Leslie model for predatory gall-midge population

A Leslie matrix model for predatory gall-midge is constructed. From the model we estimate the stable age distribution which is important when the gall-midge is used in biological control. We compare the two common parametrizations of Leslie matrix., i.e. the flow-birth and the pulse-birth projections. We show that both parametrizations lead for the given data set to practically the same results. Then we study the optimal gall-midge introduction scheme which leads quicker to the stable age distribution if only certain instars can effectively be introduced. This is also important, because in biological control we need to minimize the time that a population needs to reach the stable age distribution. © 2000 Elsevier Science B.V. All rights reserved.