The use of insects as a bioassay for Penaeus merguiensis densovirus (PmergDNV)

Safety of Acheta domesticus powder as a Novel food pursuant to Regulation (EU) 2015/2283

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on Acheta (A.) domesticus powder as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The main components of the NF are protein, fat and dietary fibre (chitin). The Panel notes that the concentration of contaminants in the NF depends on the occurrence levels of these substances in the insect feed. The Panel further notes that there are no safety concerns regarding the stability of the NF if the NF complies with the proposed specification limits during its entire shelf-life. The NF has a high protein content, although the true protein content is overestimated when using the nitrogen-to-protein conversion factor of 6.25 due to the presence of non-protein nitrogen from chitin. The applicant proposed to use the NF as food ingredient in a number of food products. The target population proposed by the applicant is the general population. Considering the composition of the NF and the proposed conditions of use, the consumption of the NF is not nutritionally disadvantageous. The panel notes that no safety concerns arise from the toxicological information of A. domesticus. The panel considers that the consumption of the NF might trigger primary sensitisation to A. domesticus proteins and may cause allergic reactions in subjects allergic to crustaceans, mites and molluscs. Additionally, allergens from the feed may end up in the NF. The panel concludes that the NF is safe under the proposed uses and use levels.

Safety of partially defatted house cricket (Acheta domesticus) powder as a novel food pursuant to Regulation (EU) 2015/2283

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on defatted house cricket (Acheta domesticus) powder as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The NF is proposed as dry powder. The main components of the NF are protein, fat and fibre (chitin). The Panel notes that the concentration of contaminants in the NF depends on the occurrence levels of these substances in the insect feed. The Panel further notes that there are no safety concerns regarding the stability of the NF if the NF complies with the proposed specification limits during its entire shelf life. The NF has a high protein content, although the true protein levels are overestimated when using the nitrogen‐to‐protein conversion factor of 6.25 due to the presence of non‐protein nitrogen from chitin. The applicant proposed to use the NF as food ingredient in a number of food products. The target population proposed by the applicant is the general population. The Panel notes that, considering the composition of the NF and the proposed conditions of use, the consumption of the NF is not nutritionally disadvantageous. The Panel notes that no genotoxicity and no subchronic toxicity studies with the NF were provided by the applicant. Considering that no safety concerns arise from the history of use of the source of the NF (A. domesticus), and the limited difference between the whole insect and the partially defatted NF, the Panel identified no other safety concerns than allergenicity. The Panel considers that the consumption of the NF might trigger primary sensitisation to A. domesticus proteins and may cause allergic reactions in subjects allergic to crustaceans, mites and molluscs. Additionally, allergens from the feed may end up in the NF. That aside, the Panel concludes that the NF is safe under the proposed uses and use levels.

A Systematic Review on Viruses in Mass-Reared Edible Insect Species

Edible insects are expected to become an important nutrient source for animals and humans in the Western world in the near future. Only a few studies on viruses in edible insects with potential for industrial rearing have been published and concern only some edible insect species. Viral pathogens that can infect insects could be non-pathogenic, or pathogenic to the insects themselves, or to humans and animals. The objective of this systematic review is to provide an overview of the viruses detected in edible insects currently considered for use in food and/or feed in the European Union or appropriate for mass rearing, and to collect information on clinical symptoms in insects and on the vector role of insects themselves. Many different virus species have been detected in edible insect species showing promise for mass production systems. These viruses could be a risk for mass insect rearing systems causing acute high mortality, a drastic decline in growth in juvenile stages and in the reproductive performance of adults. Furthermore, some viruses could pose a risk to human and animal health where insects are used for food and feed.

