Tanaka T, Tagashira E
Laboratory of Applied Entomology, School of Agricultural Sciences, Nagoya University, Chikusa, Nagoya, Japan
J Insect Physiol. 1998 Sep;44(9):733-744. doi: 10.1016/s0022-1910(98)00006-7.
Parasitization by the endoparasitoid Cotesia kariyai caused the inhibition of spermatogenesis of Pseudaletia separata. This phenomenon is called parasitic castration. The degree of castration was dependent on the host stage parasitized. Host parasitized on day 1 of the 4th stadium (the time of primary spermatocyte accumulation), had testicular cells with abnormal chromosomes appearing two days after parasitization, and spermiogenesis was completely inhibited. However, when hosts were parasitized on day 0 of the 6th (final) stadium, the degree of castration was less severe, and elongated cells appeared similar to those found in nonparasitized larvae. Results of this study involving injection of C. kariyai polydnavirus (CkPV) and venom suggested that these wasp components caused the appearance of abnormal chromosomes in specific germ cells, which were in mitotic or meiotic prophases. The amount of CkPV gene expression in host testes increased immediately after parasitization and reached a maximum 12h later. The early-expressed CkPV gene(s) may be related to the parasitic castration phenomenon.
内寄生蜂甘蓝夜蛾小腹茧蜂（Cotesia kariyai）的寄生会抑制粘虫（Pseudaletia separata）的精子发生。这种现象被称为寄生去势。去势程度取决于被寄生的宿主阶段。在四龄第一天（初级精母细胞积累期）被寄生的宿主，在寄生两天后睾丸细胞出现染色体异常，精子发生被完全抑制。然而，当宿主在六龄（最后一龄）第一天被寄生时，去势程度较轻，出现了与未被寄生幼虫中相似的伸长细胞。这项涉及注射甘蓝夜蛾小腹茧蜂多角体病毒（CkPV）和毒液的研究结果表明，这些黄蜂成分导致特定生殖细胞中出现异常染色体，这些细胞处于有丝分裂或减数分裂前期。寄生后宿主睾丸中CkPV基因表达量立即增加，并在12小时后达到最大值。早期表达的CkPV基因可能与寄生去势现象有关。
