strategies, such as high-dose/shelter design, toxin pyramiding, and crop rotation, to slow the development of resistance (Wei et al., 2019). In the future, Bt toxin engineering should be combined with methods such as molecular monitoring and ecological management to jointly promote sustainable pest control systems (Deist et al., 2014; Afzal et al., 2024). 7 Ecological and Biosafety Considerations 7.1 Potential ecological impacts of engineered toxins on non-target organisms A large number of laboratory and field studies have shown that the current commercialized Bt crops have little direct negative impact on non-target organisms. This is mainly because the range of action of Bt toxin is relatively narrow. Some studies have even found that the use of Bt crops helps increase the number of beneficial insects, protects natural enemies, and thereby enhances the effect of biological control (Dhillon and Sharma, 2009; Yu et al., 2011). Field investigation results also show that the number and diversity of non-target arthropods in Bt corn and cotton fields are similar to those in non-Bt crop fields. Meanwhile, the promotion of Bt crops reduces the use of chemical pesticides, which is beneficial to both the environment and the health of farmers (Yu et al., 2011; Svobodova et al., 2015). However, Bt toxins can seep into the soil through root systems, which may affect the soil ecosystem. Although soil animals such as earthworms have not shown obvious toxic reactions, their role in the food chain still requires further research. In addition, risk assessment of non-target organisms usually relies on alternative species. How to select appropriate representative species to accurately predict ecological impacts remains a challenge (Carstens et al., 2013). 7.2 Gene flow and resistance management strategies in agroecosystems Resistance management is the key to whether Bt crops can be applied in the long term. The high-dose/refuge strategy requires planting a certain proportion of non-Bt crops near Bt crop fields to provide a non-toxic habitat for pests, thereby delaying the accumulation of resistance genes (Alphey et al., 2009; Arends et al., 2021). Studies have found that the proportion of refuges, their distribution locations, and the structure of surrounding crops (such as the proportion of soybeans and corn) all have an impact on the effectiveness of resistance management (Arends et al., 2021). Polytoxin gene pyramiding can expand the scope of prevention and control, but in the long term, it still needs to be combined with various measures such as shelters and crop rotation (Manyangarirwa et al., 2006; Wu, 2014). In addition, gene mobility not only refers to the spread of resistance genes among pest populations, but also includes gene exchange between genetically modified crops and wild relatives, which may have a profound impact on the structure of ecosystems. 7.3 Regulatory and public acceptance challenges At present, the ecological safety assessment and supervision system for Bt crops is gradually being improved. However, there are still knowledge gaps and uncertainties in aspects such as non-target biological effects, gene flow and resistance evolution (Reisig and Huseth, 2025). Regulatory authorities usually require developers to conduct a systematic assessment of the risks of non-target organisms, but how to balance scientific evidence, ecological complexity and practicality remains a difficult problem (Carstens et al., 2013). In addition, the public's acceptance of genetically modified crops is also influenced by multiple factors such as scientific communication, risk perception, and social culture. Maintaining the transparency and scientific nature of risk assessment and information disclosure is an important way to enhance social trust.
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