Bt Research 2024, Vol.15, No.2, 87-95 http://microbescipublisher.com/index.php/bt 87 Feature Review Open Access Eclgical Impact of Bt on Non-target Invertebrates SibinWang Hainan Institute of Tropical Agricultural Resources (HITAR), Tropical Animal Resources Research Center, Sanya, 572025, Hainan, China Corresponding email: sibin.wang@hitar.org Bt Research, 2024, Vol.15, No.2 doi: 10.5376/bt.2024.15.0009 Received: 20 Feb., 2024 Accepted: 30 Mar., 2024 Published: 18 Apr., 2024 Copyright © 2024 Wang, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Wang S.B., 2024, Eclgical impact of Bt on non-target invertebrates, Bt Research, 15(2): 87-95 (doi: 10.5376/bt.2024.15.0009) Abstract The ecological impact of Bacillus thuringiensis (Bt) crops on non-target invertebrates has been a subject of extensive research and debate. This study synthesizes findings from multiple studies to provide a comprehensive understanding of the effects of Bt crops on non-target invertebrate populations. Meta-analyses indicate that non-target invertebrates are generally more abundant in Bt crop fields compared to non-transgenic fields managed with insecticides, although certain taxa are less abundant in Bt fields compared to insecticide-free control fields. Laboratory and field studies reveal that Bt crops have varying impacts on non-target Lepidoptera, with some species showing adverse effects under laboratory conditions, while field studies often report minimal impacts. The presence of Bt proteins in soil and their potential effects on soil-dwelling organisms, such as earthworms, have also been investigated, with findings suggesting no deleterious effects on growth and reproduction. Additionally, the coexistence of Bt and conventional crops can influence insect abundance and plant fitness, with Bt crops providing benefits by reducing target insect populations and thereby enhancing the growth of non-transgenic plants. Despite these findings, the long-term ecological risks and the potential for resistance development in target pests remain areas of concern that require ongoing monitoring and research. This study underscores the importance of evidence-based risk assessments and the need for more ecologically realistic studies to fully understand the ecological implications of Bt crop cultivation. Keywords Bt crops; Non-target invertebrates; Ecological impact; Resistance development; Soil-dwelling organisms 1 Introduction Bacillus thuringiensis (Bt) is a gram-positive bacterium that produces crystal proteins (Cry proteins) during sporulation, which are toxic to specific insect orders such as Lepidoptera, Coleoptera, and Diptera. These proteins have been harnessed in agriculture through the development of Bt transgenic crops, which express these insecticidal proteins to protect against pest infestations. Bt crops, such as Bt maize and Bt cotton, have been widely adopted globally due to their effectiveness in reducing pest populations and minimizing the need for chemical insecticides (Clark et al., 2005; Marvier et al., 2007; Li et al., 2022). While Bt crops offer significant benefits in pest management, there is growing concern about their potential impacts on non-target invertebrates. Non-target organisms, which are not the intended recipients of the Bt toxins, may be exposed to these proteins through various environmental pathways, including soil, water, and plant residues. Understanding the ecological consequences of Bt crops on non-target invertebrates is crucial for several reasons. Firstly, non-target invertebrates play essential roles in ecosystem functioning, including pollination, decomposition, and as part of the food web. Secondly, assessing the non-target impacts of Bt crops is vital for ensuring the sustainability and environmental safety of this technology (Clark et al., 2005; Lang and Otto, 2010; Caquet et al., 2011). This study aims to summarize the findings from field and laboratory studies on the impact of Bt crops on non-target invertebrate populations. It evaluates the methodologies used in these studies to assess the non-target effects of Bt crops. By identifying knowledge gaps and areas needing further research, this review seeks to enhance our understanding of the ecological risks associated with Bt crops. Additionally, the study offers recommendations for future research and risk assessment practices to ensure the safe and sustainable use of Bt technology in agriculture. By achieving these objectives, this review aims to contribute to evidence-based risk analysis and inform regulatory decisions regarding the application of Bt crops in agricultural systems.
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