Interaction of Phytophagous Insects with Salmonella enterica on Plants and Enhanced Persistence of the Pathogen with Macrosteles quadrilineatus Infestation or Frankliniella occidentalis Feeding

Recently, most foodborne illness outbreaks of salmonellosis have been caused by consumption of contaminated fresh produce. Yet, the mechanisms that allow the human pathogen  Salmonella enterica  to contaminate and grow in plant environments remain poorly described. We examined the effect of feeding by phytophagous insects on survival of  S. enterica  on lettuce. Larger  S. enterica  populations were found on leaves infested with  Macrosteles quadrilineatus . In contrast, pathogen populations among plants exposed to  Frankliniella occidentalis  or  Myzus persicae  were similar to those without insects. However, on plants infested with  F. occidentalis , areas of the infested leaf with feeding damage sustained higher  S. enterica  populations than areas without damage. The spatial distribution of  S. enterica  cells on leaves infested with  F. occidentalis  may be altered resulting in higher populations in feeding lesions or survival may be different across a leaf dependent on local damage. Results suggest the possibility of some specificity with select insects and the persistence of  S. enterica . Additionally, we demonstrated the potential for phytophagous insects to become contaminated with  S. enterica  from contaminated plant material.  S. enterica  was detected in approximately 50% of all  M. quadrilineatus ,  F. occidentalis , and  M. persicae  after 24 h exposure to contaminated leaves. Particularly, 17% of  F. occidentalis , the smallest of the insects tested, harbored more than 102 CFU/F . occidentalis . Our results show that phytophagous insects may influence the population dynamics of  S. enterica  in agricultural crops. This study provides evidence of a human bacterial pathogen interacting with phytophagous insect during plant infestation.