ABSTRACT
202This chapter begins with a consideration of simple population models. The sterility formulation proposed by Knipling is then included in the population models, and these are elaborated in systematic fashion to include the major biological factors that will affect the success of a sterile insect technique (SIT) control programme. These factors include residual fertility, differential competitive ability of wild and sterilized males, mating patterns, immigration, and various combinations of these features. Also examined are density-dependence, age structure, population aggregation, Allee effect, biotic interactions with other species, and then integration of the SIT with other control methods. It was found that combinations of factors are often synergistic: combinations of detrimental factors such as residual fertility and inferior competitive ability put severe limits on the probable success of the control programme, while combinations of control methods are much more likely to succeed than single control methods. This is because each control method needs only to account for a smaller proportion of the total mortality when combined with other methods than when acting alone. The barrier width is computed to protect an area from pests outside the controlled area using a diffusion equation, and a case study is presented using Mediterranean fruit flies. The redistribution of sterile males released from aircraft travelling along predetermined flight lines is also addressed using a diffusion equation. To minimize costs, a short method is presented to calculate the optimal frequency of releases, distance between flight lines, and number of sterile males released on each flight. This short method is capable of calculation using a hand calculator. Tentative results are also presented on optimizing the number of sprays and time intervals between sprays of a pest population in preparation for an SIT project. The question of whether to release only sterile males or both sexes is examined in the light of results for tephritids. Parameter estimation is mentioned, and also an assessment of the models presented herein. Finally, a brief section on future needs and trends for modelling the SIT is presented.
