Microbial Dynamics During Industrial Rearing And Processing Of Insects

In Western countries, the commercial exploitation of insects within the food industry is fast growing, as well as their use as a source of biochemicals or as a waste converter. In other countries, a long tradition of entomophagy, i.e. the consumption of insects by humans, already exists. Typically, insects are caught in the wild, but as this practice may affect biodiversity and as the safety and nutritional quality of wild-harvested insects is unknown, efforts are made to rear these species on defined substrates. Whatever the motivation to set up an insect farming system, questions arise on the microbiological quality of the insects during rearing and subsequent processing.

For traditional farm animals, such as poultry, pigs, and ruminants, the impact of the gut microbiota on zootechnical performance and its management towards eubiosis has been studied for decades. In insects living in nature, a plethora of symbionts and their interaction mechanisms with the host has also been described. When rearing insects at an industrial scale, however, their microbiological environment likely differs from that in nature, and other insect-microbiome interactions may exist. Limited research in cooperation with insect producers has shown that food pathogens such as Bacillus cereus and Salmonella can be part of the gut microbiome. Yet the impact of the rearing conditions and post-harvest processing parameters on the survival of pathogens in the end product, e.g. the whole insect, an insect powder or paste, have hardly been investigated. Since the effect of microbial decontamination strategies not only depends on the conditions applied but also on the matrix, their effect on insects cannot simply be extrapolated from other matrices.

In addition, rearers are confronted with insect pathogens that affect production yield. These entomopathogens can be viruses, bacteria, fungi, and nematodes. Some species are specialists and will only attack one or few species, but they can anyway be disastrous for the production. This is, for example, the case for the virus infecting crickets. Other species, like certain Pseudomonas spp, are generalists and can attack a range of insect species. Knowledge about the diagnosis of insect diseases and their management (or prevention) is essential. Also relevant to know is to which extent some opportunistic microorganisms can act as insect pathogens and food contaminants at the same time.

Insight in the microbial dynamics during production and processing of insects at industrial scale can contribute to ultimately manage the gut microbiota and/or the immune system, so that (entomo)pathogen colonization can be prevented or reduced. On the longer term, microbiological criteria can be established. Also, side streams now prohibited as substrate (due to lack of research data) may eventually be authorized, hence further increasing the sustainability of industrial insects.

In this Research Topic, we welcome Original Research articles and (Mini) Reviews dedicated to the characterization and control of the microbiota of industrially relevant insects during rearing and/or processing into feed, pet food or food using traditional or novel technologies and investigated under conditions that are relevant to the industry.

The Topic Editors would like to acknowledge Dr. Dries Vandeweyer and Dr. Jeroen De Smet for their contribution in designing and organizing this editorial project.