Data from: Gene flow in the green mirid, Creontiades dilutus (Hemiptera: Miridae), across arid and agricultural environments with different host plant species

Creontiades dilutus (Stål), the green mirid, is a polyphagous herbivorous insect endemic to Australia. Although common in the arid interior of Australia and found on several native host plants that are spatially and temporally ephemeral, green mirids also reach pest levels on several crops in eastern Australia. These host-associated dynamics, distributed across a large geographic area, raise questions as to whether (1) seasonal fluctuations in population size result in genetic bottlenecks and drift, (2) arid and agricultural populations are genetically isolated, and (3) the use of different host plants results in genetic differentiation. We sequenced a mitochondrial COI fragment from individuals collected over 24 years and screened microsatellite variation from 32 populations across two seasons. The predominance of a single COI haplotype and negative Tajima D in samples from 2006/2007 fit with a population expansion model. In the older collections (1983 and 1993), a different haplotype is most prevalent, consistent with successive population contractions and expansions. Microsatellite data indicates recent migration between inland sites and coastal crops and admixture in several populations. Altogether, the data suggest that long-distance dispersal occurs between arid and agricultural regions, and this, together with fluctuations in population size, leads to temporally dynamic patterns of genetic differentiation. Host-associated differentiation is evident between mirids sampled from plants in the genus Cullen (Fabaceae), the primary host, and alternative host plant species growing nearby in arid regions. Our results highlight the importance of jointly assessing natural and agricultural environments in understanding the ecology of pest insects.

绿盲蝽（Creontiades dilutus (Stål)）是一种多食性植食性昆虫，为澳大利亚特有物种。该物种虽在澳大利亚干旱内陆区域广泛分布，且可寄生于多种时空分布短暂的本土寄主植物，但在澳大利亚东部的多种作物上也会达到害虫种群密度。这类分布于广阔地理范围的寄主关联种群动态，引发了三项核心科学议题：其一，种群规模的季节性波动是否会引发遗传瓶颈与遗传漂变；其二，干旱区域种群与农业区域种群是否存在遗传隔离；其三，不同寄主植物的利用是否会导致遗传分化。研究团队对24年间采集的昆虫个体进行了线粒体COI基因片段（mitochondrial COI fragment）测序，并对覆盖两个季节的32个种群的微卫星变异（microsatellite variation）进行了分型检测。2006/2007年的样本中，单一COI单倍型占据主导地位，且塔伊马D统计量（Tajima's D）为负值，这一结果符合种群扩张模型。而在较早的采集样本（1983年与1993年）中，另一种单倍型最为常见，这与连续的种群收缩-扩张模式相符。微卫星数据显示，内陆采样点与沿海作物种植区之间存在近期迁移事件，且多个种群存在遗传混合（admixture）现象。综合所有数据可知，干旱区域与农业区域之间存在长距离扩散（long-distance dispersal），结合种群规模的波动，共同造就了时空动态变化的遗传分化模式。在干旱区域，从主要寄主Cullen属（豆科（Fabaceae））植物以及周边替代寄主植物上采集的绿盲蝽之间，已观测到显著的寄主关联遗传分化。本研究结果凸显了联合评估自然与农业环境，对于解析害虫生态学的重要意义。