Influence of nematode age and culture conditions on morphological and physiological parameters in the bacterial vesicle of Steinernema carpocapsae (Nematoda: Steinernematidae)

Yolanda Flores-Lara, Darby Renneckar, Steven Forst, Heidi Goodrich-Blair, Patricia Stock

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


Steinernema spp. third-stage infective juveniles (IJs) play a key role in the symbiotic partnership between these entomopathogenic nematodes and Xenorhabdus bacteria. Recent studies suggest that Steinernema carpocapsae IJs contribute to the nutrition and growth of their symbionts in the colonization site (vesicle) [Martens, E.C. and Goodrich-Blair, H., 2005. The S. carpocapsae intestinal vesicle contains a sub-cellular structure with which Xenorhabdus nematophila associates during colonization initiation. Cellular Microbiol. 7, 1723-1735.]. However, the morphological and physiological interactions between Xenorhabdus symbionts and Steinernema IJs are not understood in depth. This study was undertaken to assess the influence of culture conditions and IJ age on the structure, nutrition, and symbiont load (colonization level) of S. carpocapsae vesicles. Our observations indicate the vesicles of axenic IJs are shorter and wider than those of colonized IJs. Moreover, as colonized IJs age the vesicle becomes shorter and narrower and bacterial load declines. The colonization proficiency of several bacterial metabolic mutants was compared between two cultivation conditions: in vitro on lipid agar and in vivo in Galleria mellonella insects. Colonization defects were generally less severe in IJs cultivated in vivo versus those cultivated in vitro. However, IJs from both cultivation conditions exhibited similar declining bacterial load over time. These results suggest that although the vesicle forms in the absence of bacteria, the presence of symbionts within the vesicle may influence its fine structure. Moreover, these studies provide further evidence in support of the concept that the conditions under which steinernematid nematodes are cultivated and stored affect the nutritive content of the vesicle and the bacterial load, and therefore have an impact on the quality of the nematodes for their application as biological control agents.

Original languageEnglish (US)
Pages (from-to)110-118
Number of pages9
JournalJournal of Invertebrate Pathology
Issue number2
StatePublished - Jun 2007


  • Bacterial vesicle
  • Culture conditions
  • Metabolism
  • Nematode age
  • Steinernema carpocapsae
  • Xenorhabdus nematophila

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics


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