Data from: The application of self-limiting transgenic insects in managing resistance in experimental metapopulations

1. The mass release of transgenic insects carrying female lethal self-limiting genes can reduce pest insect populations. Theoretically, substantial releases can be a novel resistance management tool, since wild type alleles conferring susceptibility to pesticides can dilute resistance alleles in target populations. A potential barrier to the deployment of this technology is the need for large-scale area wide releases. Here we address whether localized releases of transgenic insects could provide an alternative, means of population suppression and resistance management, without serious loss of efficacy. 2. We used experimental mesocosms constituting insect metapopulations to explore the evolution of resistance to the Bacillus thuringiensis toxin Cry1Ac in a high-dose/refugia landscape in the insect Plutella xylostella. We ran two selection experiments, the first compared the efficacy of 'everywhere' releases and negative controls to a spatially density-dependent or 'whack-a-mole' strategy that concentrated release of transgenic insects in sub-populations with high levels of resistance. The second experiment tested the relative efficacy of whack-a-mole and everywhere releases under spatially homogenous and heterogeneous selection pressure. 3. The whack-a-mole releases were less effective than everywhere releases in terms of slowing the evolution of resistance, which in the first experiment, largely prevented the evolution of resistance. In contrast to predictions, heterogeneous whack-a-mole releases were not more effective under heterogeneous selection pressure. Heterogeneous selection pressure did, however, reduce total insect population sizes 4. Whack-a-mole releases provided early population suppression that was indistinguishable from homogeneous everywhere releases. However, insect population densities tracked the evolution of resistance in this system, as phenotypic resistance provides access to the 90% of experimental diet containing the toxin Cry1Ac. Thus, as resistance levels diverged between treatments, carrying capacities diverged and population sizes increased under the whack- a-mole approach. Synthesis and Applications Spatially density-dependent releases of transgenic insects, particularly those targeting source populations at landscape level, could suppress pest populations in the absence of blanket area-wide management. The resistance management benefits of self-limiting transgenic insects are, however, reduced in spatially localized releases, suggesting that they are not best suited for spatially restricted 'spot' treatment of problematic resistance. Nevertheless, area-wide and spatially heterogeneous releases could be used to support other resistance management interventions.

1. 携带雌性致死自限基因（female lethal self-limiting genes）的转基因昆虫（transgenic insects）大规模释放可降低害虫种群（pest insect populations）数量。理论上，大规模释放可作为一种新型抗性治理工具（resistance management tool），因为可使靶标种群中对杀虫剂敏感的野生型等位基因（wild type alleles）稀释抗性等位基因（resistance alleles）。该技术的应用存在一项潜在障碍：需在大范围内开展大规模释放。本研究旨在探讨，局部释放转基因昆虫能否作为种群抑制与抗性治理的替代方案，且不会显著损失防控效果。
2. 我们利用构成昆虫集合种群（insect metapopulations）的实验中宇宙系统（experimental mesocosms），在小菜蛾（Plutella xylostella）的高剂量/庇护所景观（high-dose/refugia landscape）中，探究其对苏云金杆菌（Bacillus thuringiensis）毒素Cry1Ac的抗性演化过程。本研究开展两组选择实验：第一组对比“全域”释放、阴性对照，以及空间密度依赖型（或称“打地鼠”）释放策略的防控效果——后者将转基因昆虫集中释放至抗性水平较高的亚种群中。第二组实验则在空间均质（spatially homogenous）与异质选择压力（heterogeneous selection pressure）下，对比打地鼠策略与全域释放的相对防控效果。
3. 就延缓抗性演化而言，打地鼠释放策略的效果逊于全域释放策略；在第一组实验中，全域释放基本阻止了抗性的演化。与理论预测相悖的是，异质选择压力下的异质打地鼠释放并未表现出更优的防控效果。不过，异质选择压力确实降低了昆虫总种群规模。
4. 打地鼠释放在早期可实现与均质全域释放无显著差异的种群抑制效果。但在此系统中，昆虫种群密度随抗性演化动态变化：表型抗性（phenotypic resistance）可使昆虫取食含90%Cry1Ac毒素的实验饲料。因此，随着不同处理组间抗性水平出现分化，环境容纳量（carrying capacities）也随之改变，打地鼠策略下的种群规模逐渐上升。
总结与应用：空间密度依赖型转基因昆虫释放，尤其是针对景观尺度源种群的释放，可在无需全域大范围防控的情况下实现害虫种群抑制。但局部释放的自限转基因昆虫的抗性治理效益会有所降低，这表明此类释放策略并不适用于针对抗性问题的空间定点处理。不过，全域释放与空间异质释放可用于辅助其他抗性治理措施。