Safety of frozen and dried formulations from whole house crickets (Acheta domesticus) as a Novel food pursuant to Regulation (EU) 2015/2283

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Food and Food Allergens (NDA) was asked to deliver an opinion on the safety of frozen and dried formulations from house crickets (Acheta domesticus) as a novel food pursuant to Regulation (EU) 2015/2283. The NF is proposed in three formulations: (i) frozen, (ii) dried, (iii) ground. The main components of the NF are protein, fat and fibre (chitin) in the dried form of the NF, and water, protein, fat and fibre (chitin) in the frozen form of the NF. The Panel notes that the concentrations of contaminants in the NF depend on the occurrence levels of these substances in the insect feed. The Panel further notes that there are no safety concerns regarding the stability of the NF if the NF complies with the proposed specification limits during its entire shelf-life. The NF has a high-protein content, although the true protein levels in the NF are overestimated when using the nitrogen-to-protein conversion factor of 6.25, due to the presence of non-protein nitrogen from chitin. The applicant proposed to use the NF in the form of a snack, and as a food ingredient in a number of food products. The target population proposed by the applicant is the general population. The Panel notes that, considering the composition of the NF and the proposed conditions of use, the consumption of the NF is not nutritionally disadvantageous. The Panel notes that no genotoxicity and no subchronic toxicity studies with the NF were provided by the applicant. Considering that no safety concerns arise from the history of use of A. domesticus or from the compositional data of the NF, the Panel identified no other safety concerns than allergenicity. The Panel considers that the consumption of the NF might trigger primary sensitisation to A. domesticus proteins and may cause allergic reactions in subjects allergic to crustaceans, mites and molluscs. Additionally, allergens from the feed may end up in the NF. The Panel concludes that the NF is safe under the proposed uses and use levels.

Diversity of single-stranded DNA containing viruses in shrimp

Over the past four decades, shrimp aquaculture has turned into a major industry providing jobs for millions of people worldwide especially in countries with large coastal boundaries. While the shrimp industry continues to expand, the sustainability of shrimp aquaculture has been threatened by the emergence of diseases. Diseases caused by single-stranded DNA containing viruses, such as infectious hypodermal and hematopoietic necrosis virus (IHHNV) and hepatopancreatic parvovirus (HPV), have caused immense losses in shrimp aquaculture since the early 1980s. In fact, the disease outbreak in the blue shrimp (Penaeus stylirostris) caused by IHHNV in early 1980s ultimately led to the captive breeding program in shrimp being shifted from P. stylirostris to the white shrimp (Penaeus vannamei), and today P. vannamei is the preferred cultured shrimp species globally. To date, four single-stranded DNA viruses are known to affect shrimp; these include IHHNV, HPV, spawner-isolated mortality virus (SMV) and lymphoidal parvo-like virus (LPV). Due to the economic losses caused by IHHNV and HPV, most studies have focused on these two viruses, and only IHHNV is included in the OIE list of Crustacean Diseases. Hence this review will focus on IHHNV and HPV. IHHNV and HPV virions are icosahedral in morphology measuring 20-22 nm in size and contain a single-stranded DNA (ssDNA) of 4-6 kb in size. Both IHHNV and HPV are classified into the sub-order Brevidensoviruses, family Densovirinae. The genome architecture of both viruses are quite similar as they contain two completely (as in IHHNV) or partially overlapping (as in HPV) non-structural and one structural gene. Histopathology and polymerase chain reaction (PCR)-based methods are available for both viruses. Currently, there is no anti-viral therapy for any viral diseases in shrimp. Therefore, biosecurity and the use of genetically resistant lines remains as the corner stone in the management of viral diseases. In recent years, gene silencing using the RNA interference (RNAi) approach has been reported for both IHHNV and HPV via injection. However, the delivery of RNAi molecules via oral route remains a challenge, and the utility of RNAi-based therapy has yet to be materialized in shrimp aquaculture.

