Alimentary Studies of Seven Common Soil-inhabiting Collembola of Southern Sweden

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AbstractThe gut contents, amount and several ingredients, have been studied in seven of the commonest soil-living collembola in Southern Sweden. Between 20.6 and 5I.5 per cent of all observed specimens of the different species have no gut contents at all. The possibility that the gut contents are not visible in the lactic acid mounts is discussed. Another possibility is that the gut was emptied in connection with moults. The distribution of the gut contents among the different body segments was studied. With the help of these studies it was possible to obtain an approximate expression for how great a part of all the guts of the population is filled. The percentage of individuals with filled guts varies between 3I.3 and 52.5. It may be concluded from these studies that some species (e.g. Folsomia quadrioculata) eat more sporadically than others (e.g. Isotoma notabilis). It was also concluded that deep-living species more often have filled guts than those that live nearer the surface. This is very probably due to their food being qualitatively inferior to the food of the others. Greater quantities must therefore be treated in the guts of the deeper-living species. This must be of certain significance to the soilbiological importance of the different species. The following ingredients of the gut contents were studied in some detail: (I) Occurrence and quantity of fungal hyphae. (2) Spores. (3) Pollen grains. (4) Exuvia of collembola. (5) Mineral particles. (6) Amorphous mass. Fungal hyphae do not seem to be so common an ingredient of the food of the collembola species which have been examined as the statements of the literature seem to indicate. A considerable proportion of the animals with gut contents, between I2.6 and 7I.I per cent, have no fungal hyphae at all in their guts. It appears as if the amount of fungal hyphae eaten varies with the depth at which the diffefent species tend to live, and inversely with the amount of ingested food. The more superficially the species lives, the less food the individuals eat and the greater the fungal part of the eaten food is. This indicates, in my opinion, that fungal hyphae are the most valuable ingredient of the food of these species. Spores, pollen grains and exuvia are of minor importance. Mineral particles are common ingredients in the gut and this indicates that these species contribute in considerable degree to the transport of minerals in the soil. Amorphous mass, consisting for the most part of unidentifiable material, is almost always a conspicuous ingredient of the gut contents.