ReviewFood preferences of enchytraeids

- Several feeding strategies exist within the family Enchytraeidae.
- Depending on the species, enchytraeids can be classified as primary decomposers or secondary decomposers/sapro-microphytophages.
- They are not plant parasites, but have often been wrongly accused of damaging higher plants.
- They have little or no cellulolytic capability.
- Further research on the feeding ecology of individual enchytraeid species is still required.

The aim of this review is to evaluate the food sources for enchytraeids and to contribute to the current knowledge of their feeding preferences. Several food sources have been described in detail: (1) plant material, (2) macroalgae, (3) animal remains, (4) feces of invertebrates, (5) bacteria, (6) fungi, (7) microalgae, (8) nematodes, and (9) locust eggs. The present article considers selective ingestion, digestion, and factors affecting enchytraeid food selection. We also provide basic information on enzymatic activity, particularly cellulolytic capability. Recent findings on Cognettia sphagnetorum, which have shown that several cryptic species were hidden under this single species name, shed new light on the somewhat inconsistent data presented in the literature over a long time. Apart from that, the recurrent issue of enchytraeids as plant pests is re-discussed here. This unsupported assumption is still the subject of general agricultural textbooks and requires further clarification. Contrary to old hypotheses, potworms are not plant parasites, and they have little or no cellulolytic capability. Enchytraeids can be divided into two groups: (1) primary decomposers and (2) secondary decomposers/sapro-microphytophages. There is also some evidence, albeit weak, that some species prey on nematodes. So far, the trophic preferences of only a few enchytraeid species have been studied in detail, but it is evident that several feeding strategies exist within the family. These studies include direct observation of feeding behavior, gut content analyses, enzymatic analyses, cultivation on different nutrient sources, choice tests, various types of soil microcosms, litter bags, and isotopic techniques. Molecular methods have been used only occasionally, although they could largely support further necessary research on potworm feeding ecology.