Pathogens in natural C. elegans and C. briggsae populations. (A) Fungal pathogens. Top three panels: The nematophagous fungus Harposporium sp. JUf27 was isolated from this dead C. elegans individual O143.12 (29 October 2008). JUf27 can infect the intestine of C. elegans N2 and produce hyphae that invade the whole body, resulting in death within six to eight days (middle panel). New spores are then produced at the surface of the dead nematode (right panel). The host response that it provokes has been characterized transcriptionally . Bottom three panels: Fungal pathogen JUf31 in Orsay apple O641 on C. briggsae, Drechmeria coniosporia. Another D. coniosporia strain JUf28 was isolated from apple O567 on a Pristionchus sp. and deposited as CBS129433 at the CBS Fungal Biodiversity Centre, Utrecht, The Netherlands by Nathalie Pujol. These spores also develop into hyphae that invade the nematode body (middle panel) and produce a new generation of spores at the surface of the dead nematode (right panel). (B) Microsporidial infection in C. elegans in Orsay apple O695. Two infected dauer juveniles, in the microsporidial groove stage (left) and in the spore stage (right) (see  for microsporidial stages). Both groove and spore stages were also seen in C. elegans L2 larvae in apple O575. (C) Bacterial pathogen Elizabethkingia sp. (strain JUb129), found on C. elegans in Orsay apple O675, here shown on C. elegans N2. The bacteria induce worm bagging and then dissolve their cuticle. On the right, a larva is seen within her mother's corpse. Bars: 10 μm, except otherwise indicated.