Bt Research 2024, Vol.15, No.1, 30-41 http://microbescipublisher.com/index.php/bt 31 and resistance management. By synthesizing findings from multiple studies, the research seeks to provide a comprehensive understanding of the challenges and opportunities associated with the long-term sustainability of Bt transgenic crops in agriculture. 2 Agronomic Performance of Bt Crops 2.1 Yield benefits Bt transgenic crops have demonstrated significant yield benefits across various agricultural systems. The introduction of Bt crops, such as Bt cotton and Bt corn, has led to increased crop yields by effectively controlling target pests. For instance, Bt crops have been shown to increase yields by 22% on average, which has also resulted in a 68% increase in farmers' profits and a 37% reduction in chemical insecticide applications (Manjunath, 2020). This reduction in insecticide use not only lowers production costs but also minimizes environmental impact, contributing to the overall sustainability of agricultural practices (Siegfried and Jurat-Fuentes, 2016). 2.2 Pest resistance Despite the initial success of Bt crops in controlling pests, the evolution of pest resistance poses a significant challenge to their long-term sustainability. Studies have documented cases of practical resistance in several pest species. For example, resistance to Cry1F maize by the fall armyworm (Spodoptera frugiperda) has been reported in Puerto Rico, Brazil, and parts of the southeastern United States (Yang et al., 2016). Additionally, global monitoring data indicate an increase in pest resistance cases from 3 in 2005 to 26 in 2020, affecting multiple Bt toxins and pest species (Tabashnik and Carrière, 2017; Tabashnik et al., 2023). Factors such as recessive inheritance of resistance, low resistance allele frequency, and the use of multi-toxin Bt crops have been identified as critical in delaying resistance development (Carrière et al., 2015; Tabashnik and Carrière, 2017; Tabashnik et al., 2023). 2.3 Crop health and quality The health and quality of Bt crops are generally maintained or improved due to effective pest control. Bt crops have been associated with reduced crop damage and lower levels of mycotoxin contamination, which can occur when pests damage crops and create entry points for fungal infections (Xiao and Wu, 2019). Furthermore, Bt crops have been shown to promote biological control by conserving natural enemies of pests, such as parasitoids and predators, due to reduced insecticide use (Manjunath, 2020). This integrated pest management approach enhances the overall health and resilience of the crop ecosystem. Bt transgenic crops have provided substantial agronomic benefits, including increased yields, reduced reliance on chemical insecticides, and improved crop health and quality. However, the sustainability of these benefits is threatened by the evolution of pest resistance, necessitating ongoing monitoring and the implementation of effective resistance management strategies. 3 Environmental Impact 3.1 Biodiversity effects The introduction of Bt transgenic crops has raised concerns regarding their potential impact on biodiversity, particularly on non-target organisms. Studies have shown that Bt crops do not significantly affect the population abundance and biomass of soil invertebrates compared to conventional crops. A systematic review and meta-analysis of 22 publications revealed no significant effect of Cry proteins on soil invertebrates, although there was considerable variation among different orders of soil invertebrates (Krogh et al., 2020). Additionally, research on nematode communities indicated that Bt rice did not alter nematode abundance and community composition but did enhance trophic connections within nematode communities, suggesting a moderate stress effect of Cry proteins (Liu et al., 2018). Overall, while some studies suggest minor changes in specific taxa, the general consensus is that Bt crops do not pose a significant threat to soil biodiversity (Yaqoob et al., 2016; Mandal et al., 2020).
RkJQdWJsaXNoZXIy MjQ4ODYzNA==