A systematic review of experimental studies on Salmonella persistence in insects

The consumption of insects as food and feed has been recently suggested as a possible alternative to the rising global food need, thus it is crucial to monitor any potential food safety hazards in the insect supply chain. The aims of this systematic review were to collect, select, and evaluate studies investigating the persistence of Salmonella in insects. We searched PUBMED, EMBASE, WEB of Science Core Collection, and Food Science and Technology Abstracts. In total, 36 papers investigating the persistence of Salmonella in insects (both holometabolous and heterometabolous) were included after screening. Regarding complete metamorphosis insects, the longest Salmonella persistence was reported in Phormia regina, in which the pathogen persisted for 29 days at 5 °C. Similarly, Salmonella persisted in the feces of Alphitobius diaperinus for 28 days. The incomplete metamorphosis insect showing the longest Salmonella persistence (>10 months) was Blatella germanica. Periplaneta americana excreted Salmonella via feces for 44 days until all the insects were dead. The retrieved data on the persistence of Salmonella can be useful for further analysis by risk assessors and decision-makers involved in the safety of insect-based food, contributing to defining the sanitary requirements and risk mitigation measures along the supply chain. The review protocol is registered in PROSPERO database (CRD42022329213).

A systematic review on the occurrence of Salmonella in farmed Tenebrio molitor and Acheta domesticus or their derived products

Insects represent a sustainable and protein-rich food source. This new supply chain requires the study and monitoring of pathogens' presence and impact, as for other farmed animals. Among pathogens, Salmonella is of interest due to the well-established possibility for insects to harbor it. Since Acheta domesticus (cricket) and Tenebrio molitor (mealworm) are the most sold and farmed insect species, the present systematic review aimed to collect, select, and evaluate, in the available scientific literature, studies investigating the occurrence of Salmonella in these species sampled. All available studies published in peer-reviewed journals in English, French, Italian, Portuguese, German, and Spanish were considered. No time limits were imposed. We searched PUBMED, EMBASE, WEB of Science Core Collection, and Food Science and Technology Abstracts. The first date searched was May 10th, 2022; an update of the search was conducted on May 5th, 2023. The data synthesis was presented in tables reporting the number of positives on the number of total analyzed samples with other relevant characteristics of the study. The quality assessment was carried out considering relevant aspects for sampling and the method of analysis for Salmonella detection. At the end of the screening process, 10 and nine studies conducted on crickets and mealworms, respectively, were included for data extraction. The S. serovar Wandsworth and S. serovar Stanley were isolated only in one sample of ready-to-eat crickets. A second study detected OTUs related to S. enterica in cricket and mealworm powders. No studies detected Salmonella in mealworms according to cultural methods. The limitations of the present review are that few studies were retrieved and that included studies had important limitations in terms of study design as sampling was mostly based on convenience and not on a sound statistical basis. The present systematic review underlines the need to obtain reliable data about Salmonella presence in insects considering the growing market and the scaling up of existing farms. This research was funded by the Italian Ministry of Health - Ricerca Corrente IZSVe 03/21. The review protocol was published on the Systematic Reviews for Animals and Food (SYREAF) Web site (https://syreaf.org/protocols/).