Cross-Mating Compatibility and Competitiveness among <i>Aedes albopictus</i> Strains from Distinct Geographic Origins - Implications for Future Application of SIT Programs in the South West Indian Ocean Islands

The production of large numbers of males needed for a sustainable sterile insect technique (SIT) control program requires significant developmental and operational costs. This may constitute a significant economic barrier to the installation of large scale rearing facilities in countries that are undergoing a transition from being largely dependent on insecticide use to be in a position to integrate the SIT against Aedes albopictus. Alternative options available for those countries could be to rely on outsourcing of sterile males from a foreign supplier, or for one centralised facility to produce mosquitoes for several countries, thus increasing the efficiency of the mass-rearing effort. However, demonstration of strain compatibility is a prerequisite for the export of mosquitoes for transborder SIT applications. Here, we compared mating compatibility among Ae. albopictus populations originating from three islands of the South Western Indian Ocean, and assessed both insemination rates and egg fertility in all possible cross-mating combinations. Furthermore, competitiveness between irradiated and non-irradiated males from the three studied strains, and the subsequent effect on female fertility were also examined. Although morphometric analysis of wing shapes suggested phenoptypic differences between Ae. albopictus strains, perfect reproductive compatibility between them was observed. Furthermore, irradiated males from the different islands demonstrated similar levels of competitiveness and induced sterility when confronted with fertile males from any of the other island populations tested. In conclusion, despite the evidence of inter-strain differences based on male wing morphology, collectively, our results provide a new set of expectations for the use of a single candidate strain of mass-reared sterile males for area-wide scale application of SIT against Ae. albopictus populations in different islands across the South Western Indian Ocean. Cross-mating competitiveness tests such as those applied here are necessary to assess the quality of mass reared strains for the trans-border application of sterile male release programs.可持续昆虫不育技术（Sterile Insect Technique, SIT）防控项目所需的大规模雄虫繁育工作，需承担高昂的研发与运营成本。对于正从主要依赖杀虫剂防控，转向整合SIT防控白纹伊蚊（Aedes albopictus）的国家而言，这类成本可能成为其建设大规模繁育设施的重大经济壁垒。针对这类国家，可行的替代方案包括从境外供应商外包不育雄虫，或是由一家集中化繁育中心为多国提供蚊虫，以此提升大规模繁育工作的效率。然而，针对跨境SIT应用的蚊虫出口，品系兼容性验证是必要前提。本研究针对西南印度洋三座岛屿的白纹伊蚊种群，比较了其交配兼容性，并评估了所有可能杂交组合的授精率与卵育性。此外，本研究还检测了三个受试品系的辐照雄虫与未辐照雄虫间的竞争能力，及其对雌虫繁育力的后续影响。尽管翅形的形态计量分析显示不同白纹伊蚊品系间存在表型差异，但各品系间均表现出完全的生殖兼容性。此外，来自不同岛屿的辐照雄虫，在与其他受试岛屿种群的可育雄虫共存时，均展现出相近的竞争能力与不育诱导效果。综上，尽管基于雄虫翅形的分析证实了品系间存在差异，但综合来看，本研究结果为使用单一候选大规模繁育不育雄虫品系，在西南印度洋不同岛屿开展针对白纹伊蚊种群的区域规模化SIT应用提供了新的预期。类似本研究开展的杂交竞争兼容性检测，对于评估用于跨境不育雄虫释放项目的大规模繁育品系质量而言，是必要的环节。