JOINT EFFECTS OF RELEASE OF STERILE MALES AND IMMIGRATION OF FERTILIZED FEMALES ON A DENSITY REGULATED POPULATION

The joint effects are studied of the release of sterilized males and immigration of mated females on a population whose discrete generation recursion is, N′ = N( RK K + (R - 1)N) where, R ≡ reproductive potential, K ≡ equilibrium. This form of growth is derived from life history considerations so that the impact of the release of sterile males on immatures and on adults can be compared. When the migration parameter and the sterile male release parameter are small, the system has three internal equilibriums (the middle one being unstable). Increase in immigration or in release results in one stable equilibrium. The practical conclusion is that migration must be very small in order for the release of sterile males to be effective on suppressing numbers of adults, while more migration can be tolerated if, as in many agricultural pests, immature stages are the object of concern. © 1978.