ARS | Publication request: Transient gut retention and persistence of Salmonella through metamorphosis in the lesser mealworm, Alphitobius diaperinus (Coleoptera: Tenebrionidae)

Submitted to: Journal of Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 17, 2012
Publication Date: May 1, 2012
Citation: Crippen, T.L., Zheng, L., Sheffield, C.L., Tomberlin, J.K., Beier, R.C., Yu, Z. 2012. Transient gut retention and persistence of Salmonella through metamorphosis in the lesser mealworm, Alphitobius diaperinus (Coleoptera: Tenebrionidae). Journal of Applied Microbiology. 112:920-926.

Interpretive Summary: All of the sources of foodborne pathogens within the poultry production process are not known. Without this knowledge it is difficult to design effective biosecurity protocols to reduce the transfer of pathogenic bacteria between animals, humans, and the environment. This study was undertaken to determine: 1) how long the lesser mealworm, a common pest in poultry production facilities, can continue to contaminate its surrounding environment if fed one meal containing Salmonella, and 2) if Salmonella fed to the larval stage of the insect is present after transformation into an adult beetle. A tagged Salmonella enterica was used to track bacterial movement. Exposed adults and larvae defecated Salmonella for an average of 8 days (ranging from 6 to 12 days) after a single 2-hour exposure. Nineteen percent of the larvae retained the Salmonella through development into an adult. Poultry broiler operations commonly reutilize the litter on which these insect live for consecutive flocks of birds. A rotation period between flocks normally varies from 1-2 weeks. The lesser mealworm survives between flock rotations, and this study demonstrated that the Salmonella they carry can survive with them.

Technical Abstract: his study was undertaken to determine the retention of Salmonella through Alphitobius diaperinus metamorphosis and the contribution of defecation to external contamination. Adults and larvae were exposed to a tagged Salmonella enterica and evaluated for external elimination. Each day for three weeks a sterile filter collected the frass (feces) from a restrained insect onto a fresh, sterile collection filter for analysis. Exposed larvae in a closed container were followed through pupation and newly emerged adults were examined for their retention of marker bacteria. Exposed adults and larvae produced Salmonella positive frass for an average of 8 days, ranging from 6 to 11 days and 6 to 12 days, respectively. Nineteen percent of the larvae carried Salmonella through metamorphosis and eclosion, with 5% of the pupal exuviae being positive as well. All sources, including reservoir populations, of foodborne pathogens within the poultry production process are not known. This diminishes the ability of producers to mitigate the transfer of pathogens between animals, humans, and the environment. Poultry management standards accept the reutilization of litter. Alphitobius diaperinus survive between flock rotations on the reutilized litter, and it was demonstrated in this study that the Salmonella they carry can survive with them.