Sisterson Mark S, Carrière Yves, Dennehy Timothy J, Tabashnik Bruce E
Department of Entomology, University of Arizona, Tucson, AZ 85721, USA.
J Econ Entomol. 2005 Dec;98(6):1751-62. doi: 10.1093/jee/98.6.1751.
The refuge strategy is designed to delay evolution of pest resistance to transgenic crops producing Bacillus thuringiensis Berliner (Bt) toxins. Movement of insects between Bt crops and refuges of non-Bt crops is essential for the refuge strategy because it increases chances that resistant adults mate with susceptible adults from refuges. Conclusions about optimal levels of movement for delaying resistance are not consistent among previous modeling studies. To clarify the effects of movement on resistance evolution, we analyzed simulations of a spatially explicit model based partly on the interaction of pink bollworm, Pectinophora gossypiella (Saunders), with Bt cotton. We examined resistance evolution as a function of insect movement under 12 sets of assumptions about the relative abundance of Bt cotton (50 and 75%), temporal distribution of Bt cotton and refuge fields (fixed, partial rotation, and full rotation), and spatial distribution of fields (random and uniform). The results show that interactions among the relative abundance and distribution of refuges and Bt cotton fields can alter the effects of movement on resistance evolution. The results also suggest that differences in conclusions among previous studies can be explained by differences in assumptions about the relative abundance and distribution of refuges and Bt crop fields. With fixed field locations and all Bt cotton fields adjacent to at least one refuge, resistance evolved slowest with low movement. However, low movement and fixed field locations favored rapid resistance evolution when some Bt crop fields were isolated from refuges. When refuges and Bt cotton fields were rotated to the opposite crop type each year, resistance evolved fastest with low movement. Nonrecessive inheritance of resistance caused rapid resistanceevolution regardless of movement rate. Confirming previous reports, results described here show that resistance can be delayed effectively by fixing field locations and distributing refuges uniformly to ensure that Bt crop fields are not isolated from refuges. However, rotating fields provided better insect control and reduced the need for insecticide sprays.
避难所策略旨在延缓害虫对产生苏云金芽孢杆菌（Bt）毒素的转基因作物产生抗性的进化过程。昆虫在Bt作物和非Bt作物避难所之间的移动对于避难所策略至关重要，因为这增加了抗性成虫与来自避难所的易感成虫交配的机会。关于延缓抗性的最佳移动水平的结论在先前的建模研究中并不一致。为了阐明移动对抗性进化的影响，我们分析了一个空间明确模型的模拟结果，该模型部分基于棉铃虫（Pectinophora gossypiella (Saunders)）与Bt棉花的相互作用。我们在关于Bt棉花相对丰度（50%和75%）、Bt棉花和避难所田地的时间分布（固定、部分轮作和完全轮作）以及田地空间分布（随机和均匀）的12组假设下，研究了抗性进化作为昆虫移动的函数。结果表明，避难所和Bt棉花田的相对丰度及分布之间的相互作用可以改变移动对抗性进化的影响。结果还表明，先前研究结论的差异可以通过关于避难所和Bt作物田相对丰度及分布假设的差异来解释。在田地位置固定且所有Bt棉花田都与至少一个避难所相邻的情况下，低移动时抗性进化最慢。然而，当一些Bt作物田与避难所隔离时，低移动和固定的田地位置有利于抗性快速进化。当避难所和Bt棉花田每年轮换种植相反的作物类型时，低移动时抗性进化最快。抗性的非隐性遗传导致无论移动速率如何，抗性都快速进化。正如先前报道所证实的，此处描述的结果表明，通过固定田地位置和均匀分布避难所，以确保Bt作物田不与避难所隔离，可以有效地延缓抗性。然而，轮作田地能提供更好的害虫控制，并减少杀虫剂喷洒的需求。
