In this study, we explore how the functional response framework can be applied to human-pest management. Here, managers take the role of predators foraging on pests and facing monetary costs for survey and control. To investigate this framework quantitatively, we simulated the management process using a spatially-explicit individual-based model and spatially-implicit Monte-Carlo simulations. We confirmed some of the results analytically by deriving equations for the number of pest managed from first principles. We explored various scenarios so as to capture different functional response behaviours. Each scenario has two elements: 1) a pest spatial pattern in a 2-dimensional domain which can be random, clustered or regular, and 2) a management strategy which can be random or adapted from the adaptive cluster sampling strategy (Thompson, 1990). By graphing the number of pests controlled versus pest density, we obtained management functional response curves.
Results/Conclusions
Whether the management functional response was shaped like a type I, type II or type III functional response depended on the management costs and the search area. We obtained a type I by setting the survey cost to be greater than 0 and the removal cost to 0. We obtained a type II by setting both costs to be greater than 0. To obtain a type III, we reduced the search area at low densities by setting a maximum number of empty cells surveyed in a row before stopping management. We thereby simulate a manager estimating that the probability of encountering a pest is too low to be worth the search effort at a low pest density. However, the management strategy and the pest spatial distribution had very little effect on the functional response. We applied our model to the management of mountain pine beetle epidemic in Cypress Hills, Saskatchewan, Canada. Our simulations matched the real number of attacked trees controlled by managers and showed a type II functional response. We showed how to make an analogy between functional responses in predator-prey interactions and in human-pest management and thereby, apply insights from the functional response framework to pest management.