Discovery and localization of a type 5 cypovirus in Heliothis virescens and Campoletis sonorensis host-parasitoid system

Some viruses, notably the ascoviruses, are reliant upon parasitoid wasps for horizontal transmission between their lepidopteran hosts. Other viruses, the polydnaviruses, are obligate symbionts of parasitoid wasps, existing in highly commensal and evolved relationships with their parasitoid hosts. Still other viruses have been described from the reproductive tracts of female parasitoid wasps but their roles remain unclear. We have recently discovered a Type 5 cypovirus in both a parasitoid wasp, the Campoletis sonorensis and in the wasp’s conventional host, Heliothis virescens larvae. Among the viruses associated with parasitoid wasps, polydnaviruses are considered beneficial and are essential aids to wasps in the parasitism of their lepidopteran host. In contrast, the impact of ascoviruses within the wasp-host system can be detrimental to both the wasp and its lepidopteran host as both the parasitized lepidopteran larvae and the larval wasp parasite usually die as a result of ascovirus infections. Unlike these viruses, small RNA viruses such as cypoviruses have little overt effect on their lepidopteran host while the impact of cypovirus infection on wasp parasites has not been examined. We describe here a novel virus, in the genus cypovirus, which appears to interact with the polydnavirus and its wasp host in a fundamentally new and intriguing way.