Pristionchus
Contents
Rev: 08/29/2008
Pristionchus |
Contents |
Rev: 08/29/2008 |
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Classification |
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Hosts | |
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Morphology and Anatomy |
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Life Cycle |
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Economic Importance |
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Damage |
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Distribution |
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Management |
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Feeding |
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References |
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Synonyms:
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Older female with eggs hatching in uteri
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Females:
Diovarial, amphidelphic |
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| Males: Showing testis, spicules and gubernaculum | |
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Pristionchus spp. have cellulases, presumably through horizontal transfer from microbes (Smant, 1998).
Unlike the rhabditids, Pristionchus and other diplogasterids do not have a grinder in the basal bulb of the esophagus, so there are living bacteria in the intestine.
The mouth also differs from the tubular stoma of the rhabditids and has two forms, with teeth (eurystomatous) or without teeth (stenostomatous). Tooth formation is triggered by starvation, similar to the dauer trigger in C. elegans.
Pristionchus can feed on different food sources. Stenatostomous worms can feed on bacteria while eurystomatous PristionchusPredation on other nematodes:
Pristionchus sp. with remains of prey.
Dauerlarva formation occurs under conditions of high nematode density and low food availability, similar to C. elegans.
The genus Pristionchus is closely associated with scarab beetles – 23 species have the association with various species of beetles. Sommer et al (2008) separate species based on one nucleotide difference. Mating occurs if difference is < 1 nucleotide, fails if > 1 nucleotide.
The nematode–insect association, in which nematodes infest the surface of insects and wait for their hosts to die before resuming development on the cadaver, is known as necromeny (Hong et al, 2008). Pristionchus nematodes infest live insects but do not noticeably reduce the fitness of their hosts; but consume the microorganisms on the decomposing carcass after death of the insect.
Developmental phenomena such as formation of dauer larvae formation, and different forms of the mouth can be influenced by changes in temperature and food availability to the host insect. (Hong et al., 2008).
The dauerlarva invades the insect, waits for insect death and then feeds on decomposing microbes – a necromeny association. Necromeny may be a pre-adaptation in the evolution of parasitism.
Each nematode species is able to detect its corresponding beetle by olfactory signals and the nematodes are attracted to the sex pheromones of the beetles.
