Novel RNA viruses in a commercial colony of Tenebrio molitor

Insect mass rearing for food and feed purposes is rapidly expanding in response to the current increase in protein demand. The mass reared insect strains are characterized by interactions with microorganisms, including viruses, that can be either beneficial or pathogenic and might lead to improved or decreased host health. The yellow mealworm, Tenebrio molitor, is a coleopteran species mainly reared for food and feed purposes showing high susceptibility to the Tenebrio molitor densovirus (TmDNV), which can lead to the loss of the entire population in a few days. The potential effect of viruses on mass-reared yellow mealworm highlights the need to screen for additional insect viruses associated with this insect species. In this study, we described and characterized five novel viruses associated with a European commercial T. molitor strain: Tenebrio molitor virga-like virus 1 (TmViLV1), Tenebrio molitor virga-like virus 2 (TmViLV2), Tenebrio molitor iflavirus 1 (TmIV1), Tenebrio molitor tombusvirus 1 (with two segments) (TmToV1), and Tenebrio molitor associated narnavirus 1 (TmAsNaV1). Then, we assessed the prevalence of these viruses in T. molitor samples derived from T. molitor rearings located worldwide. Assessing host-virus interactions aids in unravelling the effect of viruses on insect development, giving insights into possible implications for mass-rearing facilities.