Biology, genome organization, and evolution of parvoviruses in marine shrimp

As shrimp aquaculture has evolved from a subsistent farming activity to an economically important global industry, viral diseases have also become a serious threat to the sustainable growth and productivity of this industry. Parvoviruses represent an economically important group of viruses that has greatly affected shrimp aquaculture. In the early 1980s, an outbreak of a shrimp parvovirus, infectious hypodermal and hematopoietic necrosis virus (IHHNV), led to the collapse of penaeid shrimp farming in the Americas. Since then, considerable progress has been made in characterizing the parvoviruses of shrimp and developing diagnostic methods aimed to preventing the spread of diseases caused by these viruses. To date, four parvoviruses are known that infect shrimp; these include IHHNV, hepatopancreatic parvovirus (HPV), spawner-isolated mortality virus (SMV), and lymphoid organ parvo-like virus. Due to the economic repercussions that IHHNV and HPV outbreaks have caused to shrimp farming over the years, studies have been focused mostly on these two pathogens, while information on SMV and LPV remains limited. IHHNV was the first shrimp virus to be sequenced and the first for which highly sensitive diagnostic methods were developed. IHHNV-resistant lines of shrimp were also developed to mitigate the losses caused by this virus. While the losses due to IHHNV have been largely contained in recent years, reports of HPV-induced mortalities in larval stages in hatchery and losses due to reduced growth have increased. This review presents a comprehensive account of the history and current knowledge on the biology, diagnostics methods, genomic features, mechanisms of evolution, and management strategies of shrimp parvoviruses. We also highlighted areas where research efforts should be focused in order to gain further insight on the mechanisms of parvoviral pathogenicity in shrimp that will help to prevent future losses caused by these viruses.

Suppression of Penaeus merguiensis densovirus following oral delivery of live bacteria expressing dsRNA in the house cricket (Acheta domesticus) model

Penaeus merguiensis densovirus (PmergDNV) is a serious pathogen of the banana prawn, Penaeus merguiensis leading to at least 28% production loss due to reduced growth rates and mortality of juveniles. In the present study, we reduced PmergDNV titres and subsequent mortality by feeding Acheta domesticus (previously determined as an appropriate animal model for P. merguiensis) with dsRNA specific to the capsid protein by mixing it into their food. Feeding A. domesticus with PmergDNV-specific dsRNA in advance of viral challenge increased their longevity, decreased mortality by 84.4% and reduced viral loads 24-fold below the threshold level required for mortality. Mortalities and viral loads were significantly (both P < 0.001) lower in treatments challenged with PmergDNV following exposure to bacterially expressed PmergDNV-dsRNA. This is the first study to demonstrate gene silencing via RNAi against PmergDNV in vivo through oral administration of live bacteria expressing dsRNA in a model system.

Molecular Biology and Epidemiology of Hepatopancreatic parvovirus of Penaeid Shrimp

Hepatopancreatic parvovirus (HPV) is one of the major shrimp parvovirus which is known to cause slow growth in penaeid shrimps. HPV has been found in wild and cultured penaeid shrimps throughout the world and there is high genetic variation among the different geographic isolates/host species. Given its high prevalence, wide distribution and ability to cause considerable economic loss in shrimp aquaculture industry, HPV deserves more attention than it has received. Till date, a total of four complete genome sequences of HPV have been reported in addition to a large number of partial sequences. HPV infection is seldom observed alone in epizootics and has occurred in multiple infections with other more pathogenic viruses and in most cases, heavy infections result in no visible inflammatory response. A great deal of information has accumulated in recent years on the clinical signs, geographical distribution, transmission and genetic diversity of HPV infection in shrimp aquaculture. However, the mechanism by which HPV enters the shrimp tissues and pathogenesis of virus is still unknown. To date, no effective prophylactic measures are available to reduce the infection in shrimps. To control and prevent HPV infection, considerable research efforts are on. This review provides information on current knowledge on HPV infection in penaeid shrimp aquaculture.

RNA interference with special reference to combating viruses of crustacea

RNA interference has evolved from being a nuisance biological phenomenon to a valuable research tool to determine gene function and as a therapeutic agent. Since pioneering observations regarding RNA interference were first reported in the 1990s from the nematode worm, plants and Drosophila, the RNAi phenomenon has since been reported in all eukaryotic organisms investigated from protozoans, plants, arthropods, fish and mammals. The design of RNAi therapeutics has progressed rapidly to designing dsRNA that can specifically and effectively silence disease related genes. Such technology has demonstrated the effective use of short interfering as therapeutics. In the absence of a B cell lineage in arthropods, and hence no long term vaccination strategy being available, the introduction of using RNA interference in crustacea may serve as an effective control and preventative measure for viral diseases for application in aquaculture.