Studies on populations of Folsomia candida (Insecta: Collembola) : The productivity of populations in relation to food and exploitation.

Experiments are described that were designed to investigate the effects of food availability and rate of exploitation on the growth and production of populations of Folsomia candida (Willem). In an initial experiment in which there was excess food it was found that increasing the rate of exploitation resulted in increases in both the numerical and biomass productivity of the populations. In a second experiment it was shown that, when there is severe competition for food, the rate of exploitation does not affect either the biomass or the numerical production. It is concluded that the effect of overcrowding, in the form of competition for space, does contribute to the growth in numbers of populations, but that the supply of food plays a more important role in regulating the population. Anomalous results, showing that exploitation has a lesser effect when there is severe competition for food, are discussed.