Transmission and Retention of Salmonella enterica by Phytophagous Hemipteran Insects

Abstract

ABSTRACTSeveral pest insects of human and livestock habitations are known as vectors ofSalmonella enterica; however, the role of plant-feeding insects as vectors ofS. entericato agricultural crops remains unexamined. Using a hemipteran insect pest-lettuce system, we investigated the potential for transmission and retention ofS. enterica. Specifically,Macrosteles quadrilineatusandMyzus persicaeinsects were fedS. enterica-inoculated lettuce leaf discs or artificial liquid diets confined in Parafilm sachets to allow physical contact or exclusively oral ingestion of the pathogen, respectively. After a 24-h acquisition access period, insects were moved onto two consecutive noninoculated leaf discs or liquid diets and allowed a 24-h inoculation access period on each of the two discs or sachets. Similar proportions of individuals from both species ingestedS. entericaafter a 24-h acquisition access period from inoculated leaf discs, but a significantly higher proportion ofM. quadrilineatusretained the pathogen internally after a 48-h inoculation access period.S. entericawas also recovered from the honeydew of both species. After a 48-h inoculation access period, bacteria were recovered from a significantly higher proportion of honeydew samples fromM. quadrilineatusthan fromM. persicaeinsects. The recovery ofS. entericafrom leaf discs and liquid diets postfeeding demonstrated that both species of insects were capable of transmitting the bacteria in ways that are not limited to mechanical transmission. Overall, these results suggest that phytophagous insects may serve as potential vectors ofS. entericain association with plants.