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Abstract：
In Hymenoptera species, the reproductive mode is usually arrhenotoky, where haploid males arise from unfertilized eggs and diploid females from fertilized eggs. In addition, a few species reproduce by thelytoky, where diploid females arise from unfertilized eggs. Diploid females can be derived through various cytological mechanisms in thelytokous Hymenoptera species. Hitherto, these mechanisms were revealed mainly in endosymbiont-induced thelytokous Hymenoptera species. In contrast, thelytokous Hymenoptera species in which a reproductive manipulator has not been verified or several common endosymbionts have been excluded were paid less attention in their cytological mechanisms, for instance, Diglyphus wani (Hymenoptera: Eulophidae). Here, we investigated the cytological mechanism of D. wani using cytological methods and genetic markers. Our observations indicated that the diploid karyotypes of two strains of D. wani consist of four pairs of relatively large metacentric chromosomes and one pair of short submetacentric chromosomes (2n = 10). The arrhenotokous strains could complete normal meiosis, whereas the thelytokous strain lacked meiosis and did not expulse any polar bodies. This reproductive type of lacking meiosis is classified as apomictic thelytoky. Moreover, a total of 636 microsatellite sequences were obtained from thelytokous D. wani, dominated by dinucleotide repeats. Genetic markers results showed all three generations of offspring from thelytokous strain maintained the same genotype as their parents. Our results revealed that D. wani is the first eulophid parasitoid wasp in Hymenoptera whose thelytoky was not induced by bacteria to form an apomictic thelytoky. These findings provide a baseline for future inner molecular genetic studies of ameiotic thelytoky.
摘要：
在膜翅目物种中，生殖模式通常是arrenotoky，单倍体雄性来自未受精卵，二倍体雌性来自受精卵。此外,一些物种通过thelytoky繁殖，二倍体雌性来自未受精卵。二倍体雌性可以通过各种细胞学机制在膜翅目物种中产生。到目前为止，这些机制主要在内共生体诱导的膜翅目昆虫物种中揭示。相比之下,尚未证实生殖操纵器或排除了几种常见的内共生体的膜翅目物种在细胞学机制上的关注较少。例如,Diglyphuswani（膜翅目：Eulophidae）。这里,我们使用细胞学方法和遗传标记研究了D.wani的细胞学机制。我们的观察表明，两个D.wani菌株的二倍体核型由四对相对较大的中心染色体和一对较短的亚中心染色体组成（2n=10）。触感菌株可以完成正常的减数分裂，而细胞因子缺乏减数分裂，并且没有驱逐任何极体。这种缺乏减数分裂的生殖类型被归类为无融合生殖。此外，总共有636个微卫星序列从毒性D.wani获得，以二核苷酸重复为主。遗传标记结果表明，来自该毒株的所有三代后代均保持与父母相同的基因型。我们的结果表明，D.wani是膜翅目中的第一只杂虫类黄蜂，其细胞未被细菌诱导形成无融合生殖细胞。这些发现为将来的无性系细胞内分子遗传研究提供了基线。
