Collembola diet-switching in the presence of maize roots vary with species

Collembola are known to feed on a wide range of soil material, predominantly rhizosphere fungi, and root-derived substances. However, diet switching from these usual food sources to living roots (herbivory) was previously demonstrated for one species of collembola, Protaphorura fimata, a euedaphic species. The objective of this study was to determine if diet switching can be applied to another collembola species, Folsomia candida Willem. This hemiedaphic species was given different combinations of maize plants (-13.28% δ13C, 3% δ15N) and 15N-enriched rye grass litter (-28.88% δ13C, 17 516.86% δ15N) in a C3 soil system (-27.27% δ13C, 5.27% δ15N) under controlled conditions. After 8 wk, there was clear evidence of root feeding because the δ13C signature in collembola tissue was -19.28% in the presence of maize plants alone and -18.29% with maize plants grown in soil mixed with ryegrass litter, whereas collembola in unplanted soil microcosms had a δ13C signature of -23.66%. Data analysis with a two-source isotope mixing model indicates that up to 60% of the carbon requirements of F. candida were derived from living maize roots. Whether collembola root feeding is due to grazing on roots directly or on mycorrhiza (root-fungus association) requires further investigation.