Active and Covert Infections of Cricket Iridovirus and Acheta domesticus Densovirus in Reared Gryllodes sigillatus Crickets

Abstract

Interest in developing food, feed, and other useful products from farmed insects has gained remarkable momentum in the past decade. Crickets are an especially popular group of farmed insects due to their nutritional quality, ease of rearing, and utility. However, production of crickets as an emerging commodity has been severely impacted by entomopathogenic infections, about which we know little. Here, we identified and characterized an unknown entomopathogen causing mass mortality in a lab-reared population of Gryllodes sigillatus crickets, a species used as an alternative to the popular Acheta domesticus due to its claimed tolerance to prevalent entomopathogenic viruses. Microdissection of sick and healthy crickets coupled with metagenomics-based identification and real-time qPCR viral quantification indicated high levels of cricket iridovirus (CrIV) in a symptomatic population, and evidence of covert CrIV infections in a healthy population. Our study also identified covert infections of Acheta domesticus densovirus (AdDNV) in both populations of G. sigillatus. These results add to the foundational research needed to better understand the pathology of mass-reared insects and ultimately develop the prevention, mitigation, and intervention strategies needed for economical production of insects as a commodity.

Identification by cryoEM of a densovirus causing mass mortality in mass-reared larval darkling beetles (Zophobas morio)

“…It is unknown whether ZmBWV can be carried by asymptomatic beetles. There is some precedent for asymptomatic carriage of DVs [24]. Therefore, when bringing new beetles into a breeding colony, avoiding overtly-symptomatic individuals might not be sufficient.…”

“…DVs, in general, display high virulence and pathogenicity, which has been shown to affect insects in their larval stage [2][3][4][5][6][7][8], crustaceans [9][10][11][12][13][14], mollusks [15,16] as well as echinoderms [17][18][19]. Mass-reared arthropods are especially in danger of DV infection [20][21][22][23][24]. The superworm (Zophobas morio), a species of darkling beetle, is one such arthropod species; its larvae are a staple item on the diet of captive reptiles, birds and amphibians worldwide, and it is under investigation as a next-generation animal protein source [25].…”

Structural and molecular biology of Acheta domesticus segmented densovirus, the first parvovirus to harbor a bipartite genome

“…Acquiring VP-ORF3 could have extended its original dipteran host spectrum to orthopterans, especially when considering the narrow host spectrum of AdSDV. While AdDV causes subclinical infection in other commonly reared orthopteran species [53], AdSDV is host-specific to A. domesticus .…”

First Evidence of Past and Present Interactions between Viruses and the Black Soldier Fly, Hermetia illucens

“…The size of the viral sequence hits ranged between 148 and 3750 nucleotides. All three BSF genome assemblies received hits related to Partitiviridae (5), Parvoviridae (7), Totiviridae (10), and Totiviridae-like (3) viruses, while a hit related to either Rhabdoviridae or Xinmoviridae was found in BGA2 and BGA3 respectively. The pipeline also identified six sequences of porcine reproductive and respiratory syndrome virus (Arteriviridae) in the data from BGA2, but these were discarded because they were on contigs that all lacked flanking insect sequences and therefore likely resulted from sequence contamination.…”

“…Although well established in Asia, upscaling cricket farming in North America and Europe has been hampered by outbreaks of cricketinfecting viruses belonging to the Parvoviridae, Iflaviridae, and Iridoviridae families that can cause a high level of mortalities and economic losses [2][3][4][5][6]. Besides recent virus discoveries in crickets, there is also evidence of a wide variation in viral prevalence among cricket populations [3][4][5]7]. Similarly, in honey bees, Apis mellifera, viral pathogens affect both wild hives and apiaries globally [8].…”