Mucilaginous seeds and algal diets attract soil Collembola in preference tests

• Soil-dwelling Collembola differ in their preference behaviour.
• One species preferred mucilaginous seeds to soil fungi.
• Collembola are able to distinguish different species of algae.

Collembola are abundant in soils and with primary producers interact directly (by grazing algae, seeds, seedlings or roots) or indirectly (by altering the composition of soil microbial communities). Direct collembolan herbivory influences the establishment of seedlings and the dynamics of plant populations whereas grazing on algae affects their biomass, community composition and dispersal. Studies on feeding behaviour of Collembola have mainly focused on fungi, whereas primary producers as resources have seldom been studied. We assessed the feeding preference of two Collembola species (Folsomia candida and Folsomia fimetaria) for food sources from different functional groups using dual choice olfactometers. A preferred fungal species (Alternaria alternata) was compared with two terrestrial microalgae (Chloroidium angusto-ellipsoideum and Pabia signiensis) as well as mucilaginous seeds (Plantago major). A second experiment investigated the choice behaviour of F. candida between different species of common green algae in soils (Chlorella vulgaris, Stichococcus mirabilis, Stichococcus bacillaris and Coccomyxa sp.). Generally, feeding preferences stabilised over 48 h. F. candida avoided P. signiensis compared to the other three food sources whereas F. fimetaria preferred the seeds of P. major to the alternative diets. When only soil algae were offered, F. candida was able to distinguish between different species: S. mirabilis was clearly preferred to S. bacillaris and C. vulgaris. Our results reflect that both Collembola may use a wide range of resources if available and differ in their preference behaviour. Selective feeding on algae or mucilaginous seeds has the potential to modify soil microorganism communities, soil properties and the establishment of seedlings.