First Evidence of Past and Present Interactions between Viruses and the Black Soldier Fly, Hermetia illucens
Robert D Pienaar1,2, Clément Gilbert3, Carole Belliardo3
1Institut de Recherche sur la Biologie de l'Insecte, UMR 7261 CNRS-Université de Tours, 37200 Tours, France.
Abstract:
Black soldier flies (BSFs, Hermetia illucens) are becoming a prominent research model encouraged by the insect as food and feed and waste bioconversion industries. Insect mass-rearing facilities are at risk from the spread of viruses, but so far, none have been described in BSFs. To fill this knowledge gap, a bioinformatic approach was undertaken to discover viruses specifically associated with BSFs. First, BSF genomes were screened for the presence of endogenous viral elements (EVEs). This led to the discovery and mapping of seven orthologous EVEs integrated into three BSF genomes originating from five viral families. Secondly, a virus discovery pipeline was used to screen BSF transcriptomes. This led to detecting a new exogenous totivirus that we named hermetia illucens totivirus 1 (HiTV1). Phylogenetic analyses showed this virus belongs to a clade of insect-specific totiviruses and is closely related to the largest EVE located on chromosome 1 of the BSF genome. Lastly, this EVE was found to express a small transcript in some BSFs infected by HiTV1. Altogether, this data mining study showed that far from being unscathed from viruses, BSFs bear traces of past interactions with several viral families and of present interactions with the exogenous HiTV1.
Insights
Black soldier flies (BSFs) harbor viral genetic remnants and a newly identified totivirus (HiTV1). This discovery highlights the susceptibility of BSFs to viral infections, impacting their use in food, feed, and waste bioconversion industries.
Area of Science:
- Virology
- Entomology
- Bioinformatics
Background:
- Black soldier flies (BSFs, *Hermetia illucens*) are increasingly important for insect-based food, feed, and waste bioconversion.
- Mass-rearing facilities for insects face risks from viral pathogen spread.
- No viruses have been previously described in BSFs, creating a knowledge gap.
Purpose of the Study:
- To identify viruses associated with BSFs using a bioinformatic approach.
- To investigate past and present viral interactions within BSF populations.
Main Methods:
- Screening of BSF genomes for endogenous viral elements (EVEs).
- Utilizing a virus discovery pipeline on BSF transcriptomes.
- Phylogenetic analysis of identified viral sequences.
Main Results:
- Discovery and mapping of seven orthologous EVEs from five viral families in BSF genomes.
- Detection of a novel exogenous totivirus, hermetia illucens totivirus 1 (HiTV1).
- HiTV1 is phylogenetically related to a large EVE found in the BSF genome, which expresses a transcript during HiTV1 infection.
Conclusions:
- BSFs are not virus-free and show evidence of past viral interactions through EVEs.
- A new exogenous totivirus (HiTV1) has been identified in BSFs.
- The study reveals a complex relationship between BSFs and viruses, including potential co-evolutionary links between EVEs and exogenous viruses.
