Population Genetics of Ceratitis capitata in South Africa: Implications for Dispersal and Pest Management

The invasive Mediterranean fruit fly (medfly), Ceratitis capitata, is one of the major agricultural and economical pests globally. Understanding invasion risk and mitigation of medfly in agricultural landscapes requires knowledge of its population structure and dispersal patterns. Here, estimates of dispersal ability are provided in medfly from South Africa at three spatial scales using molecular approaches. Individuals were genotyped at 11 polymorphic microsatellite loci and a subset of individuals were also sequenced for the mitochondrial cytochrome oxidase subunit I gene. Our results show that South African medfly populations are generally characterized by high levels of genetic diversity and limited population differentiation at all spatial scales. This suggests high levels of gene flow among sampling locations. However, natural dispersal in C. capitata has been shown to rarely exceed 10 km. Therefore, documented levels of high gene flow in the present study, even between distant populations (>1600 km), are likely the result of human-mediated dispersal or at least some form of long-distance jump dispersal. These findings may have broad applicability to other global fruit production areas and have significant implications for ongoing pest management practices, such as the sterile insect technique.

入侵性地中海实蝇（Mediterranean fruit fly，简称medfly，学名*Ceratitis capitata*）是全球范围内主要的农业与经济害虫之一。解析农业景观中的地中海实蝇入侵风险并开展防控工作，需掌握其种群结构与扩散模式相关知识。本研究采用分子生物学方法，针对南非地中海实蝇种群，在三个空间尺度上对其扩散能力进行了评估。研究对象共在11个多态性微卫星位点（microsatellite loci）完成基因分型，其中部分个体还针对线粒体细胞色素氧化酶亚基I（mitochondrial cytochrome oxidase subunit I，COI）基因进行了测序。研究结果显示，南非地中海实蝇种群在所有空间尺度上均普遍表现出高水平的遗传多样性与有限的种群分化，这表明各采样位点间存在高水平的基因交流。不过，已有研究证实，地中海实蝇的自然扩散距离极少超过10公里。因此，本研究中观测到的高水平基因交流（即便采样种群间距超过1600公里），极有可能是人为介导的扩散所致，或至少存在某种形式的长距离跳跃式扩散。本研究结果可推广至全球其他水果产区，同时对包括昆虫不育技术（Sterile Insect Technique，SIT）在内的现行害虫防控实践具有重要指导意义。