Optimization of screening methods leads to the discovery of new viruses in black soldier flies (Hermetia illucens)

Virus discovery in mass-reared insects is a growing topic of interest due to outbreak risks and for insect welfare concerns. In the case of black soldier flies (BSF), pioneering bioinformatic studies have uncovered exogenous viruses from the orders Ghabrivirales and Bunyavirales, as well as endogenous viral elements from five virus families. This prompted further virome investigation of BSF metagenomes and metatranscriptomes, including from BSF individuals displaying signs and symptoms of disease. In this study, we describe five newly discovered viruses from the families Dicistroviridae, Iflaviridae, Rhabdoviridae, Solinviviridae, and Inseviridae. These viruses were detected in BSF from multiple origins, outlining a diversity of naturally occurring viruses associated with BSF. This viral community may also include BSF pathogens. The growing list of viruses found in BSF allowed the development of molecular detection tools which could be used for viral surveillance, both in mass-reared and wild populations of BSF.