E. faecalis Exhibits Virulence Towards S. Carpocapsae

Abstract

Steinernema carpocapsae, a pathogenic nematode, penetrates and kills insects to use them as a source of nutrition and a place for reproduction. S. carpocapsae does this through anally releasing its bacterial symbiont into the hemocoel of its insect host. Its bacterial symbiont, X. nematophila, releases lipases and toxic agents to kill the insect, as well as antibiotic agents that are able to keep any competitive bacteria from colonizing the insect cadaver. One competitive bacterium, E. faecalis, is able to resist the antibiotic agents secreted by X. nematophila, allowing E. faecalis to colonize the insect cadaver. This study investigated how S. carpocapsae reacts when exposed to E. faecalis, and whether or not E. faecalis is virulent towards S. carpocapsae. This study also investigated what role X. nematophila plays in resisting this possible virulence. Symbiotic and aposymbiotic nematodes were exposed to E. faecalis, and their survival rates were observed. Survival curves showed that S. carpocapsae was susceptible to E. faecalis during exposure. Survival assays showed inconsistencies in the difference in virulence of E. faecalis towards S. carpocapsae with and without X. nematophila was present. The results suggest that E. faecalis is virulent towards S. carpocapsae, and suggest that more work is needed to observe how X. nematophila affects the virulence E. faecalis shows towards S. carpocapsae.