School of Agriculture, Policy and Development, University of Reading, Reading, UK.
Department of Public Governance and Sustainable Development, MODUL University, Vienna, Austria.
Plant Biotechnol J. 2015 Jun;13(5):601-12. doi: 10.1111/pbi.12363. Epub 2015 Mar 31.
The intensification of agriculture and the development of synthetic insecticides enabled worldwide grain production to more than double in the last third of the 20th century. However, the heavy dependence and, in some cases, overuse of insecticides has been responsible for negative environmental and ecological impacts across the globe, such as a reduction in biodiversity, insect resistance to insecticides, negative effects on nontarget species (e.g. natural enemies) and the development of secondary pests. The use of recombinant DNA technology to develop genetically engineered insect-resistant crops could mitigate many of the negative side effects of insecticides. One such genetic alteration enables crops to express toxic crystalline (Cry) proteins from the soil bacteria Bacillus thuringiensis (Bt). Despite the widespread adoption of Bt crops, there are still a range of unanswered questions concerning longer term agro-ecosystem interactions. For instance, insect species that are not susceptible to the expressed toxin can develop into secondary pests and cause significant damage to the crop. Here, we review the main causes surrounding secondary pest dynamics in Bt crops and the impact of such outbreaks. Regardless of the causes, if nonsusceptible secondary pest populations exceed economic thresholds, insecticide spraying could become the immediate solution at farmers' disposal, and the sustainable use of this genetic modification technology may be in jeopardy. Based on the literature, recommendations for future research are outlined that will help to improve the knowledge of the possible long-term ecological trophic interactions of employing this technology.
农业集约化和合成杀虫剂的发展使全球粮食产量在 20 世纪最后三分之一的时间里增长了一倍多。然而，对杀虫剂的严重依赖和在某些情况下的过度使用，已经对全球的环境和生态造成了负面影响，例如生物多样性减少、昆虫对杀虫剂的抗药性、对非目标物种（如天敌）的负面影响以及次生害虫的发展。利用重组 DNA 技术开发基因工程抗虫作物可以减轻杀虫剂的许多负面影响。一种这样的遗传改变使作物能够表达来自土壤细菌苏云金芽孢杆菌（Bt）的有毒晶体（Cry）蛋白。尽管 Bt 作物得到了广泛的采用，但关于长期农业生态系统相互作用仍有一系列尚未解决的问题。例如，对表达的毒素不易感的昆虫物种可能会演变成次生害虫，并对作物造成重大损害。在这里，我们回顾了 Bt 作物中次生害虫动态的主要原因以及此类爆发的影响。无论原因是什么，如果不易感的次生害虫种群超过经济阈值，农民可能会立即使用杀虫剂喷洒来解决问题，而这种遗传修饰技术的可持续利用可能会受到威胁。根据文献，概述了未来研究的建议，这将有助于提高对采用这项技术可能产生的长期生态营养相互作用的认识。
