A comparative study of the life strategies of two bacterial-feeding nematodes under laboratory conditions. 3, Influence on the initial nematode density on the interactions of Arobeloides nanus (de Man 1880) Anderson and Dolichorhabditis dolichura (Schnei

Population development and interactions between two bacterial-feeding nematodes Acrobeloides nanus and Dolichorhabditis dolichura were studied in mixed cultures at different initial density of nematodes. Population dynamics of the two studied species differed significantly in both competition experiments, with the initial numerical advantage of A. nanus as well as with the initial numerical advantage of D. dolichura. In all experimental variants population peak of D. dolichura occured always earlier than that of A. nanus. Population dynamics of A. nanus and D. dolichura depended significantly on the initial density of the second species in the mixed cultures. The higher initial density of D. dolichura the less abundant populations of A. nanus were noticed. However, no consistent trend in the influence of the A. nanus initial density on the abundance of D. dolichura was found. Numerical advantage of D. dolichura never led to the extinction of A. nanus and in the opposite, numerical prevalence of A. nanus in two cases resulted in a complete elimination of D. dolichura. Population dynamics of A. nanus and D. dolichura in mixed cultures showed a distinct difference in the way of food utilisation by these two species. As food resources become scarce with time, D. dolichura density decreased but A. nanus density started to increase. It appears therefore that, under the present laboratory conditions, A. nanus was the better competitor. That species maintained a positive growth rate even at low food concentrations at which its competitor could no longer sustained.