A "male-killing" virus that is transmitted from insect mothers to eggs and stops the male development has been discovered in a species of Drosophila (fly), and the genome structure of the virus has been determined. This is the first time that a male-killing gene has been identified in a virus. Given the existence of closely related viruses in a variety of insects, we anticipate that viruses with similar functions will be discovered in the near future. The elucidation of the male-killing mechanism will contribute to a comprehensive understanding of the insect sex-determining system, the development of insect pest control, and improvement of natural enemy of pest insects by controlling sex.
Overview
Insects are known to harbor a variety of microbes living in their cells that are passed on from mother to offspring. Symbiotic microorganisms, especially Wolbachia bacteria, can manipulate the reproduction of their hosts in various ways for their own benefit, such as "male killing", killing only male insects at the embryonic stage, and "feminization", changing the phenotype of genetic males into females. Much attention has therefore been focused on the mechanism and its application.
A research group led by the National Agriculture and Food Research Organization (NARO) and Ehime University has discovered a male-killing strain of the fly Drosophila biauraria. Initially, symbiotic bacteria such as Wolbachia were suspected as the cause of the male killing, but the presence of bacteria could not be confirmed. Further analysis of this strain revealed that the cause of the male killing was a double-stranded RNA virus closely related to the family Partitiviridae. Then, with the cooperation of researchers from Kyoto University, Gunma University, and the National Institute of Health Sciences (NIHS), it was clarified that this virus has only four genes, one of which is responsible for male killing.
As symbiotic viruses of insects are unexplored resources, various discoveries and applications are expected in the future. In addition, the analysis of the male-killing gene discovered this time will not only lead to a deeper understanding of the sex-determining machinery of insects and the interaction between insects and viruses, but it is also expected to be useful for the development of new pest control technology and for the improvement of natural enemies of pests by controlling sex.
Publication
A male-killing gene encoded by a symbiotic virus of Drosophila. Daisuke Kageyama, Toshiyuki Harumoto, Keisuke Nagamine, Akiko Fujiwara, Takafumi N. Sugimoto, Akiya Jouraku, Masaru Tamura, Takehiro K. Katoh, Masayoshi Watada. Nature Communications. Doi: https://www.nature.com/articles/s41467-023-37145-0
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