Areawide management of the cotton boll weevil: use of a spatio–temporal model in augmentative biological control

Abstract Recent advances in computer technology have facilitated the development of spatio–temporal models for simulation of ecological systems. The explicit modeling of space allows scientists to investigate the effects of spatial arrangements and heterogeneities, as well as temporal changes, in model systems. We describe an example of a host–parasitoid spatio–temporal model, consisting of integrodifference equations, which model both biological processes and population dispersal. Our model ecosystem consists of the host, boll weevil, ( Anthonomus grandis Boheman) (Coleoptera: Curculionidae), and its exotic parasitoid, Catolaccus grandis (Burks) (Hymenoptera: Pteromalidae). We use the model to explore different strategies in the augmentative biological control of the host by simulating different release methods (single or multiple sites, aerial release), and the effects of wind and heterogeneities in host density on efficacy of the parasitoid. Our preliminary simulations indicate greater host suppression when the parasitoid is released over multiple sites, or aerially, despite identical release rates. The methods used to simulate wind effects resulted in plausible dispersal and parasitization patterns, but the inclusion of heterogeneities in host densities resulted in perhaps non-intuitive parasitization patterns, likely due to boundary effects. Data are being collected currently for calibration and validation of this model. With further development, this spatial model should be useful in designing optimal strategies for the augmentative release of C. grandis against the boll weevil as part of an areawide integrated pest management program.