MODELING SELECTION FOR RESISTANCE TO METHODS OF INSECT PEST-CONTROL IN COMBINATION

The development of resistance to insecticides is now widespread among insects. Other methods of pest control are also potentially at risk of encountering resistance. A modelling approach is presented here to ev aluate the effects of combining methods of insect pest control on the selection for resistance to the control methods. This analysis is base d on partitioning the total mortality acting on a population into its constituent components from all known sources, and these are related t o selection for resistance. When two control methods are used in combi nation, selection for resistance against the two is a linear function if the two don't interact, otherwise it may be sublinear or supralinea r. A specific example is presented using a model of the Olive fruit fl y (Dacus oleae Gmel.) and employing food-baited and pheromone-baited t raps for control. The control methods that appear least likely to enco unter resistance are natural enemies and the use of pheromone traps fo r male annihilation. These should be integrated into a control program where possible to minimize the development of resistance to other con trol methods being used.