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Schlagwörter:
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Zusammenfassung:
The nematode Pristionchus pacificus is a genetic and evolutionary model to elucidate the ubiquitous insect- nematode-bacteria complex. P. pacificus has a facultative affiliation with scarab beetles and relies on the bacteria that decompose the beetle carcasses as a food source. Though, when population densities increase, resources can become scarce; P. pacificus can respond by inducing either the dauer stage or the predatory mouth form, the latter allowing for feeding on other nematodes. However, given that scarab beetles spend most of their lives (as eggs, grubs, and pupae) below ground, little is known about the dynamics and succession of the beetle-nematode- microbe interaction. We initiated field studies to understand the succession of the nematode in association with its microbiome in the beetle ecosystem. The dynastid beetle Oryctes borbonicus from La Réunion Island serves as an exceptional model system due to its nematode infestation rate of more than 90% at one location, which provides ample material for experimental manipulation. Specifically, we caught and killed beetles, placed their carcasses back in the soil, and analyzed the decaying beetle over 12 weeks in two-week intervals. We found that the worm exhibits a boom and bust strategy on the carcass with an unexpected dynamic pattern that is not induced by specific bacterial species, though the presence of the nematode influenced the bacterial composition on the beetle carcass. Additionally, the microbiome of the nematode derives largely from the decaying beetle and not from the surrounding soil. We will present our current understanding of the Pristionchus-beetle association and will also describe our recent analysis of the nematode association with beetle grubs in the soil. These studies help towards a comprehensive understanding of the true ecology of a nematode model system.
