Effects of food quality on growth and body composition of the collembolan Orchesella cincta

The effects of food quality on growth and body composition of the collembolan Orchesella cincta (L.) (Entomobryidae) were investigated to determine optimal values for dietary nitrogen, Hyphae of Cladosporium cladosporioides containing 2.2%, 2.7%, 4.0% and 6.2% nitrogen were used as food sources. These different nitrogen contents were obtained by adjusting the medium on which the fungi were grown. Collembola were fed on one of these four food sources for 8 weeks. O. cincta grew faster and reached a higher asymptotic body mass when fed on fungi with 4% or 6.2% nitrogen content: this effect decreased with higher nitrogen content. The lipid concentration in the animals was negatively correlated with dietary nitrogen content, whereas protein concentration was positively correlated. Glycogen concentration was not found to correlate with the composition of the food. A mechanism is proposed by which O. cincta compensates for low dietary nitrogen by consuming more to maintain a relatively constant amount of protein in its body and, as a result, accumulates more fat than animals fed on fungi with a higher nitrogen content.