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A novel negative-stranded RNA virus mediates sex ratio in its parasitoid host

Editor:admin Date:2017-03-17 Hits:150

Parasitoid wasps are important natural enemies of arthropod hosts in natural and agricultural ecosystems. They are often associated with viruses or virion-like particles to suppress immune responses and manipulate development as well as growth of pest hosts. However, there is no literature previously reporting that a virus mediates sex ratio in the host wasp. Professor Gongyin Ye’s research group in Institute of Insect Sciences, College of Agriculture and Biotechnology, Zhejiang University, discovers a novel negative-stranded RNA virus from a parasitoid wasp (Pteromalus puparum). Here we designate the novel virus as Pteromalus puparum negative-strand RNA virus 1 (PpNSRV-1).  PpNSRV-1 mediates the offspring sex ratio by decreasing female offspring numbers. This highlight article was published by PLoS Pathgens, a pathological top journal, as the featured research, on 9 March, 2017. Meanwhile, the research paper was also reported by EurekAlert (sponsored by The American Association for the Advancement of Science) as a press release, using the title of “Newly discovered virus affects sex ratio of insect-killing wasps”. Fei Wang, a Ph. D. candidate, and Dr. Qi Fang are the co-first authors, and Professors Gongyin Ye from Zhejiang University as well as Qisheng Song from University of Missouri are the co-corresponding authors. This research is supported by the grants of National Natural Science Foundation of China and China National Program on Key Basic Research Projects.

The results show that the complete viral genome is 12,230 nucleotides in length, containing five non-overlapping, linearly arranged open reading frames. Phylogenetically, the virus clusters with and is a novel member (a novel genus) of the mononegaviral family Nyamiviridae. The taxonomy information is confirmed by International Committee on Taxonomy of Viruses. PpNSRV-1 is present in various tissues and life stages of the parasitoid wasp, and is transmitted vertically through infected females and males. Virus infections in field populations of P. puparum wasps ranged from 16.7 to 37.5%, without linearly correlating with temperature. Comparative results between virus infected and non-infected strains and RNA interference verification represent that PpNSRV-1 increased adult longevity and impaired several fitness parameters of the wasp, but had no influence on successful parasitism. Strikingly, PpNSRV-1 mediated the offspring sex ratio by decreasing female offspring numbers. This point is so different from the typical theory of insect sex ratio regulated by symbiotic bacterium. This research is the first case to show a virus mediating insect sex ratio. These results possess the valuable information for increasing the usage rate of parasitoid wasps on pest control and studying on the co-evolutionary relationships between viruses and their hosts.

(Institute of Insect Sciences)

Article linkage in PLoS Pathogens

Press release linkage in EurekAlert