Adult Alphitobius diaperinus microbial community during broiler production and in spent litter after stockpiling

Authors: Crippen, Tawni - Tc; SINGH, BANESHWAR - Virginia Commonwealth University; Anderson, Robin; SHEFFIELD, CYNTHIA - Retired ARS Employee

Submitted to: Microorganisms
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2022
Publication Date: 1/14/2022
Citation: Crippen, T.L., Singh, B., Anderson, R.C., Sheffield, C.L. 2022. Adult Alphitobius diaperinus microbial community during broiler production and in spent litter after stockpiling. Microorganisms. 10(1). Article 175. https://doi.org/10.3390/microorganisms10010175.
DOI: https://doi.org/10.3390/microorganisms10010175

Interpretive Summary: With the increasing demand for chicken meat, a thorough evaluation of the bacterial community within the grow-out houses and litter deposit sites is crucial for the well-being of both the animals and the environment. However, not much is known about the microbial community harbored by the lesser mealworm bettle, which lives within the litter of most broiler houses and is in close contact with the birds. This work evaluates the bacterial community of these beetles over 11 flock rotations, a partial and a total cleanout of the litter, and the subsequent use of the litter as fertilizer on pastureland. The beetles maintained a relatively stable bacterial community, despite time and cleanout practices within the house, establishing them as a long-term reservoir of microbes in this system. The beetles were also transferred with the litter when it was cleaned out and stockpiled onto pastureland for use as fertilizer. The waste matter produced by the beetles has great benefits to plant growth as a fertilizer. In the outdoor environment, the bacterial community varies over time and with environmental changes. The potential of the beetles for moving microbial organisms into the environment is high and should be further assessed to maintain a proper balance between the use of animal wastes and environmental health. This is to assure that the risk of relocating foodborne pathogens can be minimized, and the contribution of mineral production when the litter is used as a fertilizer can be maximized.

Technical Abstract: The facilities used to raise broiler chickens are often infested with litter beetles (lesser mealworm, Alphitobius diaperinus). These beetles have been studied for their carriage of pathogenic microbes, however a more comprehensive microbiome study on these arthropods is lacking. This study investigates the microbial community of lesser mealworm in a longitudinal study throughout 2.5 yrs. of poultry production and after the spent litter, containing the mealworms, was piled in pastureland for use as fertilizer. The mean, most abundant phyla harbored by the beetles in-house were the Proteobacteria (39.8%), the Firmicutes (30.8 %), the Actinobacteria (21.1%), the Tenericutes (5.1 %), the Bacteroidetes (1.6%), and unclassified bacteria (1.5%). Indicator species analysis identified 9 indicators that had notably increased in-house during different flock rotations. In general, the microbial profile of the beetles in the house remained relatively stable despite litter clean-out management procedures, with a modest decrease in Firmicutes and an increase in Proteobacteria over successive flock rotations. The beetles were removed from the controlled conditions of the poultry house and inadvertently relocated within the spent litter to pastureland. They were found at least 19 weeks later and transported a substantial microbial diversity with them into the open environment. Over time in the pastureland, their microbial profile underwent a large decrease in the mean percent abundance of Firmicutes (20.5%). Ten indicator species were identified that had a higher percent abundance in the early weeks (0-5) and 9 indicators in the later weeks (7-19). Therefore, considering the LM’s ability to harbor a longstanding microbial community despite disruptions to their in-house environment and their ability to survive long-term within the spent litter. Their potential of transferring microbial organisms into the environment should be assessed to both reduce the risk of transferring foodborne pathogens, as well as enhance their contribution when the litter is used as a fertilizer.