Evaluation of Salmonella movement through the gut of the lesser mealworm, Alphitobius diaperinus (Coleoptera: Tenebrionidae).
OBJECTIVE
The lesser mealworm, Alphitobius diaperinus is an important poultry pest prevalent during production that is capable of vectoring pathogens. This study was undertaken to determine the gut transit time of Salmonella for biosecurity risk analysis of pathogen dispersal into the environment.


METHODS
Adult and larval A. diaperinus were exposed to two concentrations of a fluorescently labeled Salmonella enterica for 15, 30, and 60 min time periods then externally disinfected to evaluate internal transfer of Salmonella. The insects were monitored every 30 min over 4 h and evacuated frass (feces) processed for the marker Salmonella. The minimum time monitored was 45 min (15 exposure+30 min time point), and the maximum was 5 h (60 exposure+4 h time point).


RESULTS
Adults treated with 10(6) or 10(8) colony-forming units (cfu)/mL, which produced Salmonella positive frass within the 5 h experimental time, displayed a mean gut transit time of 144.4 min (range 90-270 min) and 186.3 min (range 120-300 min), respectively. Larvae treated with 10(6) or 10(8) cfu/mL displayed a mean gut transit time of 172.5 min (range 120-300 min) and 131.7 min (range 60-300 min), respectively.


CONCLUSIONS
Understanding the sources and contribution of reservoir populations of pathogens in poultry production operations is important for development of biosecurity measures to mitigate their transfer. A. diaperinus are prevalent in production operations and difficult to suppress. Management standards accept the reutilization of litter in which insects survive between flock rotations. Removing litter and spreading it onto nearby fields results in the inadvertent dispersal of beetles. Few studies demonstrating the specific bacterial dispersal capacities of these insects have been performed. This study determined that Salmonella acquired internally, commonly transits the gut, allowed the insect to disperse viable pathogenic bacteria within 2-3 h.
State Key Laboratory of Agricultural Microbiology, National Engineering Research Center of Microbial Pesticides, Huazhong Agricultural University, Wuhan, China.
Longyu
L
Zheng
Tawni L
TL
Crippen
Cynthia L
CL
Sheffield
Toni L
TL
Poole
Ziniu
Z
Yu
Jeffrey K
JK
Tomberlin
D000818:Animals; D001517:Coleoptera / Q000382:microbiology*; D015169:Colony Count, Microbial; D004203:Disinfection; D041981:Gastrointestinal Tract / Q000382:microbiology* / Q000502:physiology; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007303:Insect Vectors / Q000382:microbiology* / Q000502:physiology; D007814:Larva / Q000382:microbiology / Q000502:physiology; D050296:Microbial Viability; D008856:Microscopy, Fluorescence; D019779:Salmonella enterica / Q000378:metabolism / Q000472:pathogenicity / Q000502:physiology*; D013997:Time Factors
D049452:Green Fluorescent Proteins