Bioprotection Aotearoa and Biochemistry Department, University of Otago, Dunedin, Aotearoa, New Zealand.
Humble Bee Bio, Wellington, Aotearoa, New Zealand.
BMC Genomics. 2023 Aug 5;24(1):440. doi: 10.1186/s12864-023-09538-4.
Biocontrol is a key technology for the control of pest species. Microctonus parasitoid wasps (Hymenoptera: Braconidae) have been released in Aotearoa New Zealand as biocontrol agents, targeting three different pest weevil species. Despite their value as biocontrol agents, no genome assemblies are currently available for these Microctonus wasps, limiting investigations into key biological differences between the different species and strains.
Here we present high-quality genomes for Microctonus hyperodae and Microctonus aethiopoides, assembled with short read sequencing and Hi-C scaffolding. These assemblies have total lengths of 106.7 Mb for M. hyperodae and 129.2 Mb for M. aethiopoides, with scaffold N50 values of 9 Mb and 23 Mb respectively. With these assemblies we investigated differences in reproductive mechanisms, and association with viruses between Microctonus wasps. Meiosis-specific genes are conserved in asexual Microctonus, with in-situ hybridisation validating expression of one of these genes in the ovaries of asexual Microctonus aethiopoides. This implies asexual reproduction in these Microctonus wasps involves meiosis, with the potential for sexual reproduction maintained. Investigation of viral gene content revealed candidate genes that may be involved in virus-like particle production in M. aethiopoides, as well as a novel virus infecting M. hyperodae, for which a complete genome was assembled.
These are the first published genomes for Microctonus wasps which have been deployed as biocontrol agents, in Aotearoa New Zealand. These assemblies will be valuable resources for continued investigation and monitoring of these biocontrol systems. Understanding the biology underpinning Microctonus biocontrol is crucial if we are to maintain its efficacy, or in the case of M. hyperodae to understand what may have influenced the significant decline of biocontrol efficacy. The potential for sexual reproduction in asexual Microctonus is significant given that empirical modelling suggests this asexual reproduction is likely to have contributed to biocontrol decline. Furthermore the identification of a novel virus in M. hyperodae highlights a previously unknown aspect of this biocontrol system, which may contribute to premature mortality of the host pest. These findings have potential to be exploited in future in attempt to increase the effectiveness of M. hyperodae biocontrol.
生物防治是控制害虫物种的关键技术。微蜂寄生蜂（膜翅目：Braconidae）已作为生物防治剂在新西兰奥特亚罗瓦释放，针对三种不同的害虫象鼻虫。尽管它们作为生物防治剂具有价值，但目前尚无这些微蜂的基因组组装，限制了对不同物种和菌株之间关键生物学差异的研究。
在这里，我们为 Microctonus hyperodae 和 Microctonus aethiopoides 提供了高质量的基因组，这些基因组是使用短读测序和 Hi-C 支架组装的。这些组装的总长度分别为 106.7 Mb 和 129.2 Mb，支架 N50 值分别为 9 Mb 和 23 Mb。利用这些组装，我们研究了微蜂生殖机制和与病毒的关联的差异。减数分裂特异性基因在无性的 Microctonus 中保守，原位杂交验证了这些基因之一在无性 Microctonus aethiopoides 的卵巢中的表达。这意味着这些微蜂的无性繁殖涉及减数分裂，同时保持了有性繁殖的潜力。病毒基因含量的调查揭示了可能参与 M. aethiopoides 病毒样颗粒产生的候选基因，以及感染 M. hyperodae 的一种新病毒，该病毒的完整基因组已组装。
这些是在新西兰奥特亚罗瓦部署为生物防治剂的 Microctonus 蜂的第一批已发表基因组。这些组装将是继续研究和监测这些生物防治系统的宝贵资源。如果我们要维持其功效，或者了解 M. hyperodae 中可能影响生物防治功效显著下降的原因，那么了解 Microctonus 生物防治的生物学基础至关重要。无性 Microctonus 中存在有性繁殖的可能性非常重要，因为实证模型表明这种无性繁殖可能促成了生物防治的衰退。此外，在 M. hyperodae 中发现一种新病毒突出了这种生物防治系统的一个以前未知的方面，这可能导致宿主害虫过早死亡。这些发现有可能在未来被利用，以试图提高 M. hyperodae 生物防治的效果。
