陕西省赤眼蜂调查并记述—新种(膜翅目:纹翅小蜂科)

在陕西省调查采集的赤眼蜂,经制片整理共有10种,其中有1个新种。新种的模式标本保存于陕西省植保所。现列名录如下: 螟黄赤眼蜂 Trichogramna chilonis Ishii 舟蛾赤眼蜂 T.closterae Pang et Chen 松毛虫赤眼蜂 T.dendrolimi Matsumura 广赤眼蜂 T.evanescens Westwood 毒蛾赤眼蜂 T.ivelae Pang et Chen 稻螟赤眼蜂 T.japonicum Ashmead     

The origin of a selfish B chromosome triggering paternal sex ratio in the parasitoid wasp Trichogramma kaykai

This study uses molecular and cytogenetic methods to determine the origin of a B chromosome in some males of the wasp Trichogramma kaykai. This so-called paternal sex ratio (PSR) chromosome transmits only through sperm and shortly after fertilization triggers degeneration of the paternal genome, while keeping itself intact. The resulting embryos develop into haploid B-chromosome-carrying males. Another PSR chromosome with a very similar mode of action is found in the distantly related wasp Nasonia vitripennis and its origin was traced by transposon similarity to the genus Trichomalopsis, which is closely related to Nasonia. To determine whether both PSR chromosomes have a similar origin we aimed to reveal the origin of the Trichogramma PSR chromosome. Using fluorescent in situ hybridization, we discovered a major satellite repeat on the PSR chromosome, the 45S ribosomal DNA. Analysis of the internal transcribed spacer 2 (ITS2) of this repeat showed the presence of multiple ITS2 sequences on the PSR chromosome resembling either the ITS2 of T. oleae or of T. kaykai. We therefore conclude that the Trichogramma PSR chromosome originates from T. oleae or a T. oleae-like species. Our results are consistent with different origins for the PSR chromosomes in Trichogramma and Nasonia.