Management practices affecting lesser mealworm larvae (Alphitobius diaperinus) associated microbial community in a broiler house and after relocating with the litter into pastureland

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

Submitted to: Frontiers in Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/8/2022
Publication Date: 7/1/2022
Citation: Crippen, T.L., Singh, B., Anderson, R.C., Sheffield, C.L. 2022. Management practices affecting lesser mealworm larvae (Alphitobius diaperinus) associated microbial community in a broiler house and after relocating with the litter into pastureland. Frontiers in Microbiology. 13. Article 875930. https://doi.org/10.3389/fmicb.2022.875930.
DOI: https://doi.org/10.3389/fmicb.2022.875930

Interpretive Summary: With the increasing human population, poultry production is growing and a thorough evaluation of the bacterial community within broiler grow-out houses and litter deposit sites is crucial for animal and environmental well-being. Many poultry houses are infested with the lesser mealworm beetle that is in close contact with the poultry. This work evaluates the bacterial community of the larval stage of the beetle. The study was conducted over a 2.5 year period including a partial and a total cleanout of the litter, and the subsequent use of the litter as fertilizer on pastureland. The larvae maintained a relatively stable bacterial community despite the time and the cleanout practices within the house, revealing them as long-term reservoirs of many microbe species in the poultry houses. When the litter was cleaned out, the larvae were transferred within the litter as it was stockpiled onto pastureland for use as fertilizer. In the pastureland, the bacterial community environment fluctuated over time. The waste matter produced by the larvae contains minerals generated by their microbes that have excellent benefits to plant growth as a fertilizer. The potential of the larvae for moving microbial organisms into the environment is high and needs further assessment to minimize the risk of relocating foodborne pathogens and maximizing their contribution for mineral production when the litter is used as a fertilizer.

Technical Abstract: Lesser mealworms are often found infesting production houses used to raise broiler chickens. Previous studies have investigated pathogenic microorganisms associated with the larvae, but a more thorough study relating total microbiome changes due to management procedures and flock rotations were needed. Additionally, there is a question of what microbiota are transferred into the environment when the litter, in which larvae reside, is piled in pastureland for use as fertilizer and where interactions with the soil and other fauna can occur. This study chronicled, by the 16S rRNA sequencing, the bacterial community profile of larvae in a broiler grow-out house synchronizing to when birds were added to and removed from the house over 2.5 years. The profile was found to be relatively constant despite 11 flock rotations and management disruptions, specifically litter cleanout procedures and the addition of new birds or bedding. In contrast, once removed from the controlled broiler house environment and placed into open pastureland, the substantial microbial diversity brought with the larvae showed greater fluctuation in structure with environmental conditions, one of which was rainfall. Surprisingly, these larvae survived at least 19 weeks, so the potential for moving larval-associated microbes into the environment needs further assessment to minimize the risk of relocating foodborne pathogens and also to assess those bacteria-generating metabolites that have benefits to plant growth when using the litter as a fertilizer. The characterization of their microbiome is the first step to investigating the influences of their microbes on the manmade and environmental ecosystems.