Sequencing to identify pathogens in insects farmed for food and feed

Authors: LEIERER, DEWEY - Kansas State University; Olmstead, Morgan; Oppert, Brenda

Submitted to: Frontiers in Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/4/2023
Publication Date: 1/30/2023
Citation: Leierer, D., Olmstead, M.L., Oppert, B.S. 2023. Sequencing to identify pathogens in insects farmed for food and feed. Frontiers in Insect Science. https://doi.org/10.3389/finsc.2023.1059046.
DOI: https://doi.org/10.3389/finsc.2023.1059046

Interpretive Summary: Insects are being farmed to meet the growing demand for sustainable protein for animal and human feed. However, disease outbreaks in large insect farms can cause rapid losses of insect colonies. In many cases, the cause of the collapse is difficult to determine, and it is important to develop methods to rapidly identify potential pathogens to contain outbreaks We provide a case study of a laboratory mealworm colony that suffered a collapse. Sequencing was used to compare the microbial profiles of collapsed and healthy insects to identify potential pathogens. The collapsed colony had higher abundances of bacteria associated with infections, and also exhibited a loss of microbial diversity when compared to the healthy colony. These data suggest that microbial flora in insects is important in maintaining healthy colonies, and stress can lead to an imbalance of bacteria and disease. The data will contribute to understanding how to maintain healthy colonies of farmed insects.

Technical Abstract: The farmed insect industry is increasing in number and size to meet the demand for sustainably-produced protein.  Larger insect farms are prone to losses due to pathogens, and more information is needed regarding the health of insects reared for food and feed.  In this study, high throughput sequencing was used to identify potential pathogens in a colony of Tenebrio molitor (yellow mealworm, Coleoptera: Tenebrionidae) that exhibited increased mortality in immature stages with eventual colony collapse.  Sequences also were obtained from a healthy new colony of T. molitor, as well as a recovered individual from the collapsed colony. Screening of sequences obtained from the colonies and their rearing diet indicated that the collapsed colony had low diversity in microbial taxa, with predominantly sequences from the families Staphylococcaeceae and Streptococcaceae constituting from 76 to 93% of the total microbial reads.  Conversely, in the new colony and their rearing diet, microbial sequences were from more than 15 different taxa, with Lactobacilleceae the most prevalent but only 21% of the total microbial reads.  Sequences from the recovered individual reflected an intermediate microbial flora profile between the diseased collapsed and new colonies.  These findings have implications for insects reared in confined environments and provide a method to screen insect health in healthy and potentially diseased individuals.