[The dependence of fertility on egg density in Drosophila melanogaster]

The authors investigated the influence of larva competition on the dynamics of Drosophila number in non-overlapping generations. The egg number in generation (n + 1) was evaluated in 10 populations different by egg density in generation n (from 10 to 400 eggs for 3 ml of food in 10 ml test tubes). To estimate the fecundity were used fruit flies collected during three days from the beginning of imago appearance. Only those densities that provide the development without time delay because of competition were used (from 10 to 90). The model of number dynamics was constructed on the base of experimental data. The results of the model testing and experimental evidence allow to conclude: 1) If the time of substrate use is limited in non-overlapping generations the dynamic of population number is in the area of complex cycle regime far from equilibrium. Stable regime of number dynamic is possible only after very strong changes in fitness parameters. 2) Survival of Drosophila preimago is dependent on a number of factors involved successively at the different larva densities. 3) In modelling of number dynamics it is necessary to use a combination of functions that describe all factors successively involved in imago appearance while the density is increasing. 4) The general approach is suggested to determine the dependence of fly numbers in (n + 1) generation on numbers in n generation using only understandable biological parameters.