Selection pressure is one of the factors required for a population to evolve. So what exactly is selection pressure? Anytime an environmental factor is changed so that it impacts the reproductive success of some individuals in a population more than others, there is selection pressure. (See Evolution and The Kochia and Dicamba Story for more information on selection pressure.) For example, if a farmer treats a cornfield with a rate of soil insecticide that is lethal to some population members but not to others, they are applying selection pressure. The survivors pass on their genes more often and the population will evolve.
The data collected by Dr. Meinke, including ecological information such as data about CRW behavior and fitness (or overall health), can be used to help determine the level of selection pressure. Data about CRW response to a specific technology or environmental factor can be used in computer simulation models to address questions about population changes and the potential for resistance to develop. Field-collected data on the timing of adult emergence for example, could be used in the model to predict the importance of random mating between insects in a